Brassica oleracea, Capitata Group
Brassicaceae
Cabbage thrives in cool weather. In most areas, you can plant an early crop for fresh eating and a late crop—usually the more problem-free and tasty of the two—for use into the winter months. Choose early varieties such as ‘Primax’ for summer harvest; midseason and late-season cultivars for storage. Mini cabbages such as ‘Gonzales’, harvested when only 6 inches in diameter, are perfect for small gardens. Loose-leaf versions include Chinese cabbages, like bok choy (see the Asian Vegetables entry), and ornamental cabbages.
Planting: You can buy transplants from a local grower, but cabbage is easy to grow from seed. Plan to set out early types 4 weeks before the last expected frost date. Sow seeds indoors, ¼ inch deep and 2 inches apart, around mid-January or February in the South and in March in the North. Place in a sunny spot or under lights with temperatures between 60° and 70°F, and keep the soil uniformly moist. When daytime temperatures reach 50°F and seedlings have three leaves, plant them outdoors.
Plant seedlings in the garden slightly deeper than they grew in flats. Space 6 to 12 inches apart in rows 1 to 2 feet apart. Wide spacing produces bigger heads, but young, small cabbages are tastier. To get both, plant 6 inches apart and harvest every other one before maturity. Stagger plantings at 2-week intervals for a longer harvest.
Start your late crop in midsummer, sowing seeds in flats or directly in the garden. Space these seedlings farther apart than the spring crop, and place them so a tall crop, such as corn or pole beans, provides some afternoon shade.
Growing guidelines: Soil texture is not critical, but early cabbages do best in a sandy loam, while later types prefer a heavier, moisture-retaining soil. Side-dress seedlings with rich compost 3 weeks after planting. Hand-pull weeds to avoid damaging cabbage’s shallow roots; mulch to keep the soil moist. Uneven watering can cause a sudden growth spurt that will make the developing head split. If you see a cabbage head starting to crack, twist the plant a half turn and pull up to slightly dislodge the roots and thus slow the plant’s growth. Or use a spade to cut the roots in one or two places 6 inches below the stem. This also helps to prevent cabbage from bolting (producing a flowerstalk).
Avoid wetting the foliage during cool weather or periods of high humidity, because constantly wet leaves are prone to disease. Cut back on water as cabbage matures. If leaves start to yellow, provide a midseason nitrogen boost with compost tea. See the Compost entry for instructions for making compost tea. This type of feeding can also encourage a slow-growing crop to mature before hot weather or a winter freeze sets in.
Problems: Major cabbage pests include cabbage maggots, imported cabbageworms, cabbage loopers, and cutworms. You’ll find information on controlling them in The Top 10 Garden Insect Peststable. The harlequin bug, a small shiny black insect with red markings, causes black spots and wilting leaves; control by handpicking or applying insecticidal soap. Slugs may chew ragged holes in leaves; see the Slugs and Snails entry for controls.
Black leg, a fungal disease, forms dark spots on leaves and stems. Black rot symptoms include black and foul-smelling veins. Clubroot prevents water and nutrient absorption. Fusarium wilt, also known as yellows, produces yellow leaves and stunted heads. Remove and destroy plants affected by these diseases. If clubroot has been a problem in your garden, test soil pH before planting and add ground limestone if needed to raise the pH to at least 6.8
Good growing conditions, crop rotation, and the use of disease-resistant cultivars are the best defenses against cabbage-family crop problems. Also, thoroughly clean up the garden at the end of the season, removing all remaining leaves and roots.
Harvesting: Use a sharp knife to cut heads when they are firm. Leave stalks and roots in place to produce tasty little cabbages; eat them like Brussels sprouts or let them develop into a second crop of small heads. Fresh cabbage has the best flavor, but late-season cultivars keep well in a moist, cool place (32° to 40°F) for as long as 5 to 6 months. Use split heads for making sauerkraut.
Caladium. Summer or fall tuberous plants grown for foliage.
Description: Selections of Caladium bicolor, angel wings or fancy-leaved caladium, light up shady areas with their 6- to 12-inch pointed, heart-shaped leaves marked with white, pink, red, and green. Leaves are borne in 1- to 2-foot, loose, arching bunches. Hooded, off-white flowers are inconspicuous. Hardy only in frost-free soil; treat as annuals or container plants elsewhere. Zone 10.
How to grow: Start caladiums indoors about 4 to 6 weeks before all danger of frost is past. Plant tubers in a loose, fast-draining mix such as peat, sand, perlite, vermiculite, and compost, barely covering the tops. (The end with tiny buds is the top.) Plant the tubers in shallow boxes, flats, or pots. Keep warm (70°F is ideal), and give plenty of water once growth begins. Plant out after the soil is warm, in partial shade with a few hours of morning sun, or under tall trees. Caladiums grow best in fertile, well-drained, moist, humus-rich soil. Apply fish emulsion or compost tea every 3 to 4 weeks to encourage new leaves and bright colors. See the Compost entry for instructions for making compost tea. Handpick or trap slugs and snails. Unless you live in Zone 10 or warmer, dig up caladiums after the first frost, remove the soil after it has dried, and store the tubers almost dry at around 65°F in peat or vermiculite. Start them again in spring.
Landscape uses: Mass caladiums in shady beds and corners, or tuck groups of three to five as accents between larger plants such as ferns, hostas, or shrubs. To brighten shady areas, use cultivars with white-variegated leaves. Show off several caladiums in a large container with elephant’s ears (Colocasia spp.), begonias or impatiens, and trailing petunias in complementary colors.
Pot marigold. Spring- and fall-flowering annuals; edible flowers; herbs.
Description: Calendula officinalis, pot marigolds, bear single or double, daisylike, 2- to 4-inch flowers in shades of yellow, gold, and orange on 1- to 2-foot-tall open mounds of rough, straplike leaves.
How to grow: Start indoors in late winter or plant seeds directly where they are to bloom. Lightly cover the seeds in a sunny area in well-drained, average soil as soon as frost leaves the ground. Transplant or thin to stand no more than 1 foot apart. Pot marigolds will also self-sow.
Landscape uses: Mass calendulas in mixed annual and perennial plantings or in a cutting garden, or use them to add bright splashes of color to an herb garden. You can also use them to conceal the dying foliage of spring bulbs.
Calibrachoa, million bells, trailing petunia. Summer-blooming annual or tender perennial.
Description: Closely related to petunias, calibrachoas are 3- to 9-inch-tall plants with trailing stems and a mounding habit. Abundant 1-inch-wide, trumpet-shaped flowers appear continuously from early summer to frost. Blooms come in shades of blue, purple, red, pink, yellow, gold, and white.
How to grow: Give calibrachoas a site in full sun or very light shade with rich, moist, well-drained soil. Plants tolerate dry spells and continue blooming even in hot weather. They produce very little seed, and available cultivars are vegetatively propagated. Start with purchased transplants and set them outside after the last spring frost. Space plants 8 to 10 inches apart.
Landscape uses: Calibrachoas are ideal choices for containers and hanging baskets. They also make an attractive temporary groundcover or edging for the front of a flowerbed.
Bellflower, harebell. Late-spring- and summer-blooming perennials or biennials.
Description: All bellflowers produce lovely single blue, purple, or white star- or bell-shaped flowers above deep green, often toothed foliage. There are many species and cultivars to choose from. All are usually longer lived in cooler areas. The following are among the best.
Campanula carpatica, Carpathian harebell or tussock bellflower, bears a profusion of upward-facing, open, 1-inch bells in white and blue shades. These blooms are held individually on threadlike stems, usually 8 inches above tight mounds of shiny green 2-inch leaves; flowers appear in early summer and sporadically throughout the growing season. Zones 3–8.
C. glomerata, clustered bellflower, has dense 4-inch clusters of narrow, pointed purple bells on 1- to 2½-foot erect stems above spreading masses of dark green, rough, fuzzy leaves in late spring and early summer. Zones 3–8.
C. persicifolia, peach-leaved bellflower, carries open, 1½-inch, widely spaced white or blue bells on upright stalks to 3 feet above a rosette of slender, 8-inch glossy leaves during summer. Zones 3–7.
C. medium, Canterbury bells, is a biennial usually grown as a hardy annual. It bears loose spikes of showy, 2-inch-long, violet-blue bells on plants 2 to 4 feet tall. Zones 3–8.
How to grow: Plant or divide bellflowers in spring in sunny, average, well-drained soil. Carpathian harebell, especially, needs good drainage. Provide some afternoon shade in warmer zones. Clustered bellflower tolerates wetter sites but not boggy conditions. Remove flowers soon after bloom to encourage rebloom on Carpathian harebell and peach-leaved bellflower. Most come relatively true to type from self-sown seed. Handpick or trap slugs and snails.
Landscape uses: Mass taller bellflowers in borders, cottage gardens, and naturalized areas. The cool blue and white shades of peach-leaved bellflowers contrast nicely with pink and red old-fashioned roses. Carpathian harebells look better in small-scale settings, such as rock gardens, walls, and among cracks in paving stones. Avoid C. rapunculoides, the creeping or rover bellflower, an invasive plant that is almost impossible to control once it gains a foothold.
Though tall bellflowers are striking, the shorter species can be stunning in the front of a border, in rock gardens, and as groundcovers. Try earleaf, or fairy thimble, bellflower (Campanula cochlearifolia), Dalmatian bellflower (C. portenschlagiana), Serbian bellflower (C. poscharskyana), and bluebell bellflower (C. rotundifolia). These species range from 4 inches to 12 inches tall, with graceful bell- or star-shaped flowers in sky blue, blue-violet, lilac blue, purple, or white.
See Iberis
Canna. Summer- and fall-blooming tender perennials.
Description: Canna × generalis, hybrid cannas, bear 4- to 6-inch irregularly shaped blooms in cream, yellow, pink, red, orange, and combinations. The flower clusters appear above substantial clumps of broad green, cream- or yellow-striped, or rich purple-bronze leaves on upright plants 2 to 8 feet tall. Dig and store rhizomes indoors to over-winter in the North; leave in the ground in Zones 7–10.
How to grow: Start cannas about a month before all danger of frost is past. Plant the rhizomes horizontally with the tips pointing up; cover with about 1 inch of potting mix. When the weather warms, plant out in full sun and fertile, well-drained, moist, humus-rich soil. Mulch with compost, shredded bark, or pine needles when the shoots are about 1 foot tall to control weeds and conserve moisture. Give cannas plenty of water during hot weather and drench liberally with fish emulsion or compost tea during the first 6 to 8 weeks. See the Compost entry for instructions for making compost tea. Handpick Japanese beetles. Remove spent flowers if you can reach them. To overwinter cannas in Zone 6 and colder, dig the clumps after frost blackens the foliage and cut them back to 6-inch stubs. Allow the soil to dry, shake it off, and store the clumps in barely moist peat at 46° to 50°F. In spring, cut the clumps into pieces with one to three eyes (buds) each and start again.
Landscape uses: Cannas add a tropical touch—as well as much-needed height—to any flower border. Grow groups of three plants in a border, repeated along its length, or use as accent plants in clusters of three at intervals along a fence or on each side of a gate or driveway. Cannas look great in or along the edge of water gardens, and they’re spectacular container plants, as long as you give them a large container with humus-rich potting soil and plenty of room to spread. For containers, choose cannas with striking foliage, like the yellow-and-green striped ‘Striata’ (also sold as ‘Bengal Tiger’ and ‘Pretoria’) and the red-, orange-, and purple-striped ‘Phasion’ (sold as Tropicanna). Pair them with trailing plants like nasturtiums, gold moneywort (Lysimachia nummularia ‘Aurea’), and ornamental sweet potato vines (Ipomoea batatas ‘Blackie’ or ‘Margarita’). Dark-leaved canna cultivars like ‘Australia’ contrast boldly with red, gold, and orange flowers, and all the tall cannas can temporarily screen out an unsightly view.
One proposal for counteracting the rise of atmospheric CO2 is to plant trees as “carbon sinks.” After all, carbon compounds are a major component of plant cells, so trees represent a huge potential reservoir of stored carbon.
Researchers have discovered other plants that work well as carbon sinks, too, such as switch-grass (Panicum virgatum) and other warm-season grasses. These grasses store carbon in their stems and leaves, but the real carbon sink they stimulate is belowground. The roots of these grasses associate with mycorrhizal fungi that produce a substance called glomalin—a gluey material that contains lots of carbon. Up to one-third of the carbon in soil is stored in glomalin, which helps bind soil particles together and is the key substance that gives soils good tilth. When organic matter content of the soil is high, glomalin tends to be high, too—so simply by following good organic soil management practices in your garden, you’re taking one small step to help fight global climate change.
If you’d like to go beyond that, and you have enough space, consider planting an area of your yard as a carbon sink. Of course, your carbon sink can serve other roles as well. A strategically placed, long-lived shade tree will be a carbon sink that also helps shade your home in the summer. Or a row of evergreens can serve as a windbreak.
If you don’t have the right spot for a majestic shade tree, a stand of bamboo can serve as a carbon sink instead. Bamboo is even more efficient at storing carbon than shade trees are, and bamboo can serve as a living “wall” or screen for a garden room. New varieties have colorful canes that provide a great four-season landscape accent. You can even grow types that produce canes sturdy enough to serve as garden stakes. For most gardeners, the key point in success with bamboo is to choose a clumping type rather than a running type that can easily overrun a home landscape. See the Bamboo entry for details on growing bamboo.
Daucus carota var. sativus
Apiaceae
Orange carrots may be best known, but these sweet, crunchy roots also come in white, yellow, crimson, and even purple. You can grow a rainbow of carrots and taste-test to see which hues are your favorites. More important than color, though, is choosing the right root size and shape to suit your soil. Carrot size and shape varies by type, and there are five major categories. Ball-type, Chantenay, and Danvers carrots have blocky shapes that can produce roots in heavy or shallow soil, while slender Nantes and Imperator carrots need deep, loose soil. All types are available in early and late cultivars; many are disease and crack resistant. Some catalogs don’t describe carrots by type but will point out which cultivars do better in heavy or poor soil.
Planting: To produce the best crop possible, deeply cultivate your planting area or build up a raised bed. Loose, rock-free soil is the goal for optimal carrot root development. If you have heavy soil, add plenty of mature compost.
Start sowing this cool-weather crop 3 weeks before the last expected frost; plant again every 2 to 3 weeks after that. Most cultivars take 70 to 80 days to mature, so sow your last planting 2 to 3 months before the first expected fall frost. In Zone 8 and warmer, plant carrots in fall or winter.
Rake the soil free of lumps and stones. Broadcast the tiny seeds, or for easier weeding, plant in rows. Put a pinch of about six seeds to the inch. They will take 1 to 3 weeks to sprout (they germinate more slowly in cold soil than in warm), so mix in a few quick-growing radish seeds to mark the rows. Cover with ¼ to ½ inch of screened compost, potting mix, or sand—a little more in warm, dry areas—to make it easier for the delicate seedlings to emerge. Water gently to avoid washing seeds away; keep the soil continuously moist for best germination.
Growing guidelines: Thin seedlings to 1 inch apart when the tops are 2 inches high, and be thorough, because crowded carrots will produce crooked roots. Thin again 2 weeks later to 3 to 4 inches apart.
As the seedlings develop, gradually apply mulch to maintain an even moisture level and reduce weed problems. It’s best never to let young carrot plants dry out. However, if the soil dries out completely between waterings, gradually remoisten the bed over a period of days; a sudden drenching may cause the roots to split. Carrots’ feeder roots are easily damaged, so hand-pull any weeds that push through the mulch, or cut them off just below the soil surface. Cover carrot crowns, which push up through the soil as they mature, with mulch or soil to prevent them from becoming green and bitter.
Problems: The biggest threats to carrots are four-footed critters such as deer, gophers, woodchucks, and rabbits. For controls, see the Animal Pests entry. Otherwise, carrots are fairly problem-free.
Keep a vigilant watch—particularly in the Northwest—for carrot rust flies, which look like small green houseflies with yellow heads and red eyes. Their eggs hatch into whitish larvae that burrow into roots. Infested roots turn dark red and the leaves black. Infestations usually occur in early spring, so one solution is to delay planting until early summer, when damage is less likely. Or cover plants with a floating row cover to keep flies away.
Parsleyworms are green caterpillars with black stripes, white or yellow dots, and little orange horns. They feed on carrot foliage, but they are the larval stage of black swallowtail butterflies, so if you spot them on your carrots, try not to kill them. Instead, transfer them to carrot-family weeds such as Queen Anne’s lace, and watch for chrysalises to form, and later, beautiful butterflies!
The larvae of carrot weevils, found from the East Coast to Colorado, tunnel into carrot roots, especially in spring crops. Discourage these grubs by rotating crops.
Nematodes, microscopic wormlike animals, make little knots along roots that result in stunted carrots. Rotate crops and apply plenty of compost, which is rich in predatory microorganisms. (For more controls, see the Plant Diseases and Disorders entry.)
Leaf blight is the most widespread carrot disease. It starts on leaf margins, with white or yellow spots that turn brown and watery. If leaf blight is a problem in your area, plant resistant cultivars.
Hot, humid weather causes a bacterial disease called vegetable soft rot. Prevent it by rotating crops and keeping soil loose. The disease spreads in storage, so don’t store bruised carrots.
Carrot yellows disease causes pale leaves and formation of tufts of hairy roots on the developing carrots. The disease is spread by leafhoppers, so the best way to prevent the problem is by covering new plantings with row covers to block leafhoppers.
Harvesting: Carrots become tastier as they grow. You can start harvesting as soon as the carrots are big enough to eat, or leave them all to mature for a single harvest. Dig your winter storage crop before the first frost on a day when the soil is moist but the air is dry. Since spading forks tend to bruise roots, hand-pull them; loosen the soil with a trowel before you pull. Watering the bed before harvesting softens the soil and makes pulling easier.
Carrots are excellent to eat both fresh and cooked. Note that purple-rooted varieties will lose their purple pigment if cooked in water, but they tend to keep it when roasted.
To save harvested carrots for winter use, prepare them by twisting off the tops and removing excess soil, but don’t wash them. Layer undamaged roots (so they’re not touching) with damp sand or peat in boxes topped with straw. Or store your fall carrot crop right in the garden by mulching the bed with several inches of dry leaves or straw.
See Nepeta
Brassica oleracea, Botrytis Group
Brassicaceae
The sweet and mild flavor of homegrown cauliflower more than justifies the extra care it requires. Cauliflower is not difficult to grow, but it is sensitive to extreme temperatures. Primarily a cool-weather crop, cauliflower won’t produce heads in hot, dry weather and is frost tolerant only as a mature fall crop. Most cultivars need about 2 months of cool weather to mature, though some require as little as 48 days and others more than 95 days. To grow cauliflower successfully, the key steps are to choose the right cultivar for your climate, plant at the proper time, and provide a steady supply of moisture.
Planting: Like other cabbage-family members, cauliflower needs soil that is rich in nitrogen and potassium, with enough organic matter to retain moisture. In warm climates, plant in fall or late winter for an early-spring harvest. In colder areas, cauliflower usually performs best as a fall crop.
To avoid disturbing roots at transplanting, start cauliflower seedlings indoors in peat or paper pots. Plant seeds ¼ to ½ inch deep, 4 to 6 weeks before the last average frost. Provide constant moisture for seedlings but avoid waterlogged soil; use bottom heat, if necessary, to keep the soil temperature around 70°F.
Harden off young plants gradually before transplanting them to the garden. Set the seedlings 15 to 24 inches apart. Make a saucerlike depression around each plant to help hold water. Firm the soil, and water seedlings thoroughly. Cover beds with floating row cover to prevent insect pests from damaging tender transplants.
Growing guidelines: Provide at least 1 inch of water a week, soaking the soil to a depth of 6 inches. Cauliflower requires constant moisture to produce large, tender heads; soil that dries out between waterings will cause heads to open up and become “ricey.” Use a thick layer of compost or organic mulch to conserve soil moisture, limit weeds, and cool the soil. Be careful not to disturb cauliflower roots when weeding, because damaged roots produce uneven growth. Fertilize young plants monthly with fish emulsion or compost tea. If you want to speed up growth, feed every 2 weeks. See the Compost entry for instructions for making compost tea.
When the flower heads (curds) of white-headed cultivars are about the size of an egg, blanch them by shading out the sunlight. Otherwise they’ll turn yellowish and become, if not less tasty, certainly less appealing. Prepare plants for blanching on a sunny afternoon when the plants are totally dry, because damp heads are more susceptible to rot. Just bend some of the plants’ own leaves over the head and tuck them in on the opposite side, or secure the leaves at the top with soft twine, rubber bands, or plastic tape. Use enough leaves to keep out light and moisture, but allow room for air circulation and for the heads to grow.
Once the blanching process begins, be careful to avoid splashing water on the heads or leaves. Unwrap occasionally to check on growth, to look for pests, or to allow heads to dry out after a rain. In hot weather, heads can be ready to harvest in a matter of days. In cool periods, the maturing process can take as long as 2 weeks. Blanching is not necessary when you’re growing varieties that produce purple, lime green, or orange heads, or with self-blanching types, which have leaves that naturally curl over the head.
Problems: Pests—such as aphids and flea beetles—tend to trouble cauliflower more in spring than in fall. Cabbage maggots, sometimes called root maggots, can also be a serious problem. Caterpillars, such as cabbage loopers and imported cabbageworms, are other common cauliflower pests. For more details on these insects and appropriate controls, see The Top 10 Garden Insect Pests.
In boron-deficient soil, cauliflower heads turn brown and leaf tips die back and become distorted. If this occurs, foliar feed with liquid seaweed extract immediately, and repeat every 2 weeks until the symptoms disappear. For subsequent crops, provide boron by adding compost to the soil, or plant fall cover crops of vetch or clover.
Crop rotation, good garden sanitation, and using resistant cultivars will prevent most cauliflower diseases. These include black leg, black rot, clubroot, and fusarium wilt (yellows). See the Cabbage entry for more information on these problems.
If your cauliflower heads taste bitter, chances are the problem was lack of moisture or another factor that slowed the growth of the plants. For your next crop, be sure to plant in soil with plenty of organic matter, keep the soil surface mulched, and water regularly.
Harvesting: Mature cauliflower heads can range in size from 6 inches to 12 inches across. Harvest when the buds are still tight and unopened. With a sharp knife, cut them off just below the head, along with a few whorls of leaves to protect the curds. Use or preserve right away. Note that cooking will cause the color of orange, green, and purple cauliflower florets to fade.
If you don’t have time to harvest your crop before a heavy frost strikes, remember that the heads will still be edible unless they thaw and freeze again. Cut the frozen heads and cook them right away. To store plants for about a month, pull them up by the roots and hang them upside down in a cool place.
A chartreuse relative of both cauliflower and broccoli, romanesco produces heads of bright green, tightly spiraled, pointed florets that typically have a mild, nutty flavor. Also called broccoflower, romanesco has the same cultural needs in the garden as cauliflower and other cabbage family crops.
Apium graveolens var. dulce
Apiaceae
Contrary to popular belief, celery is not all that difficult to grow. The main things this crop requires are rich soil, plenty of water, and protection from hot sun and high temperatures. Grow celery as a winter crop in the South, a summer crop in the far North, and a fall crop in most other areas.
Planting: You can buy transplants from nurseries, but cultivar choices expand when you grow celery from seed. You can choose dark green ‘Tall Utah 52-70R Improved’, experiment with self-blanching types such as ‘Golden Boy’ and ‘Tango’, or try red-stalked varieties such as ‘Redventure’. For a late-summer crop, sow seeds indoors 10 to 12 weeks before the last average spring frost. Soak the tiny seeds overnight to encourage germination. Fill a container with a mix of two-thirds compost and one-third sand, and plant in rows 1 inch apart. Cover the seeds with a sand layer ⅛ inch deep, then cover the flats with damp sphagnum moss or burlap until seeds sprout.
Place in a bright spot out of direct sun, and keep the temperature at 70° to 75°F during the day and about 60°F at night. Provide plenty of water and good drainage and air circulation. Transplant the seedlings into individual pots when they are about 2 inches tall. At 6 inches, harden off the plants for about 10 days, and then transplant them into the garden in a bed that’s high in organic matter (from a cover crop or added compost).
Space the plants 6 to 8 inches apart in rows 2 to 3 feet apart. Set them no deeper than they grew in pots. Water in each seedling with compost tea. See the Compost entry for instructions for making compost tea.
For a fall crop, sow seeds indoors in May or June and follow the same directions, transplanting seedlings in June or July. Provide shade in hot, humid weather.
Growing guidelines: Apply several inches of mulch and provide at least 1 inch of water a week. Gently remove any weeds that might compete for nutrients with celery’s shallow roots. Feed every 10 to 14 days with compost tea or a balanced organic fertilizer. If night temperatures are consistently below 55°F, protect plants by covering them with cloches; otherwise, the stalks become weak.
Blanching celery destroys some nutrients but prevents stalks from becoming bitter. It also protects fall crops against heavy frosts. You can grow a self-blanching variety, such as the heirloom ‘Golden Self-Blanching’, or blanch conventional varieties by one of these methods:
Gradually heap soil up around the plants as they grow, keeping the leaves exposed.
Two weeks before harvest, tie the tops together, and mound soil up to the base of the leaves.
Cover the stalks with large cans (remove both ends first), drain tiles, or sleeves made of paper or other material.
Line up boards, secured with stakes, along each side of a celery row to shut out the sun.
Water carefully after setting up your blanching system, avoiding wetting the leaves and stalks, or they may rot.
Problems: Celery’s main enemies are parsleyworms, carrot rust flies, and nematodes. See the Carrot entry for more information on these pests. Celery leaf tiers are tiny yellow caterpillars marked with one white stripe; control by handpicking. Attacks of tarnished plant bugs show up as black joints or brown, sunken areas; see The Top 10 Garden Insect Pests for controls.
Common diseases include early and late blight, which both begin as small dots on the leaves, and pink rot, which shows up as water-soaked stem spots and white or pink coloration at stalk bases. Crop rotation is the best way to avoid for disease problems.
Distorted leaves and cracked stems can indicate boron-deficient soil; correct by spraying plants with liquid seaweed extract every 2 weeks until symptoms disappear.
Harvesting: Cut the plant off just below the soil line, or cut single stalks of unblanched celery as needed. To preserve a fall crop before freezing temperatures set in, pull up the plants and place them in deep boxes with moist sand or soil around the roots. Store in a cool place; they will keep for several months.
Crested cockscomb, plumed cockscomb, celosia. Summer- and fall-blooming annuals; dried flowers.
Description: Celosia argentea is often subdivided into groups: Cristata, representing the crested cockscombs whose flowers resemble the undulating combs atop roosters’ heads, and Plumosa, which produce feathery plumes of bright flowers. Some sources separate the celosias into two species: C. argentea, the plumed varieties, and C. cristata, the crested ones. However they are identified botanically, celosias bear blooms in a jewel-toned rainbow of cream, yellow, orange, red, and reddish purple. Crested varieties bear wavy, rounded, velvety flower heads that reach 4 to 12 inches across on thick, 6- to 24-inch-tall stems with long, narrow, green or dark red leaves. Feathery plumed cockscombs share the same color range and plant habits, producing 4- to 12-inch-long flamelike heads.
How to grow: Start seeds about 4 weeks before the last frost, or direct-seed outdoors after the ground warms up. Plants resent root disturbance, so transplant carefully into a sunny, well-drained spot with average to fairly rich soil. They tolerate infertile soil and drought very well, but for the largest flower heads, water regularly, side-dress with a high-phosphorus fertilizer such as bone-meal, and stake the taller cultivars. Wide spacing (8 to 12 inches apart for dwarfs, 1½ feet for tall types) produces larger flower heads.
Landscape uses: Dwarf crested cockscombs lend interest to beds, edgings, and pots. Keep tall, large-headed plants in the cutting garden. Plumed cultivars are excellent for massing in beds and borders. For drying, cut either type when in peak color and hang upside down in a warm, well-ventilated place out of direct sun.
Cornflower, bachelor’s buttons. Late-spring- to early-summer-blooming annuals and perennials.
Description: Centaurea cyanus, cornflower or bachelor’s buttons, is a popular summer-blooming annual that bears shaggy, 1½-inch, circular, swollen-based blooms in shades of white, pink, red-violet, blue, and violet. The 1- to 2-foot upright or slightly floppy plants are clad in long, skinny, grayish, fuzzy leaves that become much smaller toward the top.
C. montana, mountain bluet or perennial cornflower, resembles its annual cousin but is a perennial, offering 2- to 2½-inch, open disks of finely cut, fringed petals, almost always in a deep, rich blue, on 1½- to 2-foot open mounds of lance-shaped, gray-green foliage. Zones 3–8.
How to grow: Plant both types in full sun to very light shade in average to less fertile, well-drained soil to keep plants compact.
You can start cornflowers a few weeks ahead of the last hard frost and plant them out as small plants just before the last frost; however, they settle in much better if sown directly after frost leaves the soil in spring or in early fall.
Plant mountain bluets in early spring or early fall. Divide often to keep plants vigorous, or allow the usually abundant self-sown seedlings to replace them. Plants deteriorate soon after bloom, so you may want to cut them back nearly to the ground, leaving a few to produce seeds.
Landscape uses: Grow cornflowers in masses in informal borders, cottage gardens, cutting gardens, or meadow plantings. Site with other plants that can fill the gaps left after bloom. Both naturalize readily; bachelor’s buttons are considered weedy to invasive in some parts of the United States. Cornflower blossoms are edible and make a lovely garnish for salads.
Beta vulgaris, Cicla Group
Amaranthaceae
Grow mild-flavored, prolific Swiss chard for its huge, succulent leaves and celerylike stems (actually leaf petioles). This “leaf beet” prefers consistent cool conditions but withstands cold and heat better than most greens. Varieties vary in stem color, heat and pest tolerance, and flavor. ‘Monstruoso’, an Italian heirloom, and ‘Fordhook Giant’ produce broad white stalks that may stand in for celery or bok choy. The multicolored stems of ‘Bright Lights’ make it a popular choice for container gardening and edible landscaping. Chard selections with gold stems (‘Bright Yellow’) or red ones (‘Rhubarb’) are as ornamental as they are nutritious and tasty. Chard leaves’ flavor is similar to beet greens or spinach.
Planting: Chard tolerates partial shade and a range of soils. In spring, broadcast seeds directly in the garden 1 to 2 weeks before the last expected frost; rake to cover seeds. You can also plant seeds or buy transplants in late summer for a fall crop.
Growing guidelines: Thin seedlings gradually until plants are 8 to 10 inches apart; use the thinnings in salads or sauté them lightly. When plants are about 6 inches tall, fertilize them with alfalfa meal or fish emulsion. Mulch well in areas with hot summers and keep the soil consistently moist. If your plants eventually bolt (produce flowerstalks) during a hot spell, uproot them, and look forward to your fall crop.
Problems: See the Spinach entry for disease and insect control.
Harvesting: Pick leaves as needed. Baby leaves are very tender, larger leaves are best prepared like spinach; cook the stems as you would asparagus.
Prunus spp.
Rosaceae
Do you crave the flavor of sweet cherries despite their steep price? Do you love homemade cherry pie or the sight of a cherry tree in full bloom? If so, grow your own sweet and tart cherries and enjoy a hearty harvest that is sure to satisfy your cherry craze.
Selecting trees: Tart cherries (Prunus cerasus), also called sour or pie cherries, are easy to grow. Use the tangy fruit for baking, or let it overripen on the tree for fresh eating. Sour cherries are self-fertile and will set fruit alone. They grow only 20 feet tall and bear fruit at an earlier age than sweet cherries. Sour cherries are hardy in Zones 4–7.
Sweet cherries (P. avium) do best in mild, dry climates, but cultivars have been developed that can grow well in other conditions. Most sweet cherries need a second compatible cultivar for pollination; shop carefully to be sure you get trees that can share pollen. If you have room for only one tree, choose a self-fertile cultivar such as ‘Stella’ or ‘Vandalay’; always look for cultivars that are suitable for your local climate and growing conditions. Sweet cherries can grow into trees 35 feet or taller, but they’re available on dwarfing rootstocks that will keep the trees as small as 10 feet. Most cultivars are hardy in Zones 5–7 and also thrive in Zones 8–9 in the Pacific Northwest.
Sweet cherries come in purple, red, and yellow. There are firm-fleshed types and soft-fleshed types. Soft-fleshed types tend to be less prone to cracking.
Duke cherries are hybrids between sweet and tart cherries and tend to be sweet/tart flavored and hardy in Zones 4–9.
So-called bush cherries such as Nanking cherry (P. tomentosa) and sand cherries (P. pumila and P. pumila ssp. besseyi) are relatives that bear small cherrylike fruit on shrubs and small trees. Many of these are better adapted to difficult growing conditions and harsh winters than cherry trees.
Rootstocks: Tart cherries are small trees no matter what rootstock they are grafted on. Standard sweet cherries are grafted on seedling root-stocks such as ‘Mazzard’ (P. avium ‘Mazzard’) and Mahaleb cherry (P. mahaleb). ‘Gisela’ rootstocks (Gisela 3, Gisela 5, Gisela 6, Gisela 12) are popular for their dwarfing effects; different selections are preferred in various growing regions. ‘Mazzard’ typically is recommended for heavy soils. Mahaleb rootstocks fare better in light soils and produce small trees that bear within 2 to 4 years of planting. For cherry-growing success, shop for trees from a nursery in your geographic region and on rootstocks that meet the particular growing challenges where you live.
Planting and care: Tart cherries grow well throughout much of the United States. They need about 1,000 chill hours below 45°F in winter. This limits their range to the Carolinas and northward through Zone 4. Although all cherries need well-drained soils, tart cherries tolerate moderately heavy soils better than sweet cherries. Space tart cherries 20 to 25 feet apart, sweet cherries 25 to 30 feet apart. Dwarf trees may be planted more closely.
Sweet cherries are not as winter hardy as tart cherries. Early autumn frosts also can damage sweet cherry trees. Commercially, sweet cherries grow best in the West, where summers are dry.
Cherries bloom early and are susceptible to frost damage. Sweet cherries bloom earlier than sour cherries. For site selection and frost protection ideas, see the Peach entry.
Once the fruit sets, watch soil moisture levels. Cherry fruit matures early and fast. It is particularly sensitive to moisture availability in the last 2 weeks of ripening. If the soil is too dry, the swelling cherries will shrivel. If it is too wet, they will crack and split. If you live in an area prone to heavy summer rainfall, choose cultivars that resist cracking. Spread a thick organic mulch out to the drip line to help maintain soil moisture at a constant level. Irrigate as necessary to keep the soil evenly moist.
Healthy cherry trees will grow about 1 foot a year. If your tree’s progress is slower or the new leaves are yellow, have the soil and/or foliage tested for nutrient deficiencies. See the Soil entry for instructions on taking a soil sample. Mulch each spring with a thin layer of compost out to the drip line. Don’t fertilize after midsummer. This could encourage new growth that won’t harden before fall frosts.
The Fruit Trees entry covers some important aspects of growing cherries and other tree fruits; refer to it for additional information on planting, pruning, and care.
Pruning: A central leader form is best for dwarf tart cherries. Use a modified central leader form for semidwarf and standard cherry trees. Spreading the branches while they are young will help control height and encourage earlier bearing. After the trees reach bearing age, prune to let light penetrate to the interior of the tree. Prune tart cherries lightly each winter to stimulate new growth and thin tangled branches. Prune sweet cherries less frequently, only every third or fourth year. Cut back heavy tops on overgrown sweet cherry trees to force new fruiting wood to develop on lower branches.
Problems: Fruit cracking and hungry birds are two of the biggest problems when raising cherries. Most insect and disease problems are less severe on tart cherry trees than on sweet. For information on pest control methods, see the Pests entry.
Birds can strip all the cherries from a backyard tree in very little time. Covering trees with netting before the fruit starts to ripen is the most effective way to stop bird damage. You can also try planting a mulberry tree nearby that fruits at the same time as your cherries to lure birds away from the harvest. See the Animal Pests entry for more ways to discourage feathered scavengers from stealing your cherries.
Cherry fruit fly, green fruitworm, peach tree borer, mites, and plum curculio all attack cherries. The chart, Fruit Tree Insects and Diseases, describes and lists controls for all of them. Aphids and scale can also cause problems; The Top 10 Garden Insect Pests lists descriptions and controls for both. Sawfly larvae (pear slugs) sometimes skeletonize cherry leaves; see the Pear entry for description and controls.
Shothole borers can attack cherries and other fruit trees. They make small holes in the bark of twigs and trunk. The holes are often covered with gum. The larvae are pinkish white and about ⅛ inch long. Prevent the tiny black adults from laying eggs by painting trunk and large branches in spring, summer, and fall with white latex paint diluted 1:1 with water. These pests most often attack wounded or diseased trees, so their appearance may be a sign that your trees are in trouble and you need to consider removing them.
Pear thrips can cause disfigured leaves and blossoms. Naturally occurring predatory mites usually provide control, but if your trees become severely infested, spray with insecticidal soap.
A few serious diseases pose problems for cherry trees. Be on the lookout for these common woes.
Brown rot and perennial canker attack cherries and other stone fruit; see Fruit Tree Insects and Diseases for descriptions and controls.
Black knot can infect cherries; see the Plum entry for details.
Cherry leaf spot appears as small purple spots on upper leaf surfaces. The spots later turn brown, and their centers may fall out. Leaves turn yellow and drop before autumn. Clean up and dispose of fallen leaves each winter. Plant resistant cultivars. If leaf spot is a problem in your area, plan a preventive spray program with lime sulfur or sulfur. Lime sulfur may discolor fruits, so don’t use it after young fruits begin to develop.
Powdery mildew can be a problem on cherries. See the Apple entry for description and control.
A number of viruses attack cherries. Buy virus-free stock and avoid planting in old cherry orchards or near wild chokecherries (P. serotina, P. virginiana).
Harvesting: When the fruit begins to drop, it is ready to pick. Tart cherries can be left to sweeten on the tree for a day or two.
To pick cherries, gently pull off clusters, keeping the stems on the fruit. Avoid tearing off the fruit spurs (small woody twigs to which the cherry stems are attached) or future crops may be diminished.
With as little as a 10- by 20-foot plot of land, you can grow eight Christmas trees in your backyard. In 6 to 8 years, you can harvest your own beautiful 6-foot Christmas tree. In addition to the personal pleasure of harvesting your freshly cut tree, you’ll be saving the dollars you’d have paid at a tree lot. Plus, fresh Christmas trees are recyclable and an eco-friendly alternative to artificial trees.
Choosing the right tree: Think about the kind of Christmas tree you usually buy. Is it fat and full-branched, or tall and spindly with plenty of room for ornaments to hang? Many commercial trees, especially the firs and pines, are carefully clipped for years to achieve the perfect Christmas tree look. Other species, such as balsam fir or eastern red cedar, are enjoyed imperfections and all.
Here are some popular Christmas tree types to get you started.
Long-needled: Scots pine (Pinus sylvestris), eastern white pine (P. strobus), red or Norway pine (P. resinosa), Austrian pine (P. nigra).
Short-needled: balsam fir (Abies balsamea), Douglas fir (Pseudotsuga menziesii), southern balsam fir or Fraser fir (Abies fraseri), Colorado blue spruce (Picea pungens), Norway spruce (P. abies).
Scaled needles: cypresses (Cupressus spp.), eastern red cedar (Juniperus virginiana).
Some Christmas trees like it hot. But some like it cold, some like it moist, and some like it dry. Ask your local nursery owner or Cooperative Extension office to recommend species that thrive in your area.
Planting and care: Plant your trees in an area of full sun, about 6 feet apart. Start by planting two or three small trees from 1- or 2-gallon pots the first year. Arrange trees in staggered rows for best use of space. Plant another tree or two each year until you’ve planted eight trees. Once you cut the first tree in 6 to 8 years, remove the stump the following spring and plant a new young tree. Remember, you will harvest them before they reach mature size. Evergreen trees require little or no fertilizer for healthy growth. Mulch with well-rotted manure around the selected tree a year before cutting, for deep green color.
If you want to shear your trees to encourage the classic Christmas tree shape, do so in spring. See the Evergreens entry for instructions on pruning and shearing.
Pine-tip moths and sawflies feed on and distort new growth. Check your trees closely for their caterpillar-like larvae, which may appear from May through September. Snip off damaged branch tips and destroy them. You can spray sawflies with insecticidal soap, or with pyrethrins or neem for severe infestations.
For more information on growing Christmas trees, you can find a grower in your area (search by ZIP code), research types of trees, find a tree-recycling program, and much more by visiting the National Christmas Tree Association’s Web site; see Resources.
Decorate a container-grown or balled-and-burlapped evergreen for Christmas, and then plant it outside to enjoy the memories it holds for many years to come. This sounds simple, yet the stress on the plant is so great that many ex-Christmas trees end up in the chipper. Keep in mind that balled-and-burlapped trees can be very heavy, so have a plan of action for moving yours.
A living evergreen tree’s chances for a successful transition from your living room to your yard are best if it remains indoors for only a few days. A longer stay will make the tree break dormancy and produce tender new growth. If this happens, keep your tree in a cool, sunlit room through winter, and treat it as a giant houseplant.
To enjoy a living tree for the holidays and beyond, follow this plan of action.
1.Dig a planting hole in late fall before the ground freezes. Fill the hole with loose straw. Save the soil—needed for later planting—in an area where it’s protected from freezing.
2.For best selection, choose your tree early. Store it in an unheated garage or outdoors.
3.A few days before Christmas, place the tree indoors, well away from heat sources. Check soil moisture daily.
4.After Christmas, remove the straw from the hole and plant the tree, using the reserved soil. Water thoroughly, and spray the needles with an antidesiccant.
Chrysanthemum, garden mum, daisy. Summer- and fall-blooming perennials, cut flowers.
Description: Chrysanthemum × morifolium (syn. Dendranthema × grandiflorum), garden or hardy mums, can bring brilliance to your autumn garden. They fall roughly into two groups: the 1- to 1½-foot mounded cushion mums sold in bloom seemingly everywhere in fall, plus some 2- to 3-foot upright types; and a huge range of specialist-favored exhibition cultivars. Florist’s mums, grown as potted plants, are frequently not hardy, and they need such a long season to flower that even where they’ll survive winter, they often won’t bloom before the first fall freeze. By far the best choices for most gardeners are those from the first group. Ranging in size from ½ to 4 inches, the mostly double, rounded flowers, in white, yellow, orange, red, rust, lavender, and purple, harmonize beautifully with their dark green, aromatic foliage.
Hundreds of years of selective breeding have resulted in five distinctive chrysanthemum bloom shapes: Button mums have small, tidy petals; daisy mums have daisylike flowers; decorative mums develop 2- to 4-inch-wide double flowers; football mums are oversize, with ruffly petals; and spider mums have long, thin, arching petals. Only decorative, button, and daisy types are reliably hardy in the garden. Zones 4–9.
Several beloved garden flowers have been reclassified and moved from the genus Chrysanthemum into other genera. One of the most popular is Leucanthemum × superbum (formerly Chrysanthemum × superbum), Shasta daisy, perhaps the quintessential daisy, with large, abundant, cheerful blooms. In early summer, plants display single to double, 2- to 4-inch white or cream flowers borne on stiff 1- to 2-foot stems atop elongated, shiny dark green leaves. The cultivar ‘Becky’ was named Perennial Plant of the Year for 2003 by the Perennial Plant Association. Zones 4–8.
Another popular reclassified plant is Tanacetum coccineum (formerly Chrysanthemum coccineum), painted daisy, named for its bold flower colors, also known as pyrethrum daisy. However, the better source of the popular botanical insecticide, pyrethrum, is a relative, Chrysanthemum cinerariifolium. Among gardeners, painted daisies are beloved for their flowers alone. Plants bear single to double 2- to 4-inch blooms in shades of white, pink, and red in early summer. The weakly upright, 2- to 3-foot flower stems rise above delicate lacy leaves up to 10 inches long. Zones 3–7.
How to grow: Start garden mums with rooted cuttings bought in spring, or divide last year’s clumps, replanting only the most vigorous pieces. You also can buy plants in bloom in fall and plant them directly into borders. Plant in full sun in average to slightly rich soil with excellent drainage; water during drought. Add a little extra fertilizer in late spring and midsummer. For dense plants with lots of flowers, pinch out the tips one or two times before July 15 in the North and August 15 in the South. Hose regularly to deter aphids and mites. To avoid nematode problems, don’t grow mums in the same place for more than a few years.
Plant or divide Shasta and painted daisies in spring or early fall in a sunny, average to slightly rich, very well-drained soil. Shasta daisies grow easily and quickly from seed, but seed-grown painted daisy plants may produce misshapen flowers. Painted daisies don’t ship well, so buy locally grown plants. After the flowers fade, cut plants back and fertilizer lightly to promote rebloom. Painted daisies benefit from support, such as from wire forms or twiggy branches, when in bloom.
Landscape uses: Plant garden mums in borders with other fall-blooming perennials like asters and goldenrods for a stunning autumn show. Their ornamental foliage and bushy habit make mums good foliage plants in a border, too. Mums are bold plants that make an impressive display in a bed by themselves or in containers on a patio or deck.
Grow Shasta daisies in masses throughout sunny borders and in cottage and cutting gardens. Their round flowers contrast nicely with spiky or mounded blooms. Grow painted daisies in informal settings and cottage gardens.
See Dasiphora
Citrus spp. and hybrids
Rutaceae
Citrus trees have shiny, evergreen leaves; fragrant flowers; and attractive, often tasty and persistent fruit. In northern climates, you can grow dwarf citrus trees in tubs and bring them indoors during winter. “Indoor-Outdoor Citrus” has more information about how to grow citrus trees in containers.
Selecting trees: There are so many types of citrus that you may have trouble deciding which to grow. Edible types include calamondin (× Citrofortunella mitis, also called × Citrofortunella microcarpa and Fortunella japonica), citrange (× Citroncirus webberi), citron (Citrus medica), grapefruit (C. × paradisi), lemon (C. × limon), Key lime (C. aurantiifolia), kumquats (Fortunella spp.), tangerine or mandarin orange (Citrus reticulata), orange (C. × sinensis), rangpur lime (C. × limonia), pomelo or shaddock (C. maxima), sour or Seville orange (C. aurantium), tangelo (C. × tangelo), and temple orange or tangor (C. × nobilis).
Consider the yearly range of temperatures and possible frost when making your selection. Local nurseries usually stock citrus trees that grow well in the area. The fruit of all types is easily damaged by frost, but the leaves and wood of some are more cold resistant than others. In general, limes are the least hardy, oranges slightly hardier, and calamondins and kumquats are the most hardy, withstanding temperatures as low as 12° to 15°F. Hardy orange (Poncirus trifoliata) is hardy into sheltered areas of Zone 5. It’s a thorny, deciduous tree that serves as an unusual ornamental, but its small yellow-orange fruit is not edible.
A single mature citrus tree yields more than enough fruit for a family. If you plant more than one tree of the same type, select cultivars with different harvest times, or plant different types of citrus so you won’t be overwhelmed with one kind of fruit. Almost all citrus are self-pollinating. A few hybrids are not; be sure to check for the kind you want when you buy.
Select sturdy nursery-raised trees. A 1-year-old tree should have a trunk diameter of ¾ inch. A 2-year-old plant should have a diameter of at least 1 inch. Those with fewer fruits and flowers are better because they have put more energy into sturdy top and root growth.
Rootstocks: Most commercially grown citrus fruits are grafted onto rootstocks. Trifoliate orange and sour orange are both good rootstocks where cold-hardiness is important. Sour orange is susceptible to nematode attacks and shouldn’t be used where they are a problem. ‘Milam’ lemon is a nematode-resistant rootstock. If you live in an area where salt accumulation in soil is a problem, choose a salt-tolerant rootstock such as ‘Cleopatra’ mandarin orange. Your local extension office can tell you what rootstock is best in your region.
Planting: Citrus do best at a pH of 6.0 to 6.5. They are not fussy about soil but do require good drainage. If drainage is a problem, plant in a raised soil mound about 1½ feet high.
Select a sheltered area with full sun, such as a sheltered, south-facing alcove of a building. Citrus flowers attract bees, so don’t plant them in high-traffic areas.
You can plant citrus at any time of year, but it’s best to plant container-grown trees in spring. Keep the graft union 6 inches above the soil surface when planting. Full-size trees require at least 25 feet between trees; dwarf trees need less.
Citrus bark is thin and easily sunburned. Wrap the trunk with commercial tree wrap or newspaper for the first year, or paint it with diluted white latex paint.
Care: In dry areas, water newly planted trees at least once a week for the first year. Once established, trees need less-frequent watering, but never wait until leaves wilt to water. Water stress can cause developing fruit to drop; prolonged drought causes leaf drop and may kill the tree. Water slowly and deeply; shallow sprinkling does more harm than good. In drought areas, construct a shallow watering basin that extends from 1 foot away from the trunk to 1 foot beyond the drip line. Or install drip irrigation under a thick layer of mulch to conserve water and protect shallow feeder roots. Keep mulch at least 6 inches away from the trunk.
In citrus-growing areas, soils often lack organic matter and nitrogen. Spread compost, well-rotted manure, or bloodmeal on the soil surface out to the drip line four times a year, beginning in February.
Pruning: Most citrus trees need little pruning beyond removing dead or broken branches. Limit the tree’s size by thinning out energetic shoots that outgrow other branches. Thin branches rather than shortening them. Remove suckers as soon as they emerge from the ground. See the Pruning and Training entry for instructions on correct pruning technique.
You can revitalize an old and unproductive citrus tree by pruning severely in early spring. Wear thick gloves if the tree has thorns. Cut off all branches 2 inches or larger in diameter flush to the trunk, and feed and water heavily for the next year. Very severe pruning may stop fruiting for up to 2 years.
Winter protection: Citrus are usually grown outdoors in climates where frost is rare: Zones 9–10 and the warmer parts of Zone 8. While some types of citrus are more cold-hardy than others, all citrus fruit is vulnerable when frost does occur. In areas where mild frosts are common, don’t plant cultivars that bear in winter and early spring. Since succulent new growth is more prone to frost injury, withhold fertilizer and extra water in late summer to limit new growth. When frost does threaten, cover trees with large fabric sheets. Use fans to keep air circulating around the trees. Symptoms of frost damage include yellow wilting leaves or greenish shriveled leaves. Should frost damage appear, wait until spring growth starts to see the true extent of damage. A tree that loses all its leaves can still rejuvenate. If damage is severe, dieback may continue during the growing season.
Harvesting: Citrus trees usually bear in 3 to 4 years. It can be hard to tell when citrus fruit is ready to pick. Color is not a good indicator. Fruit can have ripe coloration several months before being ready to harvest or may remain green and unappealing even when ripe and juicy inside. Use the taste test to determine when fruit is at its peak flavor. Allow fruit to ripen on the tree before picking.
Use pruning shears to cut stems close to the fruit when harvesting. Don’t just pull fruit off the tree. Ripe citrus fruit can remain on the tree for up to 3 months. Once harvested, citrus can be stored in the refrigerator for 3 or more weeks.
Problems: Citrus trees in the home garden are relatively untroubled by pests. Much of the damage that does occur is cosmetic and has no effect on the internal fruit quality. In dry climates, pests such as scale, whiteflies, mealybugs, thrips, and mites may cause problems. In humid climates, fungal diseases are more likely to cause problems.
Scale insects appear as small, hard bumps on leaves, twigs, and fruit. Sooty mold may be present. Predatory lady beetles attack scale. Summer oil spray also controls them.
Whiteflies suck leaf sap. Clouds of tiny white flies appear when foliage is disturbed. Fruit is pale and stunted. Leaves are dry and yellowing and may show black sooty mold, which grows on the honeydew excreted by the pests. Ladybugs, lacewings, and parasitic wasps help control whiteflies. Repeated strong water sprays knock whiteflies off trees. For added control, spray with insecticidal soap.
Thrips cause distorted, yellow-streaked new growth in spring. Blossoms turn brown, and developing fruit shows a ring at the blossom end. To reduce chances of thrips infestation, keep citrus adequately watered. Lacewings help control thrips. Neem oil can wipe out thrips if you catch an infestation early on. For severe infestations, apply insecticidal soap.
Mites cause pale leaves, sometimes with yellow spots. Fruit may have dark brown markings, and leaves may drop. Spray leaves with cold water regularly to remove dust, and provide adequate water. Ladybugs, lacewings, and predatory mites attack mites.
Mealybugs are white, cottony or waxy insects that feed on sap. They secrete honeydew, which attracts ants and encourages sooty mold. They are controlled by the mealybug destroyer, a ladybug type of beetle. Horticultural oil sprays also provide control.
Snails may climb trees and feed on leaves. Encircle tree trunks with a copper barrier strip to prevent snail problems.
Root rot can damage citrus trees. Too much fertilizer, cultivation, and gopher gnawing all can encourage the disease. Avoid injuring roots, and ensure good drainage.
Dead bark near the soil line and large amounts of gummy sap indicate foot rot. Keep the tree base dry and remove discolored wood. Foot rot problems can be avoided by providing good drainage at planting.
Viral diseases are a major problem in some areas. Purchase only virus-free trees.
Where cold winters preclude citrus in the garden, the attractive small trees make fine patio/sunroom plants. Indoors, they need a well-ventilated area with high humidity and at least half a day of full sun. During summer, a sheltered, partially shaded spot outdoors is ideal.
Select a container that is deep and wide enough for the tree you choose. A calamondin will fruit in a 10-inch pot, a ‘Meyer’ lemon will grow to 6 feet in a 5-gallon pot. If you plan to move them in and out, choose containers you can handle easily. Or mount wooden planters on casters; set other heavy containers on wheeled stands. Citrus need loose, well-drained potting mix and benefit from the addition of bonemeal. The Container Gardening entry gives guidelines for selecting suitable containers, preparing planting mixes, and caring for plants.
Citrus need warm days (70° to 75°F) and cool nights (45° to 55°F) during winter. During summer, they like it as warm as possible. If you move your trees indoors during winter and outdoors during summer, acclimatize them by setting containers in an intermediate area for a few days so they can adjust gradually. Leaf burn may occur with sudden climate changes.
Don’t let the potting mix dry out. Water whenever the top ½ inch of potting mix starts to dry out. Water thoroughly until water drains from the bottom, but don’t let the plant sit in water. At least once a month, water with liquid fertilizer such as seaweed extract. Mist leaves frequently, and group plants to conserve humidity.
If your citrus flowers indoors, you’ll need to pollinate it by hand for a good fruit set. Take a small artist’s brush or a cotton swab and transfer pollen from one blossom to another. Giving the plant a slight shaking also transfers pollen.
Container-grown citrus need a light yearly pruning. Thin out entire branches rather than shortening them, or you’ll get a flush of new branches sprouting below the cut. When plants become rootbound, repot in fresh potting mix in a larger container. To keep the plant small, prune off circling roots and cut back some of the remainder. Shake out as much of the old potting mix as you can, repot in fresh mix, and cut back top-growth by about one-fourth.
Many citrus are naturally dwarf and adapt well to container culture. Suitable types and cultivars include calamondin, ‘Owari Satsuma’ mandarin, ‘Improved Meyer’ lemon, ‘Eureka’ lemon, ‘Bearss’ seedless lime, Key lime, ‘Eustis’ limequat, ‘Washington navel’ orange, ‘Nagami’ kumquat, ‘Moro’ blood orange, ‘Oroblanco’ grapefruit, and rangpur lime.
Clematis. Perennial or woody vines.
Description: Clematis are mostly twining woody vines, growing 5 to 18 feet long. Most are deciduous with lobed or trifoliate leaves made up of toothed leaflets. Feathery seed heads follow the blooms and linger into early winter. The popular large-flowered hybrids, familiar to many gardeners, have showy 3- to 6-inch flat blooms and come in many shades of blue, purple, red, pink, white, cream, and yellow. Zones 4–9. Species clematis are less widely grown but also desirable. Their delicate blooms, shaped like saucers, stars, or bells, are delightfully different from common garden flowers. Many of them are vigorous enough to use for screening.
Clematis armandii, Armand clematis, is one of the few evergreen clematis with large leaves. It is fast growing (to 10 feet) with fragrant, white, star-shaped blooms in late spring. Zones 7–10. Grow C. heracleifolia, a perennial (herbaceous) clematis, with light staking for support. It bears clusters of fragrant, blue, 1-inch flowers in late summer. Zones 3–8. C. macropetala, big-petal clematis, is a vigorous vine (to 12 feet), with nodding double blooms of blue, pink, or white in spring. Zones 3–7.
C. terniflora (also known as C. maximowicziana and C. paniculata), sweet autumn clematis, is a vigorous nonnative invasive vine from Japan (to 7 feet) that is covered with fragrant, white, 1-inch blooms from August through October. Zones 4–9. Native C. virginiana, virgin’s bower or devil’s darning needles or woodbine, is an excellent native substitute. It bears white flowers on vines to 20 feet in late summer and fall. Zones 4–8. C. montana, anemone clematis, is also a vigorous vine (to 20 feet), with white or pink 2½-inch open flowers in May and June. Zones 6–8.
C. tangutica, golden clematis, is a strong climber (to 15 feet) with bright yellow, 3- to 4-inch nodding flowers borne in June and July. Zones 2–8. C. texensis, scarlet or Texas clematis, is a vigorous vine (to 9 feet) with scarlet 1-inch bell-shaped blooms from midsummer through frost. Zones 4–8.
How to grow: Transplant container-grown clematis plants in spring or fall. Plant in moist, well-drained soil. Give the roots cool conditions, but plant in full sun. (To achieve this seemingly contradictory goal, plant clematis where the roots will be shaded by a nearby shrub, or mulch well.) Research has found that clematis don’t need additional lime; ignore advice to the contrary. Plant where a support is available for the vine to twine around—a pillar, tree trunk, or trellis will work well. Clematis stems break easily, so install your trellis or stake before planting.
Clematis wilt is the only serious problem of clematis. When the fungus attacks, the entire plant or afflicted branch will droop and shrivel. Remove all diseased parts, even if it means cutting the plant to the ground. Plants may recover, resprouting from the roots. Good sanitation is important, as the fungal spores can overwinter on dead leaves. Do not add infected material to the compost heap—burn or otherwise destroy it. Do not replant a clematis in a site where wilt has been a problem.
Some clematis bloom on old wood (growth from previous seasons), while others bloom on the current year’s growth. For clematis that bloom on old wood, thin or shape them immediately after flowering. Heavily prune clematis that bloom on new wood in late winter or early spring before bud break. (Ask the seller which type of clematis you’re buying.) Remove all dead shoots and trim vines back to the first pair of plump buds. Untangle vines growing on walls and tie them to a trellis in a fan pattern.
Landscape uses: Large-flowered clematis are ideal for growing on walls, fences, arbors, and posts, or up through shrubs. Most of the species are very vigorous and create good screens. You can use the herbaceous perennial clematis in a perennial or mixed border.
See Season Extension
See Celosia
Cold frames and hotbeds give gardeners some control over the one thing most beyond their control—the weather. By creating an area of close-to-ideal conditions right where the plants need them, cold frames and hotbeds help gardeners stretch the seasons and make it possible to grow plants accustomed to warmer climates. A cold frame can add a month or more to each end of the growing season, and in warmer climates can enable gardeners to grow plants outdoors through winter.
Gardeners most commonly use cold frames in early spring for starting or hardening off seedlings or transplants destined for the garden. However, there are many other uses for cold frames. A moist, shady frame provides a good start to fall crops in the dry heat of summer; in winter, the same frame offers a spot for cold-treating spring bulbs for forcing. A cold frame also may be useful for rooting cuttings of woody plants or perennials taken any time of year.
A traditional cold frame is a rectangular, boxlike structure, with sides made from boards, plywood, bricks, or concrete blocks, supporting a glass top that might be made of old windows. Other suitable, light-admitting covers for a cold frame include fiberglass, Plexiglas, or heavyweight polyethylene tacked to a frame. Gardeners use blocks, sticks, or a solar-powered vent (available from garden supply companies) to prop the lid open for ventilation.
The lid’s size usually determines the dimensions of the cold frame, especially if the lid is a recycled window. Still, it should be larger than 2 by 4 feet to hold enough plants to make it worthwhile, and not much larger than 3 by 6 feet so the plants within are easy to reach. Build the back wall 4 to 6 inches higher than the front so the lid slopes forward to maximize the amount of light that reaches the plants inside and allow snow and water to slide easily off the lid. A white or light-colored frame interior increases the amount of light reflected onto the plants.
Cold frames are essentially passive solar collectors. To get maximum benefit from the heat and light of the sun, a frame’s sloping lid should face south—southeastern or southwestern exposures are the next best choices. Ideally, the site should receive full sun from midmorning to midafternoon during winter and early-spring months. Hotbeds need a full-sun exposure as well.
Build a cold frame on a site that is fairly level and well drained. If possible, place the frame with its north side next to a building, fence, or hedge for protection from winter winds. Select a site that is near a water supply and is easy to monitor year-round. Deciduous trees overhead aren’t necessarily bad; they’ll provide summer shade without blocking winter sun.
A cold frame may be permanent or portable. Permanent frames are built over foundations that are either dug into the ground or constructed on the surface. Aboveground models provide less frost protection than ones built over a dug foundation, but both provide more reliable protection from the cold than portable frames. Permanent frames generally are sturdier and longer lasting.
Portable frames, which are basically bottomless boxes with clear lids, function in much the same way as permanent frames. These are often available ready-made from Web sites and catalogs that sell greenhouse supplies. Many models are collapsible for storage when not in use. However, their reduced insulating capacity makes them subject to wider temperature fluctuations. In the vegetable garden, portable frames can extend the season for spring or fall crops such as lettuce or spinach, or keep frost off late-ripening crops. In areas with mild winters, use them to grow winter crops of cold-tolerant vegetables. Placed over garden beds, portable frames will provide adequate winter protection for many perennials. In summer, use a portable frame to create a cool, shady spot for seedlings.
Hotbeds and cold frames are structurally identical, except that hotbeds contain a source of artificial heat. Traditionally, rotting manure served as the heat source, but today, electric heating cables typically provide the warmth. Because hotbeds have a steady source of heat, they can be used earlier in the season than most cold frames, and they create ideal conditions for starting most types of seeds.
Make any frame with a dug foundation into a hotbed by adding an electric heating cable. You can also use portable frames, although they don’t conserve heat as well as permanent frames, but you need a pit at least 1 foot deep to hold most heating cables. For best control over temperatures within the frame, select a heating cable with a thermostat.
To make a hotbed, spread a 2-inch layer of vermiculite on top of a gravel layer at the bottom of your pit or dug foundation. Spread the cable on the vermiculite, using long loops to evenly distribute the heat. Don’t let the cable wires cross; keep loops at least 8 inches apart and 3 inches away from the frame edges. Cover the cable with 1 inch of sand, followed by a layer of screen or hardware cloth to protect it from digging tools or other sharp objects. Cover the screen with 4 to 6 inches of coarse builder’s sand in which to sink pots.
A modern hotbed. A heating cable sandwiched between a layer of vermiculite and a layer of sand will transform a cold frame into a hotbed, letting you start seeds outdoors even earlier.
Ensure success by carefully monitoring the conditions inside your hotbeds or cold frames. As with any gardening situation, the plants require proper light, moisture, and temperature levels.
Temperature control: The key to using a cold frame successfully is keeping it cool, not warm. The temperature inside the cold frame should stay below 75°F for summer plants and below 60°F for plants that normally grow in spring and fall. The way to keep temperatures cool inside a cold frame is to lift the lid to vent the frame.
Venting a cold frame is necessary even in winter, because on a sunny winter day, whatever the outdoor temperature, the temperature in an unvented, insulated frame can rise to 100°F or more. A thermometer, placed in a shaded spot in the frame, is a must for determining when to vent. A good rule of thumb: On sunny days when outdoor temperatures are above 40°F, prop the lid open 6 inches; if outdoor temperatures rise above 50°F, remove the lid. Make sure you close the lid or put it back on the frame in late afternoon to trap heat inside for the cold night to come. Solar-powered automatic openers, triggered by temperature, will vent the frame when you aren’t home, but it’s best to learn the temperature nuances of your frame as well. A thermometer with a remote sensor gives you the welcome option of monitoring the temperature from indoors on sunny but cold winter days.
In unusually cold weather, or if you have an uninsulated, aboveground frame, bank bags of leaves, bales of hay, or soil around the frame. Stack bricks or plastic gallon jugs filled with water against the inside of the north wall as passive solar collectors; enhance the heat absorption of either with a coat of black paint. Both will absorb heat during the day and release it at night, as will black garbage bags of leaves piled against the outside of the frame. If it’s going to be a frigid night, insulate the glass lid before dark by covering it with old blankets, newspapers, bags of leaves, or straw bales. Snow is also a good insulator, but brush heavy snow off the glass so it doesn’t break.
Watering: Until you become familiar with the conditions in your frame, check plants frequently to be sure they have enough water. This is especially important in warm weather when plants are actively growing. Check the moisture of the soil at a depth of between 1 and 1½ inches; for most plants, soil should remain constantly moist, but not soggy. Water whenever plants look droopy, but avoid watering on cold, cloudy days. To discourage fungal diseases, water early in the day. Use water that’s about the same temperature as the growing medium, because cold water can shock plants and slow their growth. If you have dormant plants in your frame that you plan to store there over winter, water them thoroughly for the last time 2 weeks before the first fall frost is predicted, then check moisture every few weeks.
Containers: Growing plants in containers has several advantages over planting directly in soil in the frame. Plants in containers can easily be added, moved around, or removed without disturbing the frame’s other inhabitants. Soil mixes can be customized to suit individual plants, as can watering and fertilizing schedules, so the frame can hold a variety of plants. Also, using individual pots helps control diseases, which can spread quickly in frames. Place pots on the layer of gravel at the frame’s bottom, or sink to the rims in 4 to 6 inches of sand over the gravel.
Pests and diseases: Check your frame regularly for evidence of disease or insect infestation. In mild weather, uncontrolled insects, slugs, or other pests can thrive in a cold frame or hotbed. Before placing a pot in the frame, check it for hitchhiking pests.
The warm, moist conditions inside a frame may also encourage plant diseases. Generous spacing and proper ventilation can help prevent disease problems. Remove and discard infested, diseased, or sick-looking leaves and plants as soon as you spot them, because problems spread rapidly.
If serious problems develop, remove all plants and sterilize the inside of the frame. To sterilize, pour boiling water into the gravel and/or sand at the bottom of the frame, or leave the glass lids tightly closed during summer to allow heat to build up inside the frame. If you grow plants directly in soil at the bottom of your frame, it is a good idea to dig it out completely every 2 to 3 years and replace it with fresh soil.
Frame maintenance: The moist, warm environment inside a frame subjects it to rapid deterioration. If paint starts flaking, repaint as soon as the frame is free of plants. Let a newly painted frame air for several weeks before putting plants in it, to avoid exposing plants to potentially harmful fumes. Recaulk as necessary to maintain airtight conditions. Keep the sash and inside of the frame clean to increase the amount of light available to plants.
Spring ritual. Harden off seedlings in your cold frame in spring before planting them out in the garden. Use a notched wooden support or install a solar-powered automatic opener to vent the frame on sunny days.
The uses you find for your frame depend not only on what your gardening needs are but also on where you live, what exposure you have available, and what type of frame you select. Experiment to find the best ways to use your cold frame and/or hotbed, as well as the best seasonal schedule for your area.
Spring: To harden off seedlings started indoors, move them to a cold frame a week or two before they’re scheduled for transplanting. Gradually open the lid for longer periods each day. To keep the seedlings from suffering sunburn, shade them at first by using wood lath or burlap or by painting the glass with a mixture of clay soil and water. Expose them gradually to full sun.
Cold frames are also good places to germinate seeds in early spring—especially those of cold-tolerant vegetables, perennials, and annuals. Sow seeds in flats or pots placed directly in the frame about 2 months before the last spring frost date. For an even earlier start, sow seeds in a hotbed or indoors, and move seedlings to a cold frame after their first transplanting. This frees up space for more tender plants indoors and eliminates the succulent, rank growth of seedlings grown in warm temperatures. Later in the season, sow tender annuals in the frame.
Where the growing season is short, use a cold frame to start long-season plants such as melons that otherwise might not mature, or plant very early spring crops of lettuce or spinach.
Summer: During summer, store the glass cover for your cold frame in a protected place and substitute screens to keep out leaves and debris. In late summer, use a frame shaded with a grid of wood lath over the screens to start fall crops of heat-sensitive vegetables such as lettuce. Raise seedlings in pots or flats, then transplant to the garden when temperatures begin to cool. Summer-sown perennials or biennials can be germinated in pots or flats, held over their first winter under the cold frame, and moved to the garden the following year. Root woody and herbaceous cuttings in a lath-shaded frame. The contained environment provides ideal rooting conditions.
Fall and winter: As the days shorten and temperatures drop, replace the glass lid, and your cold frame becomes an ideal place to sow seeds of hardy annuals, perennials, wildflowers, shrubs, or trees. With seed sown in fall or early winter, the object is not to germinate the seed immediately but to provide a cold treatment so it will germinate the following spring. Sow seed just before the ground freezes so it doesn’t germinate before winter arrives.
Fall crops of lettuce and spinach can thrive in cold frames well after the first frost. Fall is also the time to move perennials, herbs, and container-grown plants that might not be quite hardy outdoors under cover for winter protection. Dig semihardy herbs such as lavender and rosemary from your garden and keep them in a cold frame over winter. You can also use your cold frame for giving pots of hardy spring bulbs such as daffodils and crocus a cold treatment before forcing them into bloom. See the Bulbs entry for complete instructions.
See Plectranthus
Brassica oleracea, Acephala Group
Brassicaceae
A popular staple of Southern cuisine, collards are quite cold resistant. A touch of frost mellows the flavor of the wavy broad green leaves and, although col lards tolerate heat better than many cabbage-family crops, in the South, collards grow best in late fall, winter, and early spring.
Planting: Sow seeds ¼ inch deep in spring, 4 weeks before the last expected frost. Space seedlings 1 foot apart in rows 3 feet apart. For a fall crop, broadcast seed 8 to 10 weeks before the first expected frost; thin to 12 inches apart.
Growing guidelines: Foliar feed with liquid seaweed extract two or three times during the growing season.
Problems: See the Cabbage entry for disease-and insect-control measures.
Harvesting: Start picking outer leaves when plants are 1 foot tall. Frosts improve flavor without harming collards.
See Aquilegia
On abandoned lots and at schools, office parks, retirement centers, and churches in thousands of diverse locations across North America, gardeners without land of their own and those who want to beautify their neighborhoods come together to create community gardens. Some are strictly ornamental, but many produce food for the members themselves and for needy people in the community. All bring a variety of benefits to the participants and to the surrounding area. The benefits include:
Providing fresh, healthful produce for people in areas where it is not often found.
Creating a quiet green space where residents can relax and find respite from the stress of daily life.
Bringing together people of different ages, backgrounds, and income levels to work collaboratively for the good of their neighborhood.
Improving safety—studies in St. Louis, Chicago, and other cities found that people living near community gardens suffer less crime and domestic strife than those who don’t.
Many European cities offer residents small plots (called “allotments”) in the surrounding area where gardeners can enjoy the experience of sowing and growing. But in the United States and Canada, community gardens are typically organized and led by local volunteers. Often, members have individual plots where they grow food for themselves, but in some gardens the group shares all the labor and the harvest.
In most North American cities, municipal parks departments and/or nonprofit organizations provide support and resources to community garden groups. If you want to start a community garden where you live, get in touch with the American Community Gardening Association (communitygarden.org), a national organization of gardening and open space volunteers and professionals. It offers programs and support for community garden volunteers.
There are many details to work out in launching a community garden, but they can be divided into these broad steps.
It takes a community to start a community garden. You’ll need at least one or two superorganized people to recruit neighbors with a shared passion but varying ages, backgrounds, and skills. At every step, include the people who will benefit from the garden in the planning process.
In some cities, online maps like Living Lots NYC identify open spaces. Property-records departments help decipher lot ownership; private owners may lease land. Many locales have agencies that rent out public land for gardens. Terms can vary, so learn local laws and explore options for longevity, including establishing a trust. Get permission and a written lease to use any space. If your garden plan includes physical improvements such as fencing, creating raised beds, or adding soil, try to obtain at least a 3-year lease. Your group needs to be able to use the site long enough to justify its investments.
Individual or shared beds? Edibles or botanicals? Structured leadership or consensus? Agree on your purpose, garden design, and shared values. All gardens start with dirt. In cities, where contaminants are prevalent, soil testing and remediation are a must. If you’re growing edibles, bring in fresh soil and build raised beds out of wood or concrete blocks. Then set up a composting system to fertilize soil. Mulch is handy for weed-free pathways between beds. Gardens on old tenement lots often have leftover brick for public walkways. In wet climates, opt for gravel or permeable paving. Water is a necessity. Locales like New York City provide hydrant access, but rain barrels help conserve municipal supplies. Shaded seating and communal areas welcome neighbors and give relief to sweaty gardeners. A grill or outdoor kitchen facilitates gatherings; many gardens host workshops and performances. In others, the arts are integrated through sculptures and murals. Invite wildlife in with trees and maybe a landscaped pond with a fountain powered by solar panels. Good fences make good neighbors, and a sign that states the garden’s name, hours, contacts, and calendar says, “We’re here!” Where theft is prevalent, a lock on the gate is essential. You’ll want one on the tool-shed, too. Fence-side ornamentals—especially native flowering shrubs that attract pollinators or help feed the residents of your bee boxes—beautify the neighborhood. And since kids are the future of the movement, dedicated children’s beds help pass on the skills.
Many municipalities have grants programs for gardeners. Banks and other local businesses might also sponsor you. You’ll find more options at the American Community Gardening Association (ACGA) Web site. (See Resources.)
Botanical gardens and parks outreach programs often help with soil, seeds, equipment, and building materials as well as guidance on organic growing. Test and remediate soil and create ways to recycle and conserve, including composting and rainwater harvesting.
If your group needs horticultural information or other gardening support, contact the Cooperative Extension Service (there’s an office in every county), garden clubs, or garden centers. To learn more about managing a community garden, check the ACGA Web site.
Local officials, media, and members of the community can all support and enjoy your efforts.
Planting marigolds and herbs among the vegetables in your garden to confuse or repel plant pests is a well-known example of the practice of companion planting. Garden lore contains hundreds of recommended plant combinations, such as nasturtiums planted amid cucumbers to repel cucumber beetles or the traditional “three sisters” practice of growing corn, beans, and squash together to take advantage of complementary growth habits.
Modern research substantiates the effectiveness of some companion plants in repelling pests or attracting pest predators and parasites. However, the mechanisms that cause a plant to repel or attract pests remain largely unverified, and many companion planting practices represent a combination of folklore and fact. Evidence from scientific studies and gardeners’ experimentation indicates several possible ways in which companion planting works.
Masking or hiding a crop from pests
Producing odors that confuse and deter pests
Serving as trap crops that draw pest insects away from other plants
Acting as “nurse plants” that provide breeding grounds for beneficial insects
Providing food to sustain beneficial insects as they search for pests
Creating a habitat for beneficial insects
Whatever the cause, it does seem clear that areas planted to a single crop (monoculture) attract more pests than beds of mixed crops or those that are interplanted with herbs and flowers. It’s fun to try your own companion planting experiments and see what works in your garden.
Research has shown that night-flying moths (the adults that produce destructive larvae such as cutworms and caterpillars) approach flowers by flying upwind. If netting is placed over flowers, the moths will still land and feed, indicating that they react to flower odor. However, moths won’t land on colored flowers that lack a noticeable aroma. This explains why strongly scented companion plants such as marigolds may protect plants from pests. If pests can’t smell your prize plants, or if the scent isn’t right, they may go elsewhere to feed and lay eggs.
Popular plant choices for repellent or masking fragrances include the following:
Marigolds: Plant them as thickly as you can in a vegetable garden, but keep in mind that unscented marigolds won’t work for this trick. Make sure you choose strongly scented species and cultivars, such as French marigold (Tagetes patula).
Mints: Cabbage pests and aphids dislike peppermint and other members of this fragrant family. Since mints can grow out of control, set potted mints around your garden or plant them in areas where their growth can be controlled.
Rue: Oils from the leaves of rue (Ruta graveolens) give some people a poison-ivy-like rash, so use this low-growing plant with care and wear gloves when handling it. However, what annoys people also deters Japanese beetles. Grow rue as a garden border or scatter leaf clippings near beetle-infested crops.
Sweet basil: Interplant Ocimum basilicum in vegetable or flower gardens, or chop and scatter the leaves to repel aphids, mosquitoes, and mites. Use pots of basil on patio or picnic tables to discourage flies from joining outdoor activities.
Tansy: Used as a mulch, tansy (Tanacetum vulgare) may cause cucumber beetles, Japanese beetles, ants, and squash bugs to go elsewhere for a meal. It attracts imported cabbageworms, however, limiting its appeal as a repellent, and it can be invasive. If you’re already growing it in your garden, using it as a mulch around veggies other than cabbage-family crops is a good way to keep its growth in check while benefiting your crops, but don’t plant it just for this purpose.
There are many other interplanting options, too. Don’t forget that simply interplanting crops from different families helps deter pests. Adding fragrant plants to the mix will up the ante. Try the following combinations in your garden.
Plant basil and/or onions among your tomatoes to deter tomato hornworms.
Combine thyme or tomatoes with cabbage plantings to limit flea beetles, cabbage maggots, white cabbage butterflies, and imported cabbageworms.
Sow catnip by eggplant to discourage flea beetles.
Set onions in rows with carrots to impede rust flies and some nematodes.
Grow radishes or nasturtiums with your cucumbers for cucumber beetle control.
Grow borage with tomatoes, cucumbers, and strawberries to repel pests and attract beneficials.
Grow cilantro with spinach to repel aphids and attract beneficial tachinid flies.
Grow summer savory with beans to repel bean beetles.
Alternate double rows of corn with double rows of snap beans or soybeans to enhance the growth of the corn.
Interplant peanuts with corn or squash to increase the yields of both crops.
Plant spinach, lettuce, or Chinese cabbage at the base of trellised peas, where they benefit from the shade and wind protection.
Grow tomatoes, parsley, or basil with asparagus to help control asparagus beetles.
Nasturtiums also deter whiteflies and squash bugs, but they are more often used as a trap crop for aphids, which prefer nasturtiums to other crops. Planting a ring of them around apple trees limits woolly aphid damage to the trees (although the nasturtiums won’t look too great). Zonal geraniums (Pelargonium spp.) and petunias work the same way to lure Japanese beetles from roses and grapevines. Petunias will also act as a trap crop for beetles and aphids when planted among cucurbits (cucumbers, pumpkins, and squash).
Research into the facts behind companion planting folklore shows that many practices derive their success from naturally occurring compounds within the plants. As these compounds are isolated and identified, the preferred companion plants of past gardens may become the source of modern-day botanical controls.
Here are some results of scientific studies of companion plants and natural compounds.
•A potato plant grafted onto a tobacco plant root becomes resistant to the destructive Colorado potato beetle.
•A mustard oil extracted from turnip roots effectively deters pea aphids, Mexican bean beetles, and spider mites.
•African marigolds (Tagetes erecta) exude a chemical called thiopene from their roots that repels soil nematodes.
•The presence of asparagus roots in the soil leads to a decline in the stubby root nematode population.
•Growing collards as a trap crop effectively protects cabbage from diamond-back moth larvae.
•Boston fern leaves contain a feeding deterrent effective against southern armyworm.
•A chemical found in tomato plant leaves is toxic to some weevil species.
The idea of gardening to attract insects may seem odd, but in the case of beneficial insects, this companion planting technique can really pay off. Beneficial insects are a boon to the garden in two ways: They help control pests, and they assist in crop pollination. Although some beneficials feed on pests, nearly all need host plants to provide food and shelter during some or all of their life cycles.
Many beneficial insects are quite tiny and have short mouthparts. They can’t reach deeply into flowers for food. Plants with numerous, small flowers, containing easy-to-reach pollen and nectar, provide the necessary high-protein and high-sugar meals that support beneficial insect populations.
Help beneficial insects get a jump on early spring aphid activity by planting gazanias, calendulas, or other small-flowered plants that will grow in your area despite early-season cool weather. Beneficial insects need a series of blossoms to sustain them from spring until fall.
Herbs such as fennel, dill, anise, and coriander are carrot-family members that produce broad clusters of small flowers attractive to beneficials. Grow these culinary items near your vegetables to keep parasitic wasps nearby. Composite flowers such as sunflowers, zinnias, and asters also attract beneficials and have a longer season of bloom than carrot-family herbs.
Use this list of plants and the beneficials they attract to lure these useful insects to your garden.
Achillea spp. (yarrows): Bees, parasitic wasps, hoverflies
Angelica archangelica (angelica): Lady beetles, lacewings
Chamaemelum nobile (Roman chamomile): Parasitic wasps, hoverflies
Iberis spp. (candytufts): Syrphid flies
Ipomoea purpurea (morning glory): Lady beetles
Nemophila menziesii (baby blue eyes): Syrphid flies
Oenothera biennis (common evening primrose): Ground beetles
Solidago spp. (goldenrods): Lady beetles, predaceous beetles, parasitic wasps
For more on attracting and encouraging these tiny garden allies, see the Beneficial Insects entry.
Inside a compost pile, billions of bacteria, fungi, and other organisms feed, grow, reproduce, and die, recycling kitchen and garden wastes into an excellent organic fertilizer and soil conditioner. This process of decomposition occurs constantly and gradually in nature. When you build a compost pile, you’re simply taking advantage of—and accelerating—nature’s process to create an invaluable soil amendment for your garden.
Composting offers benefits to both the environment and your pocketbook. By making compost, you’ll reduce or eliminate the need to buy fertilizers. Compost improves soil structure and moisture retention and can actually protect plants from certain diseases. Composting leaves and other yard wastes is the environmentally responsible—and money-saving—alternative to sending them to a landfill or incinerator. Plus, as much as three-quarters of your household waste is compostable, too.
Your goal in building a compost pile is to provide conditions in which a “microherd” of composting organisms will thrive. Composting organisms’ needs are simple: a balanced diet of carbon and nitrogen, moist conditions, and a steady supply of oxygen.
To build a compost pile, gather a variety of organic materials—leaves, seed-free pulled weeds, straw, and vegetative kitchen scraps, for example—and heap them together in a pile. Add some rich garden soil or finished compost to “seed” the pile with composting organisms, and moisten everything thoroughly. Then step back and wait: The organisms will go to work digesting the organic materials in the pile. Several months later, you’ll have finished compost.
Check your compost pile occasionally to make sure it hasn’t dried out or become too wet. If you wish, you can also speed up the composting process by turning and mixing the materials occasionally. Read on to learn more about how and why composting works and how you can get the best results possible from your composting efforts.
Begin your search for compost ingredients in your own backyard, kitchen, and neighborhood. You probably won’t have to travel far to find a wealth of great composting materials. You’ll be looking for two types: “browns” and “greens.” Brown materials are high in carbon, and carbon compounds are what composting organisms “eat” in order to keep functioning and reproducing. Green materials contain relatively high amounts of nitrogen. Microorganisms need nitrogen for reproduction, because nitrogen is a basic building block of their cell structures.
High-carbon, “brown” ingredients are almost always plant materials: straw and dry leaves are two common “browns.” Many “greens” (nitrogen sources), such as manure and bloodmeal, come from animals, although fresh plant matter, such as grass clippings, is also nitrogen rich. High-nitrogen materials tend to be moist and often sloppy, but they’re not always green in color (manure and coffee grounds are just two examples of “green” compost ingredients that are brown). In general, high-carbon materials are brown or yellow, dry, and bulky. Straw is a classic example, but the output from your home office paper shredder qualifies as compost fodder too!
Aerobic. Describes organisms living or occurring only in the presence of oxygen.
Anaerobic. Describes organisms living or occurring when oxygen is absent.
Composting. The art and science of combining organic materials under controlled conditions so that the original raw ingredients are transformed into humus.
C/N ratio. The proportion of bulky, dry, high-carbon materials to dense, moist, high-nitrogen materials. The ideal C/n ratio for stimulating compost organisms is 25–30:1; finished compost’s C/n ratio is about 10:1.
Cold, slow, or passive pile. A compost pile that receives little or no turning, allowing some anaerobic decomposition to occur; composting proceeds slowly and at cooler temperatures.
Hot, fast, or active pile. A compost pile that is turned or otherwise aerated frequently, stimulating high temperatures and producing finished compost in a relatively short time.
Sheet composting. Layering undecomposed organic materials over the surface of a garden bed, typically at the end of the growing season, giving them time to decompose before working them into the soil the following spring.
Use these lists as a guide to choosing composting materials for your pile. Keep in mind that a small amount of a super-carbon-rich material like sawdust (500:1) will change the carbon-nitrogen ratio of your pile just as much as a large amount of straw, which is only 80:1.
| HIGH-CARBON MATERIALS | C/N RATIO |
| Leaves | 80:1–40:1 |
| Straw | 80:1 |
| Pine needles | 110:1–60:1 |
| Paper | 170:1 |
| Sawdust | 500:1 |
| HIGH-NITROGEN MATERIALS | C/N RATIO |
| Alfalfa hay | 12:1 |
| Table scraps | 15:1 |
| Grass clippings | 19:1 |
| Manure, rotted | 20:1 |
| Timothy hay | 25:1 |
| Weeds, freshly pulled | 30:1 |
| Fruit wastes | 35:1 |
C/N ratios. The proportion of carbon to nitrogen in a material (or a compost pile overall) is called the C/N ratio. You can use it as a benchmark for mixing composting materials in the right amounts. If the C/N ratio of a compost pile climbs too high (excess carbon), microorganisms will run out of nitrogen and won’t be able to reproduce. Their population size will drop quickly, so composting activity will slow down. Conversely, if the C/N ratio dips too low (too little carbon), the microorganisms won’t have a sufficient energy source, so they’ll stop working. In this case, the compost pile may start to smell bad as the unused nitrogen in the pile escapes into the air.
The ideal C/N ratio for a compost pile overall is 25–30:1, and if you’re good at math, you can do some fancy calculating to figure out an ideal mix. Refer to the chart below for specific C/N ratios of common compost materials. The chart is also useful even if you prefer a less precise approach: Simply aim for a mix of two parts high-carbon materials to one part high-nitrogen materials (you can use a trash can, garden cart, or 5-gallon bucket as your unit of measure).
Most organic materials supply a wide range of other nutrients needed by compost organisms and plants, too, and so the greater the variety of materials you include in your compost pile, the better the end product will be. You can also mix in mineral-rich materials such as rock phosphate or greensand to tailor the nutrients in your compost to match the needs of your soil and plants. See the Fertilizers entry for information on mineral sources you can add to your compost pile.
Building a compost pile is as simple as clearing a site and heaping up materials, but many gardeners like to put their compost in some type of enclosure. Compost bins are made of wood, plastic, concrete, bricks, or just about any durable, weatherproof material. Whether permanent or portable, bins can protect compost from the weather, conserve heat during composting, and keep out scavenging animals.
You can also collect composting materials inside a ring of wire fencing or a wood-and-wire frame as shown at right. These structures are useful for piles you want to turn frequently and also for building piles in sequence. To turn the compost, you simply unfasten the enclosure and then reposition it next to the pile of composting materials. Then shovel or fork the materials into the now-empty pen.
It’s convenient to set up the frame near, or even right inside, your vegetable garden. When the bin is full, you can move the frame to another convenient location and begin a new pile.
Wood and wire compost bin. Construct a portable bin using four sides made of 3- by 3-foot pieces of ½-inch hardware cloth fastened to two-by-fours. Use hinges and hooks and eyes on one side to make a door.
All living organisms need water, but too much moisture drives out air, drowns the pile, and washes away nutrients. A successfully functioning compost pile is about as damp as a moist sponge. There are several ways to control moisture levels in compost piles.
Build your pile on a site that is well drained. If necessary, start with a bottom layer of sand or gravel to make sure the pile never sits in a puddle.
Sprinkle each layer with a watering can or garden hose as you construct the pile. Or, after you build the pile, loop a soaker hose in rings over the pile surface and turn on a slow flow that will gradually moisten the pile. Check the moisture level every few days and, if necessary, add water when you turn your compost.
Mix very wet, sloppy materials such as fruit wastes with absorbent ingredients such as sawdust or shredded dry leaves.
If your pile seems too wet, use a garden fork or composting fork to fluff and turn the materials.
Protect your pile from the weather. Compost in a covered bin, or place a layer of hay or straw over your pile.
Shape your pile to work with weather conditions. In humid climates, build a pile with a rounded top, which tends to shed excess water. In dry climates, a sunken, or concave, top helps water soak into the pile.
Wire compost pen. A 10-foot length of 4-foot-wide welded wire fencing forms a circular compost pen slightly larger than 3 feet in diameter. Fasten the ends of the fencing together with wire or reusable clips. Use a bundle of sunflower stalks to direct moisture to the center of the pile.
Supplying enough air to all parts of a compost pile encourages thorough decomposition. Frequent turning is the most straightforward way to do this, but there are other aerating techniques to use in addition to or even in place of turning.
Build a base of coarse material such as brush or wood chips under your pile to allow air penetration from below.
Shred leaves, hay, and garden debris before composting. Use materials such as paper and grass clippings sparingly, because they tend to form impermeable mats when wet.
Insert sticks into the pile when building it, then pull them out later to open air passages. You can also poke holes in the compost with a garden fork or crowbar.
Bury perforated drainpipe at intervals in a passive compost pile as an excellent way to improve aeration. Sunflower stalks and straw also conduct air into compost; cornstalks don’t hollow out as they decay and won’t work for this purpose.
Limit both the height and width of the pile to 5 to 6 feet to avoid compression.
Conventional compost piles aren’t the only way to make great compost. You may want to experiment with composting right on top of your garden beds (sheet composting) or making compost in special bins with composting worms added (vermicomposting).
Nowhere is it written that gardeners must till, spade, and generally churn up more soil than an army of earthworms to have successful gardens. How do you garden without digging or cultivating? It’s easier than you might think. Simply start collecting all manner of organic wastes and spread them evenly over a garden bed, making sure that the base layer is a high-nitrogen material such as kitchen wastes. Moisten the whole thing, and top it with a few inches of a dry material like straw or shredded leaves to keep in the moisture. Earthworms will work their magic on the smorgasbord of organic materials that you’ve heaped on the soil surface. Note: If you have pet dogs, you’ll need to put a temporary fence around this bed, too, or they’ll probably dig right through the covering layer to search for goodies beneath.
You don’t need a lot of space to compost successfully. You can make a simple outdoor composter by cutting out the bottom of a trash can and setting the can firmly into the ground to prevent tipping. Use several such cans for continuous waste composting; simply wait 6 months to a year, depending on your climate, for the finished product. Chopping your wastes first speeds up the process, as does occasional turning or fluffing of the can’s contents. Air holes, drilled into the sides and lid, provide aeration to keep the system working and encourage earthworms to inhabit your garbage can composter.
Compost tumblers, also called barrel or drum composters, are available at most garden centers and from mail-order garden suppliers. These devices offer many of the benefits of hot composting while easing the effort of turning. Compost tumblers work quickly; used according to the manufacturer’s instructions, they produce finished compost in about 2 weeks. Their capacity tends to be limited, however; once the drum is full, you have to wait until composting is complete before adding new materials. Store kitchen wastes in plastic buckets with tight-fitting lids during this time, using sawdust or similarly absorbent materials to minimize odors. Also, it’s important to shred or chop all materials before adding them to the tumbler. The compost won’t “cook” unless everything in the tumbler is the right size and is kept moist.
Even apartment dwellers can make compost indoors with the help of earthworms. A worm box, with air holes, drainage, and a healthy earthworm population, helps turn food wastes into compost with very little effort on your part. As a rule of thumb, you’ ll need a container with 1 square foot of surface area for each pound of waste material added per week—a box 3 feet square and 1 foot deep can accommodate most of an average household’s food wastes. You can also use a plastic garbage can, modified to allow drainage and aeration, as a worm-powered indoor composter. Read the Earthworms entry to learn more about composting with earthworms.
Hot compost is generally ready to use in less than 8 weeks after you build the pile. Frequent turning is the secret: It keeps the compost well aerated so that decomposer organisms can work efficiently. Keep your compost working properly by monitoring the temperature and turning the pile as soon as the temperature drops. The object is to maintain elevated temperatures until decomposition is complete. A thermometer is helpful but not essential; you can stick your hand down into the pile to see how hot it is. Or insert a metal rod into your compost. If the rod feels hot to the touch after a few minutes in the pile, your compost is heating properly.
Temperature and critical mass: Too large a pile interferes with aeration, but a minimum size of 3 feet in each dimension is needed for optimal heating. Given the proper C/N ratio, moisture, and aeration, your compost will heat up even in cold winter weather. A hot pile can reach temperatures of 160°F but will produce satisfactory results if it cooks along at about 120°F. Northern gardeners sometimes insulate their piles with hay bales or leaves to help composting continue throughout winter.
Pros and cons: The main advantage of hot composting is its speed—even in cooler climates you can process six or more batches in a season. Thus, hot composting is a good way to generate a lot of compost quickly. Plus, the high temperatures in a hot compost pile will kill many weed seeds and pathogens. Practice your hot-composting skills, though, before you include diseased plants or seed-bearing weeds on your list of compost ingredients. Weeds such as Canada thistle that sprout readily from small pieces of root also are better left out of the compost bin.
The major disadvantage of hot composting is the labor involved in turning the compost every few days. It is also a less forgiving process than others: If the moisture level or C/N ratio is wrong, you have to make adjustments. Another drawback is that the whole pile must be built at once, so you’ll need to stockpile materials until you have enough to build a pile of the minimum size necessary.
Hot composting conserves less nitrogen than cooler methods because fast bacterial growth requires extra nitrogen, some of which inevitably drifts off in the form of ammonia. Finally, studies have shown that compost produced at high temperatures doesn’t suppress soilborne diseases as well as cool compost can, since hot composting also kills the beneficial bacteria and fungi that would attack such pathogens once the compost is added to garden soil.
Think twice before you add the following materials to a compost pile:
Lime and wood ashes. Adding lime to a compost pile can moderate pH and odors, but it’s not always a desirable addition. Lime can trigger the release of nitrogen into the atmosphere in the form of ammonia, particularly from piles that include manure. Instead, moderate pile pH by adding crushed eggshells, bonemeal, or wood ashes, which also provide potash. Like lime, wood ashes are alkaline and will raise the pH of your compost. Use wood ashes in moderation to avoid high pH levels because high pH conditions can inhibit microorganism activity and limit nutrient uptake by some plants.
Neighborhood yard wastes. Leaves and grass clippings from your neighbors’ yards are a great source of compost fodder, but not if your neighbors use chemical herbicides and pesticides—their yard wastes may contain harmful chemical residues.
Fats and meat scraps. It’s wise to keep fatty kitchen leftovers and meat scraps separate from the kitchen wastes you collect for composting. These materials break down very slowly, and their presence in a compost pile can attract undesirable animals, including rats.
Manure. Manure from cows, horses, chickens, rabbits, and other domestic livestock is fine for composting, as long as you handle it carefully. Manure may contain strains of E. coli bacteria that can cause serious—even life-threatening—illness, so always wear gloves when you’re working with it, and wash up thoroughly afterward. Make sure that compost made from manure is fully mature before you apply it to your garden.
Finished compost is a versatile material that you can apply freely at any time of year without fear of burning plants or polluting water. For most garden applications, use compost that is well finished—aged long enough so that the decomposition process has stabilized. Unfinished compost retards the germination and growth of certain plants, although others, such as corn and squash, seem to thrive on partly finished compost. Try these tips for using compost around your garden and yard.
Vegetables and annuals: Incorporate compost into the top inch or two of all annual beds (including your vegetable garden) before seeding or transplanting. Apply compost during the growing season as a mulch or side-dressing.
Trees and shrubs: If your soil is poor, avoid backfilling the planting hole with compost-enriched soil, since roots will tend to ball up inside the hole instead of branching out in search of nutrients. Instead, top-dress with compost over the entire root zone after planting.
Lawns: Spread compost when establishing new seedlings and rejuvenating your lawn in spring. Add fine compost when you aerate, so it comes in contact with roots.
Potting mixes: Compost provides an excellent medium for starting seeds and growing houseplants. Contrary to popular belief, pasteurization is unnecessary—heating compost actually suppresses disease-fighting microbes, allowing airborne pathogens to populate the growing medium. Simply screen your compost to remove large pieces and mix the fine compost with sand, peat moss, and other amendments to create a custom potting mix. (Use the large pieces you screen out as mulch or to “seed” a new compost pile.)
Compost tea is an effective, mild, natural fertilizer for seedlings and garden plants, and it can suppress fungal plant diseases. The tea-brewing process extracts, and in some cases grows and multiplies, nutrients and beneficial bacteria and fungi from compost and suspends them in water in a form that makes them quickly available to plants.
When you brew compost tea, be sure to use mature, sweet, earthy-smelling compost. Sour or unpleasant odors indicate anaerobic decomposition and mean that the compost contains few of the beneficial microbes you want in your “tea.” The best source of compost for tea making is a mature (3- to 8-month-old) pile. Keep in mind that harmful strains of E. coli can be present in the raw ingredients of a compost pile. Minimize the risk by maintaining a hot pile or allowing the compost to mature fully. And don’t apply compost tea to any vegetable within 3 weeks of its planned harvest date.
Making compost tea doesn’t require any special equipment. Here’s how to do it.
1.Fill a bucket with one part compost to five parts water, stir well, then let the mixture ferment—outdoors (the fragrance is strong!)—for 10 days to 2 weeks. Protect the brewing tea from extreme temperatures—it shouldn’t be in danger of freezing or in full sun that will cook all the good organisms in it.
2.After 10 to 14 days, strain the tea into another bucket, allow it to settle, and fill your sprayer with liquid from the top (without stirring up any of that bot tom sediment). Use cheesecloth, burlap, old nylons, or other fabric to strain out the solids, and return these to your compost pile.
3.Spray the tea without further dilution. This fermented recipe is particularly good for suppressing diseases and is a fine general-purpose foliar fertilizer. You can also use it to water seedlings and transplants.
4.Pour any sediment in the bottom of your sprayer back into the compost pile. Get another batch of tea brewing so it’s ready in 2 to 3 weeks for a follow-up application. Be sure to wash tea-sprayed produce before you eat it.
Municipal compost operations range from small, leaf-composting facilities to huge systems capable of turning 800 tons per day of waste into compost. Most facilities use windrows that are either turned every few days with mechanized compost turners or aerated using forced-air methods. A few are fully enclosed, automated “in-vessel” compost systems that take in refuse at one end and sort, grind, mix, moisten, and aerate it on its way to the other end of the process, where it arrives as finished compost.
Whether they are highly sophisticated or very simple, municipal compost programs’ primary interest is reducing the volume of materials going to landfills. While they also may produce high-quality compost, this is not their main goal, and savvy gardeners looking to use compost from the local facility would do well to learn what goes into the mix in their municipality and how the materials are handled and turned into compost.
Municipal compost facilities often make their product available to area residents at little or no cost. To locate nearby composting facilities, contact local governing bodies responsible for solid waste management; most states maintain listings of operating or planned compost facilities as well. The quality of compost produced by municipal operations can vary considerably, depending on the nature of the materials composted, the skill of the facility’s operators, and how long the product has been allowed to mature. Most states prohibit distribution of compost containing heavy metals or other toxic contaminants to the public.
It’s a good idea to test municipal compost for herbicide residues before you apply it to gardens or use it to make a potting mix. Simply sow seeds of sensitive crops such as cucumbers, tomatoes, or peas (make sure the seed is viable) in containers filled with compost. Watch the seedlings for several weeks. If the seedlings germinate poorly or are not properly formed, it’s a sign of a problem. You won’t know whether the cause is herbicide residue or simply poor-quality compost, but whatever the cause, you won’t want to use that compost in your garden.
See Echinacea; Rudbeckia
Larkspur. Spring- and summer-blooming annuals.
Description: Delphinium look-alikes, larkspurs are cool-weather annuals with feathery leaves and showy, spikelike clusters of spurred flowers in shades of rich blue, deep purple, lavender, pink, and white. Standard cultivars are 2 to 4 feet tall; dwarfs reach 1 to 2 feet. Plants bloom all summer in areas with cool summers; in spring and early summer where summers are hot.
How to grow: Since larkspurs resent transplanting, sow seeds outdoors where the plants are to grow in fall for bloom the following year or in spring beginning as soon as the soil can be worked. Sow new seeds every 3 to 4 weeks to extend the bloom season. You can also start seeds indoors in individual pots or purchase transplants and move them with care. Stake tall cultivars. Plants will self-sow, so leave some flowers in the garden to set seeds.
Landscape uses: Use larkspurs to fill in over spring-blooming bulbs and plant them in perennial gardens for added color. Tall cultivars make excellent cut flowers; be sure to include them in the cutting garden.
Pots, tubs, and half barrels overflowing with flowers add appeal to any garden, but container gardens can serve practical purposes, too. Gardening in containers is ideal for those with little or no garden space, and pots that raise plants up off the ground can make gardening accessible to people whose mobility is limited. In addition to growing flowers, gardeners tending a balcony, a small yard, or only a sunny patch on their driveway can produce a wide variety of vegetable crops in containers. Basil, chives, thyme, and other herbs also are quite happy growing in pots, which can be set in a convenient spot right outside the kitchen door.
Container plants add versatility to gardens large and small. They lend instant color, provide a focal point in the garden, or tie in the architecture of the house to the garden. Place them on the ground or raise them on pedestals, mount them on windowsills, or hang them from your porch. A pair of matching containers on either side of the front walk serves as a welcoming decoration, while containers on a deck or patio can add color and ambience to sitting areas. You can use single large containers for outdoor decoration, but also consider arranging groups of pots, both small and large, on stairways, terraces, or anywhere in the garden. Clusters of pots can contain a collection of favorite plants—succulents, such as hen and chicks (Sempervivum spp.), or herbs used both for ornament and for cooking, for example—or they may feature annuals, dwarf evergreens, perennials, or any other plants you’d like to try. Containers provide the perfect opportunity to experiment with new or unfamiliar plants, allowing you to “test grow” them for a season before you buy and plant a whole border full. Houseplants summering outdoors in the shade also make handsome additions to container gardens. Window boxes and hanging baskets offer even more ways to add instant color and appeal.
Containers planted with a single species—rosemary (Rosmarinus officinalis) or a bold variegated ornamental grass, for example—can be stunning garden accents. Containers planted with a mix of plants are fun to create and offer almost unlimited possibilities of combinations. The best combinations depend on plants that feature handsome foliage and flowers produced over a long bloom season. One easy guideline for choosing the plants to combine in a container is to include “a thriller, a spiller, and a filler.” That translates to at least one focal-point plant (the thriller), such as coleus or a geranium with multicolored leaves, for example, combined with several plants that spill over the edge of the pots—such as petunias, bacopa (Sutera cordata), creeping zinnia (Sanvitalia procumbens), or ornamental sweet potato (such as Ipomoea batatas ‘Blackie’). Finally, add the fillers, which are plants with smaller leaves and flowers that add color and fill in the arrangement all season long. Good fillers include salvias (Salvia spp.), verbenas (Verbena spp.), ornamental peppers (Capsicum spp.), and wax begonias (Begonia × semperflorens-cultorum) as well as foliage plants like parsley or licorice plant (Helichrysum petiolare). You may also want to include a plant for height, such as an ornamental grass like purple fountain grass (Pennisetum setaceum ‘Rubrum’). Add a trellis or pillar to a container and you can use a vine to add height to the composition. You’ll need a total of five or six plants for an 18- or 24-inch container, for example.
Pots and planters come in a wide range of sizes, shapes, materials, and styles. You can also modify everyday containers such as bowls or barrels to be planters.
Size: When choosing a container, keep in mind that it’s easier to grow plants in large containers than small ones. Large containers hold more soil, which stays moist longer and is less subject to rapid temperature fluctuations. Small hanging baskets are especially prone to drying out; during hot summer weather you may have to water them twice a day to keep plants alive.
It’s also important to decide what plant you want to grow in each container. Several factors help determine how large and deep the container must be. Consider the size and shape of a plant’s root system; whether it is a perennial, annual, or shrub; and how rapidly it grows. Rootbound plants, which have filled up every square inch of the soil available, dry out rapidly and won’t grow well. Choose a large pot or tub for a mixed planting, one that will offer enough root space for all the plants you want to grow. Light-colored containers keep the soil cooler than dark containers.
The maximum size (and weight) of a container is limited by how much room you have, what will support it, and whether you plan to move it. If your container garden is located on a balcony or deck, be sure to check how much weight the structure will safely hold.
Drainage: Whatever container you choose, drainage holes are essential. Without drainage, soil will become waterlogged and plants may die. The holes need not be large, but there must be enough so that excess water can drain out. If a container has no holes, try drilling some yourself. A container without holes is best used as a cachepot, or cover, to hide a plain pot. Cachepots (with holes and without them) are useful for managing large plants and heavy pots: Grow your plant in an ordinary nursery pot that fits inside a decorative cachepot so you can move them separately.
Self-watering, double-walled containers, hanging baskets, and window boxes are available. These are useful for dealing with smaller plants that need frequent watering.
Materials: Each type of container has merits and disadvantages.
Clay or terra-cotta containers are attractive but breakable and are easily damaged by freezing and thawing. In northern areas, most need to be stored in a frost-free location to prevent cracking and are not suitable for hardy perennials or shrubs that will remain outdoors year-round.
Cast concrete is long lasting and comes in a range of sizes and styles. These can be left outside in all weather. You can even make attractive ones yourself. Plain concrete containers are very heavy, so they are difficult to move and not suitable for using on decks or balconies. Concrete mixed with vermiculite or perlite, or concrete and fiberglass blends, are much lighter.
Plastic and fiberglass pots and planters are lightweight, relatively inexpensive, and available in many sizes and shapes. Choose sturdy and somewhat flexible containers and avoid thin, stiff ones—they become brittle with cold or age.
Containers made of polyurethane foam weigh up to 90 percent less than terra-cotta or concrete containers, yet they look remarkably like their much-heavier cousins. Polyurethane foam containers resist chipping and cracking and can insulate roots against both hot and cold temperatures, making them a good choice for holding plants that will stay outside year-round.
Wood is natural looking and protects roots from rapid temperature swings. If you’re reasonably handy, you can build wooden planters yourself. Choose a naturally rot-resistant wood such as cedar or locust, or use pine treated with a nontoxic preservative. (Don’t use creosote, which is toxic to plants.) Molded wood-fiber containers are sturdy and inexpensive.
Metals are strong, but they conduct heat, exposing roots to rapid temperature fluctuations. Exposure to moisture and fertilizers can cause corrosion and deterioration of metal containers. Some metals may leach compounds that make them undesirable for growing edible plants. If you crave the look of metal for your container garden, consider using metal containers as cachepots over more utilitarian containers.
Since containers are heavy once they are filled with moist soil, decide where they will be located and move them into position before filling and planting. If watering during the day poses a problem, look for sites that receive morning sun and are shaded during the hottest part of the day, even if you are growing plants for full sun. Afternoon shade will reduce the amount of moisture plants need.
While your containers must have drainage holes, the traditional practice of covering the holes with pot shards or gravel before you add potting mix is unnecessary. The covering doesn’t improve drainage, and pot shards may actually block the holes. Instead, prevent soil from washing out by placing a layer of paper towel or newspaper over the holes before adding mix. If your container is too deep, you can put a layer of gravel or Styrofoam in the bottom to reduce the amount of potting soil required.
Plain garden soil is too dense for container plantings. For containers up to 1 gallon in size, use a houseplant soil mixture; see the Houseplants entry for a recipe. For larger containers, use a relatively coarse soilless planting mixture to maintain the needed water and air balance. Buy a commercial container planting mix or make your own from equal parts of compost, pulverized pine or fir bark, and perlite or vermiculite. For each cubic foot of mix add 4 ounces of dolomitic limestone, 1 pound of rock phosphate or colloidal phosphate, 4 ounces of greensand, 1 pound of granite dust, and 2 ounces of bloodmeal.
Many of the components of potting soil are lightweight, dust-producing materials that can irritate your eyes, skin, and lungs. Vermiculite can contain low levels of asbestos; compost and peat moss may contain mold spores. When you work with potting soil and other soil, observe the following precautions.
Work outdoors or in a well-ventilated garage or garden shed.
Wear a dust mask.
Dampen individual ingredients before mixing them together to minimize the amount of dust in the air.
When you’re finished, wash your hands thoroughly. If you’ve been working with vermiculite, be aware that the dust can cling to your clothing. Remove and wash dusty clothing as soon as possible to avoid dispersing asbestos inside your house.
You may want to mix in one of the special superabsorbent polymers—synthetic substances that hold large amounts of water available for plants. They improve water availability without making the soil soggy. While these products are not naturally occurring substances, they appear to be inert and to have no toxic breakdown products.
Premoisten soil either by watering it before you fill containers or by flooding the containers with water several times and stirring. Be sure the soil is uniformly moist before planting. Peat moss, in particular, is difficult to moisten thoroughly once it’s in a container. Dampen your mix before filling your pots and before putting in plants. Keep peat-based mixes evenly moist after planting, as they are difficult to rewet if they dry out completely.
Plant in containers as you would in the garden. If you are planting a mixed container, ignore spacing requirements and plant densely; you will need to prune plants once they fill in. For trees and shrubs, trim off any circling roots and cover the rootball to the same level as it was set at the nursery. Firm the planter mixture gently and settle by watering thoroughly. Don’t fill pots level to the top with soil mixture—leave space for watering.
Almost any vegetable, flower, herb, shrub, or small tree can grow successfully in a container. Dwarf and compact cultivars are best, especially for smaller pots. Select plants to suit the climate and the amount of sun or shade the container will receive. If you are growing fragrant plants, such as heliotrope (Heliotropium arborescens), place containers in a site protected from breezes, which will disperse the perfume.
Use your imagination, and combine upright and trailing plants, edibles, and flowers for pleasing and colorful effects. Container gardens can be enjoyed for one season and discarded, or designed to last for years. When designing permanent containers, remember that the plants will be less hardy than usual because their roots are more exposed to fluctuating air temperature. Nonhardy plants will need to have winter protection or be moved to a sheltered space. Consider how heavy the container will be and how you will move it before choosing a plant that must be moved indoors for the winter.
Here are suggestions to get you started.
Vegetables and herbs. You can grow vegetables in individual containers—from large pots to 5-gallon buckets or half barrels, the largest of which will accommodate a single tomato plant or two or three smaller vegetables such as broccoli or cabbage. Dwarf or bush forms of larger vegetables such as tomatoes, pumpkins, and winter squash are best suited to container culture. Have fun with theme gardens. Plant a salad garden with colorful lettuces, dwarf tomatoes, chives, and parsley. Or perhaps try a pizza garden, with different types of basil, plus tomatoes and peppers. Or plant a container with edible flowers such as marigolds, pansies (Viola × wittrockiana), and nasturtiums (Tropaeolum majus).
Annuals. For containers that remain attractive all summer long, choose warm-weather annuals that bloom all summer or have foliage that remains attractive. Geraniums, marigolds, wax begonias, coleus (Plectranthus scutellarioides), scarlet sage (Salvia splendens), and flowering tobaccos (Nicotiana spp.) all are good choices, but you will find many, many more in garden centers and seed catalogs. Experiment, and if one plant doesn’t work out, don’t worry about it—just cut it down and try something else. For large containers, dwarf cannas and dwarf dahlias also make satisfying additions.
Perennials and shrubs. Containers planted with hardy perennials and shrubs can be grown and enjoyed from year to year. Hostas and daylilies (Hemerocallis spp.) are great container plants, but many other perennials work as well. Try ferns, European wild ginger (Asarum europaeum), sedges (Carex spp.), lavender, spotted dead nettle (Lamium maculatum), sedums, and lungworts (Pulmonaria spp.). Ornamental grasses are great in containers, too, as are dwarf conifers and small shrubs.
Water container plants thoroughly. How often depends on factors such as weather, plant size, and pot size. Don’t let soil in containers dry out completely, as it is hard to rewet. To keep large containers attractive, spread a layer of mulch on top of the potting mix, much as you would in the garden. This will also help retain moisture. Leave an inch or so of unmulched space around plant stems.
Container plants need regular feeding. Fertilize them by watering with diluted fish emulsion, seaweed extract, or compost tea. Or foliar feed by spraying the leaves with doubly diluted preparations of these solutions. Start by feeding once every 2 weeks; adjust the frequency depending on plant response.
Since containers are focal points in the garden, you will probably want to give them special attention to keep them looking their best. Remove tattered leaves and deadhead spent flowers. Prune back plants that get leggy or stop blooming. To keep mixed pots attractive, dig out or cut back any plants that don’t grow well or that clash. You can add something else or let other plants in the container fill the space. Keep an eye out for pests like aphids and mites; see the Pests entry for control guidelines.
Coreopsis, calliopsis, tickseed. Summer-blooming annuals; late-spring- to fall-blooming perennials.
Description: Coreopsis tinctoria, annual calliopsis, bears loads of single, 1- to 2-inch, broad-petaled daisies in shades of yellow, gold, red, brown, and combinations. The 1- to 2-foot erect plants are scantily clad in fine, threadlike leaves.
C. grandiflora, large-flowered tickseed, bears 2½-inch, deep yellow daisy flowers on 1- to 2-foot perennial plants; leaves may be lance-shaped or lobed. Zones 4–9.
C. lanceolata, lanceleaf coreopsis, bears single, semidouble, or double yellow daisies on 1- to 2-foot perennial plants; leaves are lance-shaped. Zones 4–9.
Perennial hybrid coreopsis—from C. grandiflora and C. lanceolata—bears single to double, 1½- to 3-inch, mostly gold daisies on long, leafless stems above loose sheaves of long, medium green leaves; some have red-ringed centers. Plants grow 10 to 36 inches tall. Zones 4–9.
C. rosea, pink tickseed, bears numerous 1-inch, pink daisy flowers on mounded 1- to 2-foot perennial plants with needlelike leaves. Zones 4–8.
C. verticillata, threadleaf coreopsis, produces many 1- to 2-inch, starlike blooms in yellow and gold shades atop 1- to 3-foot spreading mounds of delicate, airy foliage. C. verticillata ‘Moonbeam’, with pale yellow flowers, was named Perennial Plant of the Year for 1992 by the Perennial Plant Association. Zones 3–8.
How to grow: Sow annual calliopsis in spring (in fall in the South) where they are to bloom in a sunny, average to less fertile, well-drained spot. Although their bloom season is short, they tolerate heat and drought very well, and will self-sow freely for the next year or perhaps for a second crop in fall.
Give perennial coreopsis similar conditions, dividing them every few years in spring or fall. Taller hybrids need staking; prompt deadheading will prolong bloom throughout much of the growing season. Cut back threadleaf coreopsis after the main flush of bloom to encourage another heavy bloom in fall. Or let it continue to bloom unchecked, although it will bloom less spectacularly.
Landscape uses: All coreopsis are excellent plants for borders and cottage gardens. Taller coreopsis will also brighten meadow and prairie gardens. Hybrids provide plenty of cut flowers.
Zea mays
Poaceae
Historically speaking, corn is more American than apple pie: It’s been cultivated in North American gardens for more than 4,000 years. Even though it takes a large share of garden space, many gardeners make room for sweet corn because of the unbeatably sweet, distinctively corny flavor of fresh-picked ears.
The sugar in the kernels of ears of open-pollinated sweet corn varieties starts changing to starch almost as soon as you pick the ears. However, plant breeders have developed dozens of new and ever-sweeter cultivars that retain their sugar content for days. If sweetness is your prime goal, choose varieties listed as supersweet (abbreviated as sh2 in seed catalogs), but keep in mind that these may not be as vigorous as other types of sweet corn. If you prefer good old-fashioned corny flavor, pick standard (su) varieties. For a compromise of sweetness and vigor, choose sugary-enhanced varieties (se). Or, if you like to experiment with the latest innovations, try planting a synergistic variety (syn). These varieties produce ears with a combination of sugary-enhanced kernels and supersweet kernels on each ear. Whichever type you decide to grow, it’s a good idea to check with other local growers or your Cooperative Extension Service to see what varieties have a good track record in your area.
If you have lots of garden space, you may also want to try growing some popcorn or ornamental corn, which has similar planting and care needs as sweet corn. Don’t despair if your small growing space makes corn seem out of the question—dwarf varieties meant for container or raised-bed culture may be found from seed catalogs and online seed vendors. Ornamental corn cultivars—like other tall ornamental grasses—make attractive temporary screens or backdrops for a flowering border. A large container of growing corn provides a dramatic vertical accent on a patio and, if you’re willing to hand-pollinate, can yield a few ears for the table as well.
Planting: Corn is very susceptible to frosts. You can lose a crop if you plant too early. Corn doesn’t transplant well, either, so if you garden in a short-season area and want to start corn indoors, use biodegradable pots to avoid disturbing the roots at transplanting time. It’s better to wait until all danger of frost is past and the soil warms up to the 60°F needed for seed germination. If the weather stays cool, spread black plastic on the planting area to warm the soil more quickly.
If you want corn only for fresh eating, plant a minimum of 10 to 15 plants per person. To extend your harvest, sow an early-maturing type every 2 weeks for 6 weeks, or plant early, midseason, and late types at the same time. To avoid cross-pollination, keep different corn cultivars (especially supersweets) 400 or more yards apart, or plant them so they develop tassels 2 weeks apart.
Site your corn patch in a sunny, wind-protected area. Corn is a nitrogen-hungry crop, so it thrives in a place where soil-enriching crops like beans, hairy vetch, or clover grew the previous season. To prepare the soil to suit corn’s needs, add 20 to 30 pounds of compost per 100 square feet before planting.
The best way to promote complete pollination is to plant corn in blocks rather than long individual rows—a block should be at least three rows wide. If you plant only one or two rows, hand-pollinate to improve kernel formation, as described on the next page.
For early plantings, sow seeds only 1 inch deep; in the hot weather of midsummer, plant kernels up to 2 inches deep. The average germination rate for sweet corn is about 75 percent, so plant three seeds together every 7 to 15 inches. They should germinate in 7 to 10 days. Thin to one plant every 15 inches. To avoid disturbing remaining plants, remove unwanted seedlings by cutting them off at soil level.
Growing guidelines: Corn doesn’t compete well with weeds, so clear the area thoroughly before planting and cultivate around the young stalks for the first month of growth. After that, corn’s shallow roots will spread out as much as 1 foot from the stalk and are easily damaged by cultivation. Instead, apply mulch to prevent weeds from sprouting.
Corn needs about 1 inch of water a week, particularly when the stalks begin to tassel. Water stress during pollination will result in ears with lots of missing kernels, so don’t skip watering your corn patch. Apply water at the soil surface by using a soaker hose or drip irrigation. Avoid spraying plants from above, which could wash pollen off the flowering tops.
When the stalks are 6 inches tall, side-dress them with bloodmeal or diluted fish-based fertilizer, and repeat the feeding when they are about knee-high. Don’t remove any side shoots or suckers that appear; they won’t harm production, and cutting them might damage roots.
Problems: Cutworms sometimes attack corn seedlings, and flea beetles may chew holes in the leaves of young plants. You’ll find details on controlling these pests in The Top 10 Garden Insect Pests.
Corn earworms are one of the most common corn pests. They also attack tomatoes and are most prevalent in the southern and central states. Earworm moths lay eggs on corn silks, and the larvae crawl inside the husks to feed at the tips of the developing ears. The yellow-headed worms grow up to about 2 inches long and have yellow, green, or brown stripes on their bodies. To prevent earworm problems, use an eyedropper or spray bottle to apply a mixture of vegetable oil, Bt (Bacillus thuringiensis), water, and a few drops of dishwashing liquid to the tip of each ear several days after the silks emerge. Or you can try pinning a clothespin to the tip of each ear once the silks start to turn brown to prevent the worms from crawling through to the ear.
European corn borers are 1-inch-long, beige-colored caterpillars marked with tiny black dots. They feed on foliage, especial near the top of the stalk where the leaves emerge. They also bore into the developing ears. Bt and spinosad are effective controls if applied early, before the borers tunnel into the stalks. Corn borers overwinter as full-grown larvae in weed stems and old cornstalks. Pull up and destroy such winter refuges to break their life cycle.
Cucumber beetle larvae, also known as corn rootworms, feed on corn roots, causing plants to weaken and collapse. Adults are yellow beetles with black stripes or spots. To kill the rootworms, apply Heterorhabditis nematodes to the soil (for more information on these nematodes, turn to Microbial Products: Beneficial nematodes).
Seed-corn maggots attack kernels planted too deeply in cool soil. These yellowish white maggots are ¼ inch long, with pointed heads. If they attack, wait until warmer weather to plant another crop at a shallower level.
Animal pests can seriously reduce your corn yields. Birds may be a problem at both seeding and harvesting time, while raccoons are fond of the ripening ears. For information on discouraging these creatures, see the Animal Pests entry.
Clean garden practices, crop rotation, and planting resistant hybrids are the best defenses against most common corn diseases, including Stewart’s wilt, a bacterial disease that causes wilting and pale streaks on leaves.
Corn smut is a fungal disease that makes pale, shining, swollen galls that burst when mature and release powdery black spores. Cut off and dispose of galls before they open. If necessary, destroy affected plants to keep smut from spreading. It can remain viable in the soil for 5 to 7 years. The immature galls have a texture similar to mushrooms and are prized in Mexican cuisine for their trufflelike flavor.
Harvesting: Three weeks after corn silks appear, start checking ears for peak ripeness. Pull back part of the husk and pierce a kernel with your thumbnail. If a milky liquid spurts out, the ears are at prime ripeness—rush those ears to the table, refrigerator, or freezer. Ears on the same stalk usually ripen a few days apart. A completely dry silk or a yellow or faded-green sheath means the ear is past its prime.
Leave ornamental corn and popcorn on the stalks to dry until the first hard frost. If the weather is cloudy and wet, cut and stack stalks in a cool, dry place until the corn dries.
To produce kernels, wind must deposit pollen from the tassels (corn’s male flowers) onto each of the silks (pollen tubes) on the ears. Every unpollinated silk results in an undeveloped kernel. If you’re planting only a single or double row of corn plants, you can improve pollination by transferring pollen from tassels to silks yourself. Collect pollen as soon as the silks emerge from the ears and the tassels have a loose, open appearance. Wait for a morning when there’s no breeze, and shake the tassels over a dry bucket or other container to release the pollen. Collect pollen from several plants. Immediately transfer the pollen into a small paper bag and sprinkle the powdery material onto the silks of each ear in your corn patch. Repeat once or twice on subsequent days for best results.
See Centaurea
Dogwood. Single- or multiple-stemmed deciduous spring-flowering trees or shrubs; herbaceous groundcovers.
Description: The many plants in this genus share characteristic foliage and flowers. The simple, ovate leaves come to a point at the end, and paired veins extend lengthwise from the midrib toward the leaf tip. The flowers, noteworthy in many species, feature petal-like bracts that surround the small, true blossoms. Some dogwoods have showy, white or brightly colored bracts, while others bear less-noticeable leaflike bracts.
Cornus canadensis, bunchberry, is native to the woods of North America and grows best in cool regions. Give it shade and acid soil. This herbaceous groundcover grows to 9 inches and has greenish white bracted flowers in spring that resemble those of flowering dogwood. Red berries appear in fall. Zones 2–5.
C. florida, flowering dogwood, grows in the shade of other trees in the forests of the eastern United States. In the landscape, it reaches heights of 20 to 40 feet and has a graceful, layered branching habit. Heart-shaped white or pink bracts surround the true flowers in early spring. Red berries that are favored by many birds and leaf color in shades of burgundy, scarlet, orange, and yellow appear in fall. Choose your dogwood from a nursery offering cultivars for your region because heat, drought, and cold tolerance vary within the species. Zones 5–8.
C. kousa, Kousa dogwood, has a vase-shaped habit, layered branching, and a maximum height of about 20 feet in the landscape. The flowers appear in late spring and are surrounded by white, pointed bracts. Raspberry-like fruits are green through summer, coloring pink when the leaves turn reddish in fall. Shedding bark reveals patches of tan and cream. Zones 5–7.
C. sericea, red-osier dogwood, is a native North American shrub. Its habit is loose and broadly rounded. The red stem color intensifies during dormancy, becoming strongest in the weeks just prior to bud break. White flowers bloom in flattopped clusters; white berries contrast nicely with reddish fall foliage. Zones 2–7.
How to grow: Dogwoods usually require partial shade, although some tolerate full sun in cooler climates. Provide evenly moist, humus-rich soil, good drainage, and mulch to shade the roots. (Swamp dwellers like red-osier dogwood tolerate some standing water.) Dogwoods have little tolerance for air pollution, reflected heat, and other urban conditions. Insects and diseases that afflict dogwoods include dogwood borer, anthracnose, and stem canker. To counteract them, provide an appropriate planting site and minimize environmental stresses on the tree; for example, water during dry spells and protect trunks and stems from being damaged by enemies such as lawn mowers.
Although common across the eastern states, flowering dogwoods grown as specimens rarely prosper in full sun in the middle of lawns. Flowering is abundant for a few years, but soon you see dead wood, sucker shoots at the tree’s base, and unthrifty growth. If decline doesn’t finish off such trees, borers will. However, solitary trees do seem less likely to suffer anthracnose, a fungal disease that causes patches of dead tissue in the leaves, prospers in warm, wet weather, and is transmitted by splashing rain. Full sun and good air circulation around single trees limit anthracnose’s spread.
Landscape uses: Plant dogwoods for wildlife food in woodland gardens. Shrubby dogwoods are appropriate for grouping and screening. Use the red- or yellow-twigged shrubs where they can be seen on snowy days. Tree dogwoods make nice focal points but work better (visually and culturally) in groups. Try Kousa dogwood—or new hybrids between Kousa and flowering dogwoods—as a replacement for flowering dogwood, especially in sunny, dry locations.
Cosmos. Midsummer- to fall-blooming annuals.
Description: Cosmos bipinnatus bears 2- to 4-inch broad-petaled, daisylike flowers in shades of pink, red, and white, on mounds of light green, feathery foliage up to 5 feet. C. sulphureus has 2-inch orange, red, or yellow flowers and fernlike, dark green leaves on plants up to 3 feet.
How to grow: Direct-sow cosmos after danger of spring frost, in full sun in loose, average, well-drained soil. If necessary, transplant only when very small. Cut fading flowers for more blooms. Tall cultivars may need staking.
Landscape uses: Mass the tall cultivars by themselves or at the back of a border; use shorter cultivars in midborder clumps. Cosmos also make excellent cut flowers.
Cotoneaster. Deciduous or evergreen spring-blooming shrubs or groundcovers.
Description: Cotoneaster apiculatus, cranberry cotoneaster, is a low (to 20 inches), spreading groundcover with round, deep green, glossy leaves. Small pink flowers appear in spring, followed by red cranberry-like fruits. Fall foliage turns reddish before it drops. Zones 5–7.
C. divaricatus, spreading cotoneaster, eventually grows wider than tall, with a mature height of about 5 feet. Its purplish stems bear glossy oval leaves and pale pink spring flowers. Red berries appear in fall, accompanied by red foliage in most situations. Zones 5–8.
C. horizontalis, rockspray cotoneaster, is a spreading, mounding, layered plant with a functional height of 2 to 3 feet and a wider spread. It bears glossy green, rounded foliage that occasionally turns red before falling, revealing a herringbone branching structure. Zones 5–8.
C. multiflorus, many-flowered cotoneaster, is a deciduous shrub that attains a mature height of 8 to 12 feet. The broadly oval foliage is dull rather than glossy, with little fall color. This cotoneaster is known for its abundance of small white flowers in spring. Bright red berries are borne in fall. Zones 4–6.
C. salicifolius, willowleaf cotoneaster, grows to a height of 8 to 12 feet. Its gracefully arching branches bear slender, glossy, leathery leaves that usually persist through winter and may blush to a handsome red if the weather turns unusually cold. Small white flowers, largely hidden by the foliage in spring, are followed by slightly more visible red berries in autumn. Zones 6–8.
Note that in spite of appearances, cotoneaster is pronounced “kuh-tow-nee-AS-ter.”
How to grow: Cotoneasters thrive in a variety of soils, and most can tolerate wind exposure. Provide full sun and good drainage. North of Zone 8, plant in spring and fall; in Zone 8, plant in fall or winter. Once established, most cotoneasters will thrive without additional watering. Fire blight is a major concern and severely limits the use of these plants in the South. This disease causes new shoots to wilt suddenly, turn dark, and die back. It eventually spreads, killing the whole plant. Lush new growth is particularly susceptible, so avoid overfertilizing.
Landscape uses: Because of their spreading habit, cotoneasters are ideal as groundcovers, borders, barriers, screens, and massed plantings. They’re also good in mixed borders and foundation plantings. Rockspray cotoneaster makes an effective espalier.
Cottage gardening originated during the Middle Ages, when most people lived in very small houses—cottages—with even smaller plots of land around their homes. Unless you were a lord or a member of the landed gentry, there just wasn’t room for separate flowerbeds, herb gardens, vegetable gardens, and the like. Instead, people grew a patchwork of herbs, flowers, vegetables, and fruit trees outside their front door. These cheerful gardens can still be found along the lanes of English villages.
A focus on thrifty gardening was also characteristic of cottage gardens, since people didn’t have money to spend on ornamental plants and there weren’t any nurseries or garden centers. Seeds, cuttings, and transplants were passed along and cherished, and the hardier the plant, the more popular it was. Thus, plants that self-sowed and were easy to grow became cottage-garden staples.
Even if you don’t live in a cottage, you might enjoy a colorful, informal, low-maintenance cottage garden. Today, we tend to think of cottage gardens as flower gardens, perhaps with some ornamental herbs, a flowering shrub or two, and some roses spilling over a wooden fence. (For gardens that combine flowers with vegetables, fruits, and herbs, see the Kitchen Gardens entry.) Site your cottage garden in full sun, on both sides of the path to the front or back door, and enclose the garden with a rustic fence. A decorative gate or arbor at the garden’s entrance can add a charming touch. A cottage-style garden would also look lovely surrounding a toolshed or other outbuilding.
Traditionally, the path leading through a cottage garden proceeded in a straight line from the lane to the door—its purpose was functional, not decorative. However, you might prefer to make a meandering path through your garden. Cover the path with bark chips, old paving bricks, or cobblestones. Or create a fragrant path with stepping-stones nestled among low-growing, scented “path herbs” such as Roman chamomile (Chamaemelum nobile), woolly thyme (Thymus pseudolanuginosus), or Corsican mint (Mentha requienii).
The delightful informality of a cottage garden makes it a perfect place for accessories. A swing or bench is at home there, and so is a sundial, beehive, wind chime, gazing ball, or other ornament. Add a birdbath to welcome the many birds and butterflies that will visit your profusion of flowers, or place a rustic birdhouse on a pole. Remember not to overload your cottage garden with ornaments, though—the emphasis should always be on the flowers.
These cheerful flowers will give your cottage garden a joyful, exuberant look. The annuals self-sow freely, returning to your garden each year. And many of these spreading perennials have adorned cottage gardens for hundreds of years. Cottage-garden plants aren’t fussy; most prefer full sun and average soil.
Annuals
Browallia spp. (browallias, sapphire flowers)
Calendula officinalis (calendula, pot marigold)
Centaurea cyanus (cornflower)
Cleome hassleriana (cleome, spider flower)
Consolida ajacis (rocket larkspur)
Cosmos bipinnatus (cosmos)
Ipomoea spp. (morning glories)
Lobularia maritima (sweet alyssum)
Lunaria annua (honesty)
Mirabilis jalapa (four-o’clock)
Myosotis sylvatica (woodland forget-me-not)
Nemophila menziesii (baby-blue-eyes)
Nigella damascena (love-in-a-mist)
Papaver rhoeas (corn poppy, Shirley poppy)
Viola tricolor (Johnny-jump-up)
Perennials
Achillea filipendulina (fernleaf yarrow)
Achillea millefolium (common yarrow)
Achillea ptarmica (sneezewort)
Alchemilla mollis (lady’s mantle)
Anchusa azurea (Italian bugloss)
Artemisia ludoviciana ‘Silver King’ (‘Silver King’ artemisia)
Coreopsis verticillata (threadleaf coreopsis)
Delphinium spp. (delphiniums)
Digitalis spp. (foxgloves)
Echinacea purpurea (purple coneflower)
Hemerocallis spp. (daylilies)
Iris hybrids (bearded iris)
Lathyrus latifolius (perennial pea)
Lavandula spp. (lavenders)
Leucanthemum × superbum (Shasta daisy)
Lychnis coronaria (rose campion)
Monarda didyma (bee balm, monarda)
Oenothera fruticosa (narrowleaf evening primrose)
Oenothera speciosa (showy evening primrose)
Phlox subulata (moss phlox, moss pink)
Rudbeckia spp. (coneflowers)
Tanacetum parthenium (feverfew)
Viola odorata (sweet violet)
Viola sororia (woolly blue violet)
If you have room, consider a small flowering tree or two along the fence for year-round structure—perhaps a crabapple, dogwood, or dwarf fruit tree. Old-fashioned fragrant flowering shrubs such as lilacs (Syringa spp.), sweet mock oranges (Philadelphus coronarius), and shrub roses in the corners add structure and enhance the garden’s homey feeling. And don’t forget a rose of Sharon (Hibiscus syriacus) for the hummingbirds!
Choose flowers that fit the casualness of the cottage-garden style, like self-sowing annuals and spreading perennials. Fragrance and color are the hallmarks of cottage-garden flowers. You can mix ornamental herbs like anise hyssop (Agastache foeniculum), rosemary, and lavender with your flowers. Pineapple sage (Salvia elegans) and other fruit-scented sages, as well as many other species of ornamental salvia, are tender perennials but are worth growing as annuals north of their hardiness limits because their colorful flower spikes are hummingbird and butterfly magnets. If you have a greenhouse, sunroom, or sunny porch, you can set out pots of these plants in your cottage garden and bring them inside for winter.
To complete the effect, drape climbing roses, ‘Gold Flame’ honeysuckle (Lonicera × heckrottii ‘Gold Flame’) or Jackman clematis (Clematis ‘Jackmanii’) over a fence or arbor. Use fragrant favorites like violas, pansies, or sweet alyssum as edging plants along the walk.
Because part of its charm comes from its informal design, a cottage garden requires less work to maintain than more manicured gardens. But weeding can be a challenge in spring, when you have to decide which are self-sown annual, perennial, and herb seedlings and which are weeds. Thin or transplant flower seedlings as needed.
Add a top-dressing of compost and mulch each year after seedlings are well established. Pick off spent flowers of annuals early in the season to encourage more blooms, but allow flowers to ripen into seed heads or pods in late summer so they can disperse seeds to fill next year’s garden.
Sown to build the soil, to prevent erosion, to block weeds, or to serve as mulch for other plants, cover crops provide many benefits in the garden. Incorporating cover crops into the soil increases organic matter content, improves tilth, and supports healthy populations of earthworms and other desirable soil organisms. Gardeners who lack access to—or choose to not use—animal manures, or whose supply of compost falls short of their garden’s needs, can include cover crops, also called green manures, in their planting plans for garden areas that are replanted annually, such as vegetable or annual flowerbeds.
There are lots of great ways and great reasons to include cover crops in your gardening routine.
Plant a cover crop such as buckwheat or clover in fall, after finishing the harvest and clearing debris from the beds.
Sow a fast-growing cover crop such as oats or red clover in spring in areas where you plan to plant warm-weather crops like peppers. Let the cover crop grow for several weeks, then turn it under a few weeks before it’s time to plant the peppers.
Include cover crops in your a crop rotation scheme to disrupt pests and diseases.
When planning a new garden bed of any kind—for food crops or ornamentals—it’s a great idea to plant the area in a cover crop for part or all of a growing season to build the soil.
Use a cover crop to help bring tough weed problems under control (for more about this use of cover crops, see the Weeds entry).
The chart Cover Crops for Home Gardens will help you choose the cover crops that are best suited to your garden. If you select a legume, plan to apply bacterial inoculant so your soil will get maximum benefit from the crop’s nitrogen-collecting ability. Different legume crops require different strains of inoculant. Use the specific strain required by the legume you’re planting or a product that’s a blend of many types of nitrogen-collecting bacteria. You’ll find inoculants at well-stocked garden centers, or order them from online garden supply retailers.
Prepare the bed for planting as you would for any seed-sown crop. Remove all weeds and plant residues and rake the soil free of clumps before sowing. If possible, sow seed when rain is in the forecast. The seedlings will not establish well if the soil surface dries during the germination period. You can sow seed with a manually powered mechanical seeder that consists of a seed reservoir attached to a crank-operated seed broadcaster. For small areas, though, it’s easy to broadcast seed by hand. If you’re sowing less than 1 pound of seed per 1,000 square feet, mix the seed with fine sand or screened soil before spreading. Cover larger-seeded crops, such as Austrian peas or soybeans, with ¼ to ½ inch of soil; there’s no need to cover small-seeded crops.
After seeding, tamp the soil with the back of a hoe or spade to ensure good contact between soil and seed and water thoroughly but gently to avoid washing away the seeds. You can cover the newly seeded area with loose straw or grass clippings to help prevent drying. Keep the seedbed evenly moist until the seeds have germinated. For large plots (1 acre or more), a small seed drill pulled by a farm or garden tractor will plant and cover the seed in one pass.
Some gardeners sow a crop such as alsike or white clover between rows of young squash or corn plants where it acts as a living mulch—it’s a growing crop, but it serves all the functions of a standard mulch while also adding nitrogen to the soil. You can plant living mulches between many vegetable row crops.
This system works well only if you seed the living mulch in a weed-free seedbed. After planting the main crop, keep all areas between the rows and between individual plants clear of weeds for about 1 month. Cultivate lightly just before planting the mulch crop and pick out any exposed weed roots to prevent them from reestablishing. Work carefully to avoid disturbing the root systems of your vegetable plants. The annual cover crop will die down at frost or can be dug in when you prepare the soil for winter cover.
Late-season plantings of broccoli and cauliflower can benefit from undersowing with a winter-hardy cover crop such as hairy vetch. To undersow, let the vegetable crop get established for about 1 month, keeping the area weed-free. When the vegetable plants are 6 to 8 inches tall, broadcast the green manure seed over the entire area, not just between the rows. The vetch will germinate and grow, covering the soil without interfering with the vegetable crop. Harvest the crop in fall, and leave the vetch in place to protect the soil over winter. The following spring, cut off the vetch topgrowth close to the soil surface. The cut stems will die and dry out, forming a weed-suppressing mat. You can simply push aside the mulch mat as needed to plant transplants.
Oats are also effective as an undersown, or living mulch, crop. Planted anytime from the middle to the end of summer, the crop will suppress weeds but won’t set seed itself. The oats will die down during winter, leaving a thick layer of mulch to prevent soil erosion and suppress late-fall and early-spring weeds. Shallowly till or dig in the oats 2 weeks before planting the following spring. Or to conserve time and effort, hand-pull the mulch back in spots and transplant established seedlings into it. It will retard weed growth until it decomposes, by which time the plant’s leaves will be shading the area.
In general, you’ll need to cut down or dig in cover crops 3 to 4 weeks before you replant the bed. The old-fashioned way to turn in a cover crop was to use a rotary tiller, but that undoes some of the soil-building benefit that the cover crop supplies. Instead, try one of these options.
Bury the cover crop under a heavy layer of mulch, such as chopped leaves, to kill it. Then use a hand tool to lightly work the killed tops into the soil.
Pull up the crop by its roots and lay it on the bed surface as mulch.
Cut off the crop at ground level as soon as flowers form. Leave the cut material in place.
If you keep chickens, turn them loose on the plot to turn under the cover crop.
Keep in mind that, in general, it’s more work to incorporate a perennial cover crop than an annual one.
Cover crops vary in the benefits they provide your garden. For example, nonlegumes such as Sudan grass and winter rye add lots of biomass and improve soil structure because of their extensive root systems, while legumes such as clover add nitrogen that helps break down all that plant matter. Thus, planting a mix of a grass and a legume can be an especially good strategy.
| CROP | WHEN TO SOW | RATE PER 100 SQ FT | CULTURAL REQUIREMENTS | COMMENTS |
| LEGUMES | ||||
| Alfalfa (Medicago sativa) | Spring | 1.5 oz. | needs good drainage and pH higher than 6.5 | Significant nitrogen contribution. Perennial. |
| Alsike clover (Trifolium hybridum) | Spring or late summer | 1.5 oz. | Tolerates poor drainage and acid soils. | Low-growing perennial. |
| Austrian winter pea (Pisum sativum var. arvense) | Late summer or fall | 3–6 oz. | Prefers welldrained soils. | Winter legume for warmer climates. Annual. |
| Crimson clover (Trifolium incarnatum) | Spring or fall | 1–1.5 oz. | Likes neutral, well-drained soils. | Tall clover with dense root system. Annual. |
| Hairy vetch (Vicia villosa) | Late summer or fall | 1.5 oz. | Tolerates moderate drainage. Winter cover with rye. | Good nitrogen capture; grows well in northern climates. Annual. |
| Red clover (Trifolium pratense) | Spring or late summer | 1 oz. | Somewhat tolerant of acidity and poor drainage. | Good phosphorus accumulation; grows quickly for incorporating during same season. Biennial. |
| Soybean (Glycine max) | Spring or summer | 6 oz. | Tolerates poor drainage. | Inoculate for nitrogen fixation. Annual. |
| White (Dutch) clover (Trifolium repens) | Spring or late summer | 0.5–1 oz. | Tolerates droughty soils. | Good for under-sowing as a living mulch. Perennial. |
| Yellow sweet clover (Melilotus officinalis) | Spring or summer | 1–1.5 oz. | Intolerant of acid soils and poor drainage. | Root mass accumulates phosphate from rock powders. Biennial. |
| NONLEGUMES | ||||
| Annual ryegrass (Lolium multiflorum) | Spring | 1.5–2 oz. | Tolerates a wide range of soils. | Provides fast cover; good for establishing slow-growing crops. Annual. |
| Buckwheat (Fagopyrum esculentum) | Spring or summer | 3–5 oz. | Tolerates infertile and acid soils. | Accumulates phosphorus. Annual. |
| Oat (Avena sativa) | Spring or summer | 4–6.5 oz. | Prefers well-drained loamy soil. Tolerates some acidity. | Quick-growing summer crop. Quick cover for helping establish clover. Annual. |
| Rape (Brassica napus) | Spring or summer | 0.5 oz. | Prefers moderately well-drained loam. | Good cover for short growing periods in summer. Annual. |
| Sudangrass (Sorghum ×drummondii) | Spring or summer | 1.5–3 oz. | Will tolerate somewhat poorly drained soils. | Produces very large mass of root growth and top-growth in summer. Annual. |
| Winter rye (Secale cereale) | Spring or summer | 5–10 oz. | Prefers well-drained soil. | Very winter hardy, grows well in early spring. Annual. |
See Malus
Crocus. Spring- or fall-blooming corms.
Description: Crocuses bear nearly stemless, 1- to 2-inch-wide starry goblets in white, cream, yellow, gold, and purple, many marked or brushed with a contrasting color. Grassy leaves, usually quite short when in bloom, elongate to 4 to 6 inches. The familiar spring-blooming Dutch hybrid crocuses produce relatively large blooms in white, yellow, and purple shades, plus purple stripes on white, to 6 inches tall. Zones 3–9.
Species crocuses include early spring-blooming Crocus chrysanthus, golden crocus, which grows to 6 inches. Zones 4–9. Fall-blooming C. speciosus, showy crocus, bears lavender-blue flowers and can reach 6 inches or more. Zones 5–9.
How to grow: Plant crocus corms in fall at a depth two to three times their width in a sunny or partially shaded spot with average, well-drained soil enriched with organic matter. Plant fall-blooming crocuses as soon as they are available in mid- to late summer. Do not remove leaves until they have yellowed, when you can also lift and divide the corms. Rodents may eat the corms unless a resident dog or cat keeps them at bay. Slugs sometimes devour the flowers of fall-blooming species.
Landscape uses: Grow massed in thin grass (do not mow until the foliage has died back after blooming ends), in rock gardens, or in clumps along a path or at a doorstep. In borders, overplant with low-growing annuals like sweet alyssum so you won’t disturb them later in the season. Grow fall-blooming species in low groundcovers such as vinca (common periwinkle) to help support the flower stems.
Crop rotation is a systematic approach to deciding which crop to plant where in your vegetable garden from one growing season to the next. Crop rotation is very important to organic farmers, and it can benefit home gardeners, too. The general principles of crop rotation offer guidance for developing a planting plan, but it’s up to individual farmers and gardeners to devise a unique crop rotation based on their chosen crops, the space that’s available, and the objectives they hope to achieve.
The goals of crop rotation are to help manage soil fertility, to help avoid or reduce problems with soilborne diseases, and to disrupt the lifecycles of (and thus the damage caused by) soil-dwelling insects such as corn rootworms.
Balancing soil fertility: Each crop has unique nutrient requirements and draws specific nutrients from the soil where it grows. Some, like corn and tomatoes, are known as heavy feeders that require substantial amounts of soil nitrogen and phosphorus. If you plant corn in the same spot year after year, the nitrogen and phosphorus in that plot will be depleted more quickly than in other parts of your garden. Changing the location of corn each year allows you to replenish those nutrients in that part of the garden, so it’s ready when the next hungry crop comes along.
Other crops also demand lots of nitrogen. These tend to be the green and leafy crops, such as lettuce, cabbage, and broccoli. Fruiting crops, such as tomatoes and melons, require abundant phosphorus. Peas, beans, and other legumes add nitrogen to the soil but also need lots of phosphorus. By comparison, most root vegetables and herbs are light feeders, with relatively modest fertility requirements.
Susceptibility to pests and diseases runs in plant families. Leave at least 2, and preferably 3 or more, years between the times you plant members of the same crop family in an area of your garden. When planning a rotation scheme, refer to this list of the eight family groups most often planted in vegetable gardens along with suggestions for their order in a successful rotation plan.
The rule of thumb for balancing soil nutrients through rotation is to avoid planting the same general category of crop (root, legume, leafy, or fruiting) successively in the same place. It’s best to follow nitrogen-fixing legumes such as peas or beans with nitrogen-loving leaf crops or nutrient-hungry fruiting crops. Then, follow the heavy feeding crops with light-feeding root crops.
Disease and pest prevention: If you have a large home garden, you may want to base your crop rotation on plant families rather than on nutrient needs. This can help diminish diseases and pests, because closely related crops tend to suffer from the same problems. For example, Colorado potato beetles like to eat potato plants, but they also enjoy feasting on tomato leaves and eggplant foliage. Since these beetles overwinter in the soil, if you plant eggplant in a spot where you grew potatoes the year before, you may have a beetle problem for your eggplants from the day they’re planted. Likewise, several serious bacterial and fungal diseases overwinter in plant debris in the soil.
Lengthy rotations are sometimes necessary to control chronic soilborne problems. Bean anthracnose fungus can persist in soil for up to 3 years, so a 4-year rotation is needed to keep the disease at bay. The same holds true for such fungal diseases as fusarium wilt and verticillium wilt. A few problems, such as clubroot, persist in the soil for even longer, so rotation is less useful for controlling them.
Choosing your crop rotation plan: If you have a small garden, you may not be able to set up an effective rotation by crop family. That’s also true if you grow only a few kinds of crops. In that case, stick to a basic soil-balancing rotation. But if you have a large plot and grow many different crops, you may enjoy the challenge of setting up a rotation by crop family. Refer to the chart to learn which crops belong to the same family.
Keep in mind that cover crops can be included in a rotation plan to discourage specific types of pests and to improve soil. For example, beetle grubs thrive among most vegetables, but not in soil planted in buckwheat or clover. A season of either crop can greatly reduce grub populations and at the same time will increase soil organic matter content.
Cucumis sativus
Cucurbitaceae
Cool and juicy cucumbers are popular for both eating fresh and preserving as pickles. These frost-sensitive tropical natives like warm, humid weather and need at least 8 hours of sun a day. But since they require only 55 to 60 days from planting to picking, cucumbers will grow well in most regions as long as they get enough natural rainfall or supplemental water.
Types: Cucumbers range from petite gherkins and blocky picklers to torpedo-like market varieties, small lemon-shaped heirlooms, and long, thin, Asian types; there are also seedless and disease-resistant cultivars. Middle Eastern, or gourmet, cucumbers require no peeling—a nutritious advantage, since most of this vegetable’s vitamin A and C content, along with a number of minerals, is in the skin.
Bush cultivars produce compact vines that require less space in the garden. For high yields, try a gynoecious cultivar; instead of the usual male and female flowers, these plants produce only female blooms and, thus, more cucumbers. Cultivars labeled as parthenocarpic are able to set fruits without pollination, making them a good choice for growing under cover.
In seed catalogs, cucumbers are often divided into slicing types, used for salads or cooking, and smaller, fast-growing pickling kinds. Sometimes a cultivar is labeled “dual-purpose,” meaning that you can harvest them small for pickling or larger for slicing.
Planting: Cucumber yields are highest in fertile, clay soil with plenty of humus, but they will grow well in most good vegetable garden soils. Good drainage is essential.
The biggest mistake most gardeners make is planting cucumbers too early. It’s best to wait until the soil temperature reaches 70°F—at least 1 week after the date of the last frost. Spreading black plastic over the planting area will promote the soil warmth cucumbers need.
When you start seeds indoors, keep the air temperature between 70° and 80°F during the day and no colder than 60°F at night. Use peat pots instead of flats to avoid disturbing the cucumber roots during transplanting. Sow three or four seeds ½ inch deep in each pot, about 2 weeks before the last frost. When two or three true leaves have developed, snip off (don’t pull) all but the most vigorous seedling. Harden off the plants before transplanting by putting them outdoors during the day and bringing them in at night.
Plant up to three vines of each variety you want to grow. Rather than planting all your cucumbers at once, plan to stagger plantings a couple of weeks apart to extend the harvest (just make sure the fruits will have time to mature before fall frost).
You can grow cucumbers either in hills or in rows next to a fence or trellis. Make hills 2 feet wide; space hills or rows 4 to 5 feet apart (3 feet apart for bush cultivars). In each hill, place three transplants or sow seven or eight seeds; thin to the best three seedlings when they are a few inches tall by cutting the unwanted ones at ground level. If you’re planting in rows, plant seedlings 1 foot apart, or sow seeds 1 inch deep with three to five seeds per foot of row and thin seedlings to 1 foot apart.
If you’re growing gynoecious cultivars, remember to plant a few of the specially marked male seeds. Mark the male seedlings with a stake or flag to ensure you don’t thin them by mistake. Plants from these seeds will bear male flowers, which provide the pollen necessary for fertilization. One or two male plants will provide enough pollen for all the female flowers.
To make good use of garden space, consider interplanting cole crops, such as early cabbage, cauliflower, or broccoli, with your cucumbers; they should be ready to harvest around the time the cucumber seedlings come up. Radishes, bush beans, and lettuce are other good choices for inter-cropping with cukes. Just plan ahead when planting the early crops so that you leave enough space to plant the cucumber seeds or plants around them.
A-frame trellis. Training cucumbers on a stakes-and-string trellis saves garden space, keeps fruits up off the ground, and allows for good air circulation, which helps prevent disease problems.
Growing guidelines: Cucumbers are 95 percent water, so adequate moisture is vital to a good cucumber crop. A thirsty plant simply stops growing, and its fruits are likely to be deformed, bitter, or flavorless. Soak the soil deeply when watering in dry weather. Soaker hoses along rows are good for this purpose. Or punch a few very small holes in a coffee can, plastic jug, or soda bottle, and sink the bottom of the container into the middle of each hill. Keep it filled with water to maintain the even moisture the plants need. Avoid handling or brushing up against foliage when it’s wet to prevent the spread of diseases. Weed by hand until the seedlings are 1 foot tall; then side-dress with alfalfa meal or compost, water well, and lay down at least 2 inches of an organic mulch, such as straw, hay, grass clippings, or leaves. In addition to conserving moisture and suppressing weeds, the mulch will help keep fruits clean and healthy.
Male flowers appear first, followed by female blooms about a week later. Bees will spread the pollen from one to the other. If long periods of cloudy, rainy weather keep the bees inactive, you can do the job yourself by carefully picking a male flower and—after removing the petals—brushing its pollen-covered anthers against the stigmas in the center of the female blossoms. (See the Squash entry for an illustration of this technique.) Unpollinated blooms will produce tiny, curled, seedless cucumbers.
Problems: Cucumber beetles are a widespread and potentially serious pest. They not only chew on plants, particularly young seedlings, but also spread diseases such as bacterial wilt and mosaic. Adult cucumber beetles are ¼ inch long with black heads and greenish yellow wings; they chew large ragged holes in plant leaves. There are two species: the spotted cucumber beetle and the striped cucumber beetle. As many as three generations of beetles occur in a single growing season. Here’s how to battle them.
Inspect the foliage and insides of flowers daily, particularly in the early morning; handpick and destroy any beetles you find by shaking them into a jar of soapy water.
Lure striped cucumber beetles away from your cucumbers by planting radishes nearby.
Plant later in the season after the first round of beetles has finished feeding and laying eggs.
Cover young plants with a fine netting, such as cheesecloth, or with a floating row cover. Remember that a cover will also keep bees out; if you leave the cover on after flowering begins, you’ll have to hand-pollinate the flowers to get a crop.
Apply a coating of kaolin clay to the foliage, including leaf undersides, twice a week to deter the beetles from feeding. Reapply after heavy rain.
Drench the soil around your plants with Heterorhabditis nematodes to kill cucumber beetle larvae and thus prevent damage by second-generation beetles.
As a last resort, apply pyrethrins to control large infestations quickly.
Squash vine borers are 1-inch-long white caterpillars that burrow into the plants’ main stems, leaving sawdustlike droppings at their entry holes and causing the vines to wilt. At the first sign of this pest, cut a slit along the stem of the affected plant, remove and destroy the larvae, and cover the injured area and several close-by vine joints with moist soil. This enables the plant to put out new roots to help it recover. You can also attack the borers by injecting the stems with Btk (Bacillus thuringiensis var. kurstaki).
Handpick green melon worms that feed on foliage and occasionally munch their way inside a fruit. Handpicking and keeping the garden clean will also help control young pickleworms, pale yellow caterpillars with black spots that turn green- or copper-colored as they grow.
Other cucumber pests include cutworms, aphids, and spider mites. For information on controlling cutworms and aphids, see The Top 10 Garden Insect Pests. Spider mites are tiny creatures that feed on the underside of leaves, causing yellow stippling on leaf surfaces; control by spraying the plants with water to knock off the pests.
Prevent cucumber diseases by planting resistant cultivars and rotating cukes and related vine crops on a 3- to 4-year basis. Minimize the spread of disease spores by keeping cucumbers away from melons, pumpkins, and squash; avoid handling wet vines. Keep the garden clean and free of perennial weeds, particularly ragweed and ground cherry, which can harbor disease. Here are some common diseases to watch for.
Anthracnose produces hollow, water-soaked spots on the leaves that enlarge and turn brown. It can also blacken and pit the fruits, making them inedible.
Bacterial wilt, spread by cucumber beetles, starts with a single wilted leaf, followed by the wilting of the entire plant.
Downy mildew appears in damp weather and results in irregular yellow or purplish spots on the leaves, which soon curl up and die.
Mosaic, spread by both aphids and cucumber beetles, shows up as rough, yellow-mottled leaves, stunted plants, and whitish fruit.
If these diseases infect your crop, destroy the affected vines or put them in sealed containers for disposal with household trash. Do not put diseased plant material into your compost pile.
Harvesting: Pick cucumbers frequently, before they mature. With some cultivars, especially small pickling types, it may be necessary to harvest daily. If the seeds of even one fruit are allowed to mature, the whole vine will stop producing. Overripe white-spined cucumbers turn creamy white; black-spined ones turn a yellowish orange.
By picking regularly, you can extend the harvest to around 6 weeks. Gently twist or clip off each cucumber, being careful not to break the vines. Cucumbers keep refrigerated for 1 to 2 weeks, but pickling is the best method for longterm storage.
Ribes spp.
Grossulariaceae
It’s hardly surprising that currants have been cultivated for centuries; these easy-to-grow plants produce generous quantities of tasty fruit with very little maintenance. Currants are deciduous shrubs with an upright or spreading habit, growing 3 to 7 feet high and wide. They bear ¼- to ¾-inch-diameter black, red, pink, green, golden, yellow, or creamy white fruit. The black fruits are the most intensely flavored, while the pale whites have a more delicate flavor.
These cold-hardy plants begin growth in very early spring. They flower and fruit on wood that is 1 or more years old. Each bush can continue to yield over a period of 15 to 20 years. When deciding how many bushes to plant, remember that currants can be prolific producers. Five-year-old black currant bushes often yield 10 pounds or more of fruit per bush; red and white types may yield more than 15 pounds. Currants are mostly self-fertile, but many cultivars benefit from cross-pollination, so it’s wise to plant several different cultivars if you have room. Zones 3–5.
Types: Currants encompass several species and hybrids of Ribes. Black currants are R. nigrum (European black currant), R. americanum (American black currant), R. odoratum (clove currant), and R. aureum var. villosum (buffalo currant). Black currants are commercially important for preserves, juices, wine making, and fresh eating. ‘Ben Sarek’ is a highly productive, disease-resistant dwarf variety. ‘Titania’ is tall, but resistant to white pine blister rust. Red and white currants were developed from R. rubrum (red currant) and R. petraeum and their hybrids. Red currants such as ‘Jonkheer van Tets’ and ‘Cascade’ are popular for making intensely colored and flavored jellies and juices.
Planting: Choose a protected site with full sun if possible. Currants do well in partial shade, but the fruit will be more tart. Moist but well-drained loamy soil is ideal; clay soils loosened with organic matter are also good. Avoid poorly drained soils and frost pockets.
Plant red, white, and buffalo currants with the topmost root 1 inch below the surface; other black currants should be 3 to 4 inches deeper than they grew in the nursery. Conditions permitting, you can plant currants from November to early March, although early fall planting is best. Black currants need 8 feet all around them. Space bushes of other currants 5 to 6 feet apart in rows at least 6 feet apart. Rows should run north to south when possible, to allow maximum sunlight to reach each plant.
Care: Currants are shallow-rooted plants, so avoid cultivation after planting. Maintain a 2- to 3-inch mulch layer to hold in moisture and smother weeds; hand-pull any weeds that do emerge. Currants benefit from regular applications of high-nitrogen organic fertilizer. Keep the soil evenly moist; water deeply in dry weather.
Pruning: For red and white currants, the usual form is an open, cup-shaped bush on a 6-foot main stem. To maintain this form, cut back leaders by half and laterals to one to three buds at planting and thereafter every fall. Make cuts just above a downward- and outward-facing bud; remove all suckers from the bottom 6 inches of the stem.
Another popular pruning style for currants is vertical cordons (upright, single-stemmed plants spaced 2 feet apart), ideal for small gardens. Establish cordons by training a single vertical stem up a 6-foot stake. At planting, remove all but one of the leaders; cut back the remaining stem by half and its side branches to a few buds. Keep mature cordons at their desired height by summer-pruning the leader to one bud.
Black currants are grown as multistemmed bushes. Cut each cane back to only two buds above the soil at planting time. In the years after planting, prune back leaders to one-half or one-third of their length and laterals to one to three buds. After the second or third year, also cut a few of the oldest stems to the ground each year to encourage vigorous new growth.
Problems: Imported currantworms are green, caterpillar-like larvae that feed on leaf edges. Control by handpicking or spraying plants with a strong stream of water to dislodge the larvae. Gooseberry fruitworm attacks both currants and gooseberries. Larvae burrow into the fruit just before it ripens, eat the pulp, and then spin a silken webbing joining fruits and leaves. Destroy affected fruit and cultivate lightly under bushes to expose the pupae for birds to eat. Currant borers cause stems to wilt suddenly; prune off affected stems below the entrance hole, and burn them or place them in sealed containers for disposal with household trash.
Diseases include American gooseberry mildew, which causes white powdery patches on leaves and shoots. Some varieties are resistant to the disease. To control mildew, prune shoot tips back by a third and spray the plant with sulfur fungicide or a potassium bicarbonate spray. Leaf spot causes brown patches on leaves, with early defoliation. Clean up affected foliage and fallen leaves. If the infection seems severe enough to threaten the plant’s health, apply a sulfur- or copper-based spray for control.
Historically, a major concern when growing currants was white pine blister rust. This disease needs both a species of Ribes and a white or other five-needled pine to complete its life cycle. While it has little effect on Ribes species, it causes fatal cankers on pine trees. In the early 1920s, the federal government established a ban on growing and selling any Ribes species. In the 1960s, the federal restrictions were removed as white pines became less important as timber trees. Some states still have restrictions. Contact your Cooperative Extension Service to find out if planting currants is permitted where you live. If you have white pines on your property, site Ribes species at least 200 feet away from the trees, or choose rust-resistant cultivars.
Harvesting: Early cultivars are ready for picking in mid-June; later ones, especially some black currants, ripen into September. Pull off entire fruit clusters, rather than the individual fruits. Ripe fruit will stay on the plant for several days. Once picked, though, currants don’t keep well, so use them as soon as possible.
Although you can eat the fruit fresh when it’s fully ripe, currants most often are used in preserves, jellies, and juices. Fruit from mild, sweet black currants also makes excellent wine. White currants are best eaten fresh or canned whole in light syrup. All currants freeze well.
Few things are as satisfying as gathering an armful of the flowers you love in the colors you want. With your own cutting garden, you can grow your favorite flowers and enjoy fresh-cut bouquets all season long.
You may choose to grow flowers for cutting in much the same way as vegetables are traditionally grown for harvest, with all the plants of each species together in rows or raised beds. Or you can mix your cutting flowers in ornamental borders and beds. Each approach has its advantages. If you already grow vegetables, you’ll find that adding cut flowers to the vegetable garden makes it glow with vivid colors. You probably never thought a vegetable garden could be so pretty! When grown in blocks, cut flowers are as easy to tend as vegetables, too. Another advantage of growing flowers for cutting in blocks or rows in a garden specifically designated for cutting is that you won’t deplete the display in other parts of your landscape that you’ve designed to provide outdoor color. Finally, growing cut flowers in rows makes it easy to compare cultivars planted side by side to see which you like better or which grow better for you.
If you want to grow cut flowers throughout your ornamental gardens, interplant annuals and perennials, including ornamental grasses, with bulbs, roses, and herbs to create spectacular mixed beds and borders. To make sure the flowers you cut won’t leave “holes” in your border, grow at least three plants of each perennial intended for cutting and six or seven of each annual. When you design mixed flowerbeds and borders, group the plants of one species or cultivar in masses for the most striking visual effect.
Whether you grow cut flowers in a separate garden or in your regular ornamental beds, you can supplement the materials from your cutting garden with foliage and flowers from the rest of your landscape. Grow roses with other shrubs in a foundation planting, as a border or screen at the edge of the property, or around a deck or patio. Train vines on arbors, trellises, or fences to supply graceful stems for arrangements. Trees and shrubs provide foliage, flowers, berries, and branches for cutting. You can turn a shady spot into a lovely garden of ferns and hostas that will supply foliage for arrangements.
Most cutting-garden flowers prefer full sun with average soil and moisture. Plant different colors and shapes, so you’ll have a variety of flowers to work with. Flower shapes can be grouped by their use in arrangements: linear, for line and height; round, for mass or a focal point; and filler, to unify and add an airy look. Here are some good choices to get you started. Plant names are followed by flower shape and color.
Annuals
Ageratum houstonianum (ageratum, floss-flower): Round; blue, lavender, white, or pink
Antirrhinum majus (snapdragon): Linear; white, pink, red, orange, yellow
Calendula officinalis (pot marigold): Round; yellow, orange
Callistephus chinensis (China aster): Round; white, yellow, pink, red, blue
Coreopsis tinctoria (calliopsis): Round; yellow, red
Cosmos spp. (cosmos): Round; white, pink, red, yellow, orange
Limonium sinuatum (statice): Filler; white, pink, purple-blue, yellow
Matthiola incana (stock): Linear; white, pink, rose, lavender
Salvia spp. (salvias, sages): Linear; red, pink, white, blue, violet
Tagetes spp. (marigolds): Round; orange, yellow, red, bronze, white
Zinnia elegans (zinnia): Round; white, pink, red, yellow, orange
All the perennials listed here are long-blooming, but don’t overlook flowers that bloom in a single season—peonies in early summer or sneezeweeds (Helenium spp.) from late summer to fall, for example.
Achillea spp. (yarrows): Round; yellow, pink, white
Aster spp. (asters): Round; white, pink, red, lavender, blue
Campanula spp. (bellflowers): Round, linear; white, pink, blue
Chrysanthemum spp. (chrysanthemums): Round; white, pink, red, orange, yellow
Delphinium spp. (delphiniums): linear; white, blue, purple
Dianthus spp. (pinks): Round; white, pink
Echinacea purpurea (purple coneflower): Round; mauve, white
Echinops spp. (globe thistles): Round; blue
Gaillardia spp. (blanketflowers): Round; yellow, red, orange
Gypsophila paniculata (baby’s breath): Filler; white
Leucanthemum × superbum (Shasta daisy): Round; white
Liatris spp. (blazing stars): Linear; white, pink, purple, magenta
Penstemon spp. (penstemons, beardtongues): Linear; red, pink, white, purple, blue
Phlox spp. (phlox): Round; white, pink, red, orange, lavender
Rudbeckia spp. (coneflowers): Round; yellow
Salvia spp. (sages): Linear; purple-blue
When you’re deciding which plants to include in your garden, remember to grow a variety of plant forms, so you’ll always have the right shapes for any arrangement. Satisfying arrangements generally have three primary elements: tall, spiky flowers and foliage for line; large, flat, round flowers and foliage for focal points or mass; and small, airy flowers and foliage for fillers.
Choose plants that bloom for a long period and hold up well as cut flowers. Many annuals bloom almost nonstop during summer; most perennials flower for a week to well over a month. Make sure you grow flowers that bloom at different seasons to have bouquets indoors throughout the year.
Think first about color when selecting the flowers you’ll grow. The most effective arrangements coordinate with the colors in your home—you wouldn’t want orange flowers in a pink room, for example. If one color predominates in the house, grow flowers that complement that color.
Height also matters when choosing plants for cutting. For flower arrangements, it is easier to use longer stems. New cultivars of annuals and perennials frequently are shorter, more compact-growing plants. As you choose plants, note the mature blooming height.
Growing fragrant flowers makes both gardening and flower arranging more pleasurable. Scented perennial flowers that are good for cutting include lily of the valley (Convallaria majalis), peonies (Paeonia spp.), many pinks (Dianthus spp.), and garden phlox (Phlox paniculata). Annuals such as flowering tobaccos (Nicotiana spp.), stocks (Matthiola spp.), sweet pea (Lathyrus odoratus), and bells of Ireland (Moluccella laevis) are also good choices. Don’t overlook trees and shrubs such as lilacs, magnolias, and roses.
Most herb foliage, flowers, and seed heads can bring fragrance as well as form to arrangements. For example, try using dill (Anethum graveolens), fennel (Foeniculum vulgare), lavenders (Lavandula spp.), lemon balm (Melissa officinalis), lemon verbena (Aloysia triphylla or A. citrodora), mints (Mentha spp.), or rosemary (Rosmarinus officinalis).
Among the best hardy bulbs for cutting are daffodils, hyacinths, irises, lilies, tulips, alliums (Allium spp.), grape hyacinths (Muscari spp.) and montbretias (Crocosmia spp.). Tender bulbs that make great cut flowers include dahlias, gladioli, tuberous begonias, African lilies (Agapanthus spp.) as well as tuberose (Polianthes tuberosa).
To grow cut flowers successfully, choose the planting site carefully and prepare the soil well. Most of the plants you’ll want to grow for cutting will thrive in well-drained, humus-rich soil and full sun. Check the cultural requirements of the specific plants you’ve chosen and group plants with similar needs together.
To produce the best-quality cut flowers and foliage, your plants will need top-notch care. Give them adequate water and fertilizer, be diligent about weeding and deadheading (removal of faded flowers), and provide winter protection and pest control when necessary. Laying an organic mulch, such as compost or shredded leaves, conserves moisture, inhibits weeds, and keeps flowers and leaves clean and mud-free. Commonsense care and careful plant selection will give you a constant supply of beautiful cut flowers all season.
Plants have the amazing capacity to regenerate from small pieces of tissue called cuttings. These small portions of stems, leaves, or roots will form new roots and shoots if given the right treatment.
Taking cuttings is the most common way to propagate many types of ornamental plants. Because raising plants from cuttings is an asexual type of reproduction, the new plants will look exactly like the parent.
All types of cuttings need a medium to support them while they grow roots and some type of structure to protect them during the rooting period. It’s also important to observe good sanitation to minimize disease problems.
Media: The best media for rooting cuttings are moisture retentive but well drained and free of insects, diseases, and weed seeds. Commonly used media are sand, perlite, vermiculite, and peat moss. No one material or combination is ideal for all plants, but an equal mixture of vermiculite and sand or perlite is useful in most situations. Soil is not a good propagation medium, especially in containers. Unlike the other materials, soil is not sterile and can compact severely from frequent waterings. Only very hardy cuttings are planted directly into soil.
Some plants, such as various houseplants, coleus, and willows (Salix spp.), will root directly in water. This method is fun to try, but if you want to save the cutting, plant it in potting soil while the roots are still small. Plants may have difficulty adapting to soil if their roots remain in water too long.
Structures: Cuttings need a protected, high-humidity environment while they root. Cuttings don’t have roots to take up water, but they still lose moisture through their leaves. Keeping the surrounding air moist minimizes water loss and helps cuttings survive until they can support themselves.
On a small scale, plastic bags are great for protecting cuttings. Support the bag so plastic does not rest on the cuttings and encourage rot. (A wire frame made from a coat hanger works fine for this.) Provide ventilation by occasionally opening the bag for an hour or two. In most cases, you won’t have to add water until the cuttings form roots. To harden off rooted cuttings, gradually open the bag for longer periods.
For large numbers of cuttings, a cold frame or greenhouse is more practical (see the Cold Frames and Greenhouse Gardening entries). You can set pots of cuttings on the soil or plant directly in the soil inside a cold frame. Close the frame and cover the glass with shading material, such as cheesecloth or wooden laths (like snow fencing or lattice); gradually remove the shading when roots form. Ventilate and harden off by gradually opening the cold frame for longer periods.
Sanitation: Since crushed plant tissue is an invitation to rot, use a clean, sharp tool (such as a knife or scissor-type pruning shears) to collect and prepare cuttings. Never propagate from diseased or insect-infested plants. Plant cuttings in fresh, sterile propagation mix that is stored in closed containers. Pots and propagation areas should be scrubbed clean and, if possible, sanitized by rinsing with a 10 percent bleach solution (one part bleach to nine parts water). Check plants often during rooting and remove any fallen leaves or dead cuttings. Don’t overwater; do provide adequate ventilation.
Don’t overlook foliage when you’re cutting flowers for arrangements. Adding beautifully colored, textured, shaped, or variegated foliage can integrate the different shapes and colors of your flowers and give an arrangement added charm and sophistication.
Herbs are a great choice for arrangements. The delightfully aromatic leaves of scented geraniums (Pelargonium spp.), artemisias, and lavender cotton (Santolina chamaecyparissus) add a special dimension to a vase of flowers. Annuals and tender perennials also are great for adding foliage color to arrangements. Consider planting caladiums (Caladium spp.) or coleus (Plectranthus scuttellarioides) for showy foliage to include in arrangements as well.
Many perennials produce interesting foliage along with their flowers, including lady’s mantle (Alchemilla mollis), ligularias (Ligularia spp.), and lamb’s ears (Stachys byzantina).
Shade-loving plants such as ferns, hostas, pachysandra, and bergenias (Bergenia spp.) are easy to grow and offer a range of texture and leaf shapes. In addition, some hostas and pachysandras have variegated foliage, which can add color and drama to any arrangement.
Don’t neglect your trees and shrubs when scouting for foliage to enhance arrangements. Evergreens such as boxwoods (Buxus spp.), false cypresses (Chamaecyparis spp.), spruces (Picea spp.), yews (Taxus spp.), and hemlocks (Tsuga spp.) supply attractive foliage all year. Hollies (Ilex spp.), Japanese aucuba (Aucuba japonica), cherry laurel (Prunus laurocerasus), and magnolias are other good choices.
Rooting hormones—synthetic versions of natural plant hormones—can encourage root formation on stem cuttings of difficult plants and increase the number of roots on others. Commercial rooting hormones are usually available at garden centers in powder form; be aware that some products contain chemical fungicides. Product labels will suggest uses, or experiment with treated and untreated cuttings.
A solution known as willow water can encourage rooting. Cut willow stems into 1-inch pieces and place them in a small container; add about 2 inches of water, cover, and let stand for 24 hours. Remove the stems, insert cuttings, and let them soak overnight before planting.
Take softwood cuttings from succulent spring growth of woody plants such as azaleas and magnolias. Treat stem cuttings of herbaceous plants like softwood cuttings, including annuals or tender perennials such as coleus, geraniums, and impatiens. Because these cuttings are from young tissue, they form roots easily but need high humidity to prevent wilting.
Season: Take softwood cuttings from April through June, when new leaves are fully expanded but stems are still soft. Take houseplant cuttings any time; take tender perennial cuttings for overwintering in late summer.
Getting started: Water the parent plant a day or two before taking cuttings. Fill a container with moist propagation mix.
Method: Collect cuttings in the morning or on cloudy, cool days, and keep them moist until planting. Cuttings should be 3 to 6 inches long; they usually include a terminal bud. Remove leaves from the lower half of the stem, and apply rooting hormone if desired. Insert the cutting to about one-third of its length, firm the medium with your fingers, and water to settle the cutting. Enclose the container in plastic, or place it under a mist system in a cold frame or greenhouse.
Aftercare: Ventilate plants; water as needed to keep the medium moist but not wet. Softwood and herbaceous cuttings root quickly, often in 2 to 4 weeks. When roots appear, harden off the cuttings and transplant to a pot or into the garden.
Softwood and herbaceous cuttings. Take these cuttings from stems that snap when bent. Remove the cutting just below a node; discard the stem piece left on the parent down to the uppermost node.
Take hardwood cuttings from woody plants during their dormant period. Hardwood cuttings don’t require high-humidity conditions. This method is effective for some types of woody plants and vines, including grapes, currants, willows, and some roses.
Season: Take cuttings after leaf fall and before new growth begins in spring. Mid-autumn is often the best time to collect and plant cuttings, so they can form roots before the buds begin to grow.
Getting started: For potted cuttings, fill the container with moist propagation mix. If you are planting cuttings outdoors or into a cold frame, prepare a deep, well-drained nursery bed.
Method: Collect 4- to 8-inch cuttings from vigorous, 1-year-old wood, a few inches below the terminal bud. Make a sloping cut at the top, slightly above a bud, and a straight cut at the base, slightly below a bud. Stick cuttings 2 to 4 inches apart in the medium, with the top bud about 1 inch above the surface. Be sure the cuttings point upward: Double-check that you’ve stuck the ends with straight cuts into the medium. Plant fall cuttings soon after they are taken, or store them upside down in moist peat moss or perlite and plant right side up in spring. Cover fall-planted cuttings with 6 to 8 inches of mulch to prevent frost heaving; remove mulch in spring. Plant late-winter cuttings directly into pots or soil.
Aftercare: Keep cuttings moist. They usually root rapidly in spring, but it is best to leave them at least until fall. Transplant rooted cuttings to the garden or into pots.
Hardwood cuttings. Take simple cuttings from the midsections of branches. For difficult-to-root plants, take a heel or mallet cutting, each with a bit of older wood at the base.
Broad-leaved and needled evergreens are often propagated by stem cuttings. Try this method on plants such as arborvitaes (Thuja spp.), hollies (Ilex spp.), and boxwoods (Buxus spp.).
Season: Collect broad-leaved cuttings in late summer. Take needled cuttings in fall or winter; yew and juniper cuttings should have had some frost.
Getting started: Fill a container with moist propagation mix, or prepare a well-drained bed in the base of a cold frame.
Method: Collect 4- to 6-inch tip cuttings in the proper season. Some cuttings benefit from a piece of older wood—a heel—left at the base of the stem. To take a heel, pull sharply downward on the base of a side shoot as you remove it from the parent plant; trim the excess with a knife.
Wounding is another way to encourage the rooting of difficult plants. Create a wound by cutting a shallow sliver on the side of the cutting near the base. This process stimulates cell division and enhances water uptake but also increases the chance of disease problems.
Before planting, remove lower leaves and side shoots. To save space with large broad-leaved cuttings, cut each remaining leaf in half. Apply rooting hormone if desired. Plant cuttings to about one-third of their length, firm the soil, and water to settle the cuttings. Place potted cuttings indoors in a plastic bag or in a greenhouse; alternately, set pots in a cold frame, or plant directly into the frame.
Aftercare: Ventilate and water if necessary. Once roots appear, gradually harden off the cuttings. The new plants are best left in place until autumn and then planted in the garden or in a pot.
Broad-leaved evergreen cuttings. To save space in flats, you can remove up to half of the leaves from a cutting, and for broad-leaved cuttings, cut off half of each remaining leaf. Some broad-leaved evergreen cuttings benefit from wounding: Use a sharp knife to make a shallow 1-inch cut, or wound, at the stem base.
The easiest way to reproduce some perennials, including bear’s breeches (Acanthus spp.) and globe thistles (Echinops spp.), is to dig and root the roots.
Season: Dig roots in late winter or early spring. Collect pencil-thick roots from larger perennials; thinner ones from plants such as drumstick primroses (Primula denticulata). Collect roots from bleeding hearts (Dicentra spp.) and Oriental poppies (Papaver orientale) in midsummer.
Getting started: Fill a pot with moist propagation medium.
Method: Remove soil from around the base of large perennials and cut off several pencil-thick roots. For smaller plants, dig the entire clump, wash off the soil, and clip off roots. Place cuttings immediately in a plastic bag. Cut roots into 2- to 3-inch-long sections. Since cuttings must be planted “right side up,” make a straight cut at the top of the root, nearest the plant, and slanted cuts away from the plant. Stick the cuttings in the propagation medium with the tips just under the surface. Or lay them horizontally, just under the soil surface.
Aftercare: Water thoroughly to settle the cuttings, then keep them moist, but not wet. Wait until you see roots emerging from the bottom of the pot before moving them to larger pots or the garden, since root cuttings frequently produce topgrowth before they have adequately rooted.
Some plants with thick or fleshy leaves can produce roots and shoots directly from leaf pieces. This is a popular method for houseplants such as African violets, many fancy-leaved begonias, and snake plants (Sansevieria spp.).
Season: Take cuttings any time of the year. Use healthy, young, but fully expanded leaves.
Getting started: Thoroughly water the parent plant a day or so before collecting cuttings. Fill a container with moist propagation medium.
Method: Cut snake plant and streptocarpus leaves into 2-inch-long pieces. Plant the pieces right side up, about 1 inch deep. Peperomias and African violets are reproduced by leaf petiole (the stem that supports the leaf) cuttings. Detach a leaf along with 1½ to 2 inches of its petiole. Plant vertically or at a slight angle, so the petiole is buried up to the leaf blade. After planting, water the cuttings to settle them in the soil. Begonias can be propagated with whole leaves: Make three or four cuts across the veins of fancy-leaved types, then pin them to the soil surface with pieces of wire.
Aftercare: If excessive condensation occurs, ventilate the cuttings. When new leaves appear, usually in 6 to 8 weeks, gradually harden them off. Sever plantlets from the parent leaf if it has not already withered away; transfer rooted plants to pots.
Try these tips for best success with cuttings.
•Plant large numbers of cuttings in wooden or plastic flats; use pots for small quantities.
•Cuttings are usually 4 to 6 inches long, but they can be shorter if the stock plant is small; get at least two nodes (leaf-stem joints). Nonflowering shoots are best. Remove flowers and flower buds from unrooted cuttings.
•Soil warmth encourages root formation. Place containers of cuttings on a propagation mat, a board over a radiator, or the top of your refrigerator.
•Don’t tug on cuttings—check the bottom of the container to see if roots are visible.
•Be adventurous! Try different techniques on a range of plants to see what works for you. Label your experiments and record results for future reference.
