See Papaver
Portulaca, moss rose. All-season annuals.
Description: Portulaca grandiflora, moss rose, produces 1-inch single or double roselike flowers, in white, pink, red, yellow, orange, or magenta bloom freely on sprawling, 4- to 6-inch mats of succulent, needlelike leaves.
How to grow: Sow seeds directly after the soil warms up, or set out transplants no more than 6 inches apart. Plants thrive in sunny, hot, dry areas with poor soil. Plants self-sow readily, but the flower color may revert to bright magenta.
Landscape uses: Use portulaca as a filler between paving stones and cracks. It also adds color to pots and baskets.
Solanum tuberosum
Solanaceae
Growing potatoes is fun as well as practical, thanks to the development of disease-resistant varieties and varieties in a range of colors, shapes, and sizes. Native to the Andes mountains of South America, potatoes thrive in the cool northern half of the United States and the southern half of Canada. Growers in other areas, however, can have successful crops by planting potatoes in very early spring or, in warm regions, in fall or winter for a spring harvest.
Planting: Although you can grow some potato varieties from seed, it’s easier to plant certified, disease-free “seed potatoes” purchased from garden centers or Internet and catalog suppliers. (Potatoes you buy at the grocery store often are chemically treated to prevent the eyes from sprouting.) You’ll need 5 to 8 pounds of potatoes to plant a 100-foot row. Along with standards such as ‘Kennebec’, try some fingerlings, such as ‘Russian Banana’ or ‘French Fingerling’, and those with colorful tubers like ‘Rose Gold’, ‘Adirondack Red’, ‘Adirondack Blue’, ‘Purple Peruvian’, or ‘Cranberry Red’.
Potatoes need space, sunshine, and fertile, well-drained soil. Acid soil provides good growing conditions and reduces the chance of a common disease called scab.
Plant seed potatoes whole, or cut them into good-sized pieces, each of which should contain two or three eyes. Cure the cut pieces by spreading them out in a bright, airy place for 24 hours, or until they are slightly dry and the cut areas have hardened. In wet climates, some gardeners take the precaution of dusting seed potatoes with sulfur to help prevent rot.
Plant early cultivars 2 to 3 weeks before the last spring frost, or as soon as you can work the soil. Folklore advises planting potatoes on St. Patrick’s Day; however, that recommendation only works if your garden is snow-free by March 17! Time the planting of late cultivars so they will mature before the first fall frost.
Plant potatoes in rows spaced 3 feet apart. Place the seed pieces 6 inches apart, and cover them with 4 to 5 inches of soil. As the vines grow, hill soil, leaves, straw, or compost over them to keep the developing tubers covered. (When exposed to sunlight, tubers turn green and develop a mildly toxic substance called solanine.) Leaving only a small portion of the growing vines exposed encourages additional root development.
Many growers prefer to plant potatoes in hills. The illustration shows potatoes planted in soil hills and mulch mounds. The mulch-planting method is especially good for growing potatoes in containers, such as large barrels. This “dirtless” method makes harvesting extremely clean and easy but can produce a smaller crop of small tubers.
Growing guidelines: Once the plants blossom, stop hilling up the soil, and apply a thick mulch to conserve moisture and keep down weeds. Water deeply during dry spells.
Planting potatoes. Dig furrows about 6 inches deep, space the seed pieces 6 inches apart, and hill up the soil around the stems as they grow. Or spread compost or shredded leaves over the surface of your potato bed, space your seed potatoes evenly over the mulch, and top with about a foot of straw or hay.
Problems: Climate and growing conditions can create a number of problems. Speckle leaf, a disorder that appears as dark splotches on leaves with sunken areas on the leaf undersides, is apparently caused by too much ozone in the atmosphere. Breeders are developing resistant cultivars. Keeping plants healthy and well cultivated is the best prevention.
Hollow areas in tuber centers are caused by rapid and uneven growth. To prevent this, plant seed potatoes closer together, cut down on watering and fertilizer, and avoid susceptible cultivars.
Potatoes are attractive to several kinds of pests, including aphids, Colorado potato beetles, cutworms, and flea beetles. For control measures, see The Top 10 Garden Insect Pests.
Other possible pests include blister beetles, leaf-hoppers, and wireworms. Blister beetles are ¾ inch long, slender, dark-colored insects that feed on leaves; reduce damage by handpicking (be sure to wear gloves to avoid blisters). Thin, wedge-shaped, ¼-inch-long leafhoppers cause leaves to curl and yellow; apply soap spray for control. Wireworms are ½- to ¾-inch-long larvae of the click beetle; these orange “worms” feed on and damage developing tubers. They are more prevalent in newly cultivated areas, so wait a few years after converting a lawn area into garden to plant potatoes there; crop rotation and frequent cultivation can also help, as can wireworm traps like those described in food traps.
An intriguing development in pest control is varieties such as ‘Prince Hairy’ and ‘King Harry’. These varieties discourage leafhopper and Colorado potato beetles from feeding by virtue of their hairy leaves. The hairs contain sticky fluid that leaks out when hairs are touched, coating the insects with goo.
Avoid most potato diseases by rotating crops, providing good air circulation, keeping the garden clean, selecting resistant cultivars, and planting disease-free seed potatoes. If disease does strike, remove and destroy affected plants. Here are some diseases that might occur.
Black leg, a bacterial infection, begins as yellowing of top foliage and progresses to a black, slimy rot that destroys stems and tubers.
Early blight, also called leaf spot, is a fungus that shows up on leaves as enlarging brown spots that develop concentric rings. The blight eventually spreads to the tubers, reducing yields and creating puckered skins with discolored spots.
Late blight hits crops after they’ve blossomed. It begins with dark, watery spots on leaves and spreads to stems and tubers.
Ring rot is a highly infectious bacterial disease that is not generally obvious aboveground. Underground, it starts with a ⅛-inch ring of decay under a tuber’s skin; eventually the whole interior decays, leaving a shell of firm tissue.
Scab causes rough, corky spots on tubers. It is most commonly a problem in soils that have a near-neutral or alkaline pH or in those that are on the dry side. Keep the pH low and maintain an even moisture level in the soil to avoid scab.
Verticillium wilt turns older leaves yellow and eventually causes the whole plant to wilt and die.
Harvesting: Blossoming plants are a sign that the first “new” potatoes are ready to harvest. Pull aside the earth around the base of plants and gently pick off cooking-size tubers, which are delicious boiled with the skins on.
Once the foliage starts to wither and die back, the tubers will be fully grown. If the weather is not too warm or wet, they will keep in the ground for several weeks. Dig them up with a spading fork before the first frost. Potatoes that are nicked or bruised during harvesting won’t store well, so eat them as soon as you can. Clean and dry the crop as quickly as possible, but never expose it to sunlight. Store tubers in a dark place at around 40°F.
Note that potatoes with colored flesh often lose that color when cooked in water. To keep red and purple potatoes colorful, try roasting them instead of boiling.
Primrose. Spring-blooming perennials.
Description: Primroses bear rounded, five-petaled flowers in clusters above dense rosettes of paddle-shaped, wrinkled leaves.
Primula × polyantha, polyanthus primrose, practically hides its 6-inch paddlelike leaves in early spring under 8- to 12-inch-tall, dense clusters of 1½-inch blooms in rich shades of white, yellow, red, and blue, many with a distinct yellow eye. Best in Zones 5–7; widely grown as annuals elsewhere.
P. sieboldii, Siebold’s primrose, carries its 1½-inch blooms in white, lilac, pink, and magenta-purple shades 8 to 10 inches above spreading masses of scalloped 4-inch leaves that die down in summer. Zones 4–8.
P. vulgaris, English or common primrose, bears yellow, 1-inch, slightly fragrant blooms just above dense rosettes of 3-inch leaves. Zones 4–8.
How to grow: Plant in spring or divide after bloom every 2 to 3 years. Grow in partially shaded, average to fertile, well-drained but moisture-retentive soil enriched with organic matter. They tolerate full sun if the soil remains moist, although common primroses tolerate drier soils than most. Individual plants are usually short-lived, but they self-sow or produce offsets generously. Mulch in summer to retain moisture and in winter to prevent the shallow-rooted plants from being heaved out of the ground by the freezing and thawing of the soil. Handpick or trap slugs and snails; wash spider mites off plants with a strong spray of water.
Landscape uses: Group primroses along paths, at the edge of borders, and in cottage gardens. Combine with bulbs, ferns, and other spring flowers in a wooded area. Make a late sowing of sweet alyssum to fill bare spots left by dormant Siebold’s primroses.
See Ligustrum
Learning to propagate plants—to make new plants from existing ones in your home and garden—is one of the most exciting and rewarding aspects of gardening. Many of the methods are easy, and you don’t need fancy or expensive tools. Propagation is cheaper than buying large numbers of plants, so with a little time and effort you can fill your garden quickly at minimal cost. Propagating new plants will keep your house and garden full of vigorous specimens, and you’ll probably have plenty to give away, too!
You can reproduce most plants by several methods. There are two major types of propagation: sexual and asexual. Sexual propagation involves seeds, which are produced by the fusion of male and female reproductive cells. Asexual propagation methods use the vegetative parts of a plant: roots, stems, buds, and leaves. Division, cuttings, layering, budding, and grafting are all asexual methods. Spores (produced by ferns and mosses) may look like seeds, but they are technically asexual structures, because they have a specialized way of forming new plants.
Select a technique by considering the plant you are working with, the materials you have, the season, and the amount of time you are willing to wait for a new plant.
Seeds: Growing from seed is an inexpensive way to produce large numbers of plants. Annuals, biennials, and vegetables are almost always reproduced by seed. You can also grow perennials, shrubs, and trees from seed, although the seedlings they produce may not resemble the parent plants. Raising seeds requires few materials: a container, a growing medium, and seeds. The time to sow seeds depends on the type of plant. For most garden plants, you can sow seeds indoors in late winter or outdoors in spring. Tree, shrub, and many perennial seeds may need a cold period or other treatment before they will germinate. Depending on the type of plant, it could take anywhere from weeks to years to get a garden-size specimen. For complete information on growing plants from seeds, see the Seed Starting and Seed Saving entry.
Spores: Spores are the reproductive structures of ferns and mosses. To produce new plants, sow these dustlike “seeds” on a sterile medium and cover them to maintain humidity and prevent contamination. Clear plastic shoe boxes or cups are ideal containers for propagation. You can collect spores from your own ferns or buy them from specialty catalogs. You can sow spores whenever they are available. The new plants will be ready for the garden after a period of months or years, depending on the species.
Division: Division is an easy way to produce more plants with almost 100 percent success. This method involves digging up an established plant and separating it into several pieces. Division is used for bulbs and mat-, clump-, or crown-forming plants, including ferns, bamboos, bugleweed, daylilies, and hostas. Single-stemmed plants like trees cannot be divided.
All you’ll need for division is a tool to dig up the plant and your hands or a sharp implement to separate the pieces. You can divide most plants in either spring or fall. Division produces full-size plants that can be placed directly in the garden. For more information, see the Division entry.
Cuttings: Cuttings are pieces of leaves, stems, and/or roots that are separated from a parent plant. When placed in the proper conditions, these pieces form new roots and shoots. Stem cuttings are used for a wide range of plants, including geraniums, pachysandra, and coleus. Use root cuttings for perennials such as Oriental poppies (Papaver orientale) or globe thistles (Echinops spp.) and some trees, including golden rain tree (Koelreuteria paniculata). You can also try leaf petiole cuttings, used for African violets and peperomias, and leaf pieces, used for such plants as gloxinias and snake plant (Sansevieria spp.).
The materials you’ll need depend on the plant and the method you are using. Leaf petiole cuttings of African violets will root in a simple glass of water. You can stick stem and root cuttings in a pot or flat of regular potting soil. A plastic bag or other clear cover will help to maintain high humidity around the cuttings. More complicated structures, such as cold frames and mist boxes, are good for hard-to-root shrub and tree cuttings. Plants reproduced by cuttings can be ready for the garden in a matter of weeks or months. See the Cuttings entry for more details on this method.
Layering: Layering is a way to get stems to root while they are still attached to the parent plant. Some plants produce layers naturally. Strawberries form rooted plantlets on runners; raspberries produce new plants where the stem tips touch the ground. The technique of simple layering involves bending a low-growing stem to ground level and burying a few inches of the stem behind the tip. Simple layering is an easy way to reproduce such plants as camellias, forsythias, and magnolias. To air-layer, you shallowly wound a stem a few inches below the tip to stimulate root production, and then wrap moist sphagnum moss around the stem. Covering the moss with a thin sheet of plastic holds in moisture and secures the moss to the stem. Weeping fig trees (Ficus benjamina), corn plants (Dracaena fragrans), and witch hazels (Hamamelis spp.) are all good candidates for air layering.
You don’t need much equipment to try these techniques. A trowel (for digging the trench) is sufficient for simple layering. For air layering, you’ll need sphagnum moss, waterproof tape, a piece of thin plastic, and a knife. Early spring is the best time for simple layering. For outdoor plants, you can set up air layers in spring or late summer. Indoor air layers can be started anytime. It will probably take several months to a year to get a new well-rooted plant. For more information, see the Layering entry.
Grafting: Grafting is a more advanced propagation technique. It involves joining a stem piece of one plant (the scion) to the root system of another plant (the rootstock) in such a way that the parts unite and continue to grow. You can reproduce many types of trees by grafting, including pines (Pinus spp.) and rhododendrons, and even some herbaceous plants, such as cacti. Grafting has several advantages over other propagation methods. It allows you to propagate plants that are difficult to raise from seeds or cuttings. Through grafting, you can produce a plant adapted to your particular needs. Some rootstocks have a dwarfing effect, while others encourage vigorous topgrowth. They can also provide tolerance to soilborne insects and diseases, or to less-than-perfect soil conditions.
The most important grafting tool is a sharp knife. You may also need string or tape (to keep the graft pieces together) and grafting wax (to prevent water loss and avoid contamination). You’ll have to have suitable rootstocks, too. You can raise your own from seeds or cuttings, or buy them from a specialty catalog or nursery. Spring is the most common time for grafting. Herbaceous plants will join successfully in a few weeks; woody plant grafts usually take a month or two to unite firmly and begin growing. See the Grafting entry for more details on this technique.
Budding: Budding is a particular type of grafting. In this method, you use only a single bud from the desired plant. Budding is commonly used to propagate fruit trees as well as ornamentals, such as hybrid tea roses. For the home gardener, the advantages of budding are similar to those of grafting. In some cases, budding is more successful than grafting because it is easier to get close contact between the bud and the rootstock. Budding also allows you to propagate more plants if you have a limited amount of scion material.
For this technique, you’ll need a sharp knife and some string or tape to secure the bud to the stem. As with grafting, compatible rootstock plants are necessary. Budding is best done in late summer or early fall. Buds inserted at this time will produce new growth the following spring. See the Budding entry for a more complete discussion of this technique.
Pruning and training are both a science and an art—and probably the least-understood gardening practices. Proper pruning and training bring out the best in each plant. Not only do well-pruned plants produce more and better fruit and flowers, they also are healthier and more vigorous. Pruning and training can improve the health of an ailing plant, make trees stronger and safer, channel growth away from buildings or traffic, and restore a sense of order to an overplanted or overgrown yard.
While pruning and training are most often thought of as techniques used on woody trees, shrubs, and vines, they’re also used to direct the growth of herbaceous plants. Roots can be pruned as well to prepare a plant for transplanting or to encourage the roots of a new plant to branch out into the surrounding soil. The roots of bonsai trees are pruned to restrict growth.
Pruning can be used to:
Remove diseased and dead wood.
Encourage branching and bushy growth.
Direct a plant to grow in a particular direction.
Eliminate unattractive, crowded, and congested growth.
Increase the structural strength of a tree or shrub.
Reduce the overall size of a tree or shrub without causing rampant regrowth.
Improve air circulation and reduce disease problems.
Increase flowering and vigor by removing old, nonblooming wood.
Help a newly planted plant become established.
Eliminate reverted growth (such as all-green shoots on an otherwise variegated plant).
Most pruning comes down to making one of two kinds of pruning cuts: thinning cuts and heading cuts.
Thinning cuts: Thinning cuts remove branches totally. They open up a plant but don’t make it shorter. Thinning directs growth into alternate patterns. Use thinning cuts to establish good structure of young trees and shrubs and to allow sunlight and air to reach the interior of a plant. Also use thinning cuts to remove unattractive or unruly branches, branches that block a view, and any stems that rub or cross. Thinning cuts can eliminate sharp crotches and make a plant less likely to break under a heavy snow load.
Heading cuts: Heading cuts shorten plant stems and stimulate latent buds behind the cut to grow, making the plant more dense. Selective heading reduces overall size or height of a plant without changing its natural shape. The plant suffers less stress, and selective heading doesn’t cause vigorous, out-of-control growth the way that non-selective heading does. To make a selective heading cut that will direct plant growth, cut just above a bud or branch that’s pointed in the direction you want the growth to go.
Nonselective heading is the technique used to shape formal hedges and topiary. Pruning encourages growth, and nonselective heading cuts cause a burst of growth from all of the cut stems. Branches are cut back partway along the stem, resulting in rapid, bushy regrowth just below the cut. Nonselective heading is often mis-applied, resulting in forlorn lollipop-shaped shrubs or trees that would look more attractive, and would likely be healthier, if pruned to follow their natural form. Selective heading combines the best of thinning and heading, but it can’t be applied to all plants. The older, larger, and woodier the plant, the fewer selective heading cuts should be used.
Branch collar. The part of the trunk that helps hold the branch to the trunk, often recognizable as a bulge at the base of the branch.
Branch crotch. The angle where a tree branch meets the trunk or parent stem.
Cane. A long, slender branch that usually originates directly from the roots.
Leader. The main, primary, or tallest shoot of a tree trunk. Trees can be single-leadered or multiple-leadered.
Pinching. Nipping out the end bud of a twig or stem with your fingertips to make the plant more compact and bushy.
Thinning cut. Cutting a limb off at the base, either at ground level or at a branch collar.
Heading cut. Cutting a branch back to a side bud or shoot.
Skirting or limbing up. Pruning off the lower limbs of trees.
Sucker. An upright shoot growing from a root or graft union; also, in common usage, straight, rapid-growing shoots or watersprouts that grow in response to wounding or poor pruning.
Espalier (pronounced is-PAL-yuhr). A fruit tree or an ornamental shrub that is pruned to grow in a flat plane. Although sometimes freestanding, an espaliered plant is generally attached to a framework against a wall and is usually trained in a well-defined pattern.
Topiary. Plants sculpted into sheared geometric shapes or likenesses of animals or people.
Making thinning and heading cuts. Make thinning cuts at the branch collar where the branch originates. Avoid a flush cut; leave the branch collar intact, but don’t leave a stub. To make selective heading cuts, cut directly above a bud or side branch that’s pointing in the direction you want the new growth to take.
Proper technique: Prune from the bottom up and, in the case of large plants, from the inside out. Prune out all dead wood first—an important step for health and good looks. Dead wood is easiest to spot in summer because the branches have no green leaves. Also remove diseased and damaged wood.
Next look for a few of the worst rubbing, crossing branches. Leave the best-placed one of any pair. Try to keep branches that head up and out from the center or that fill an otherwise empty space. Step back from the plant you’re working on frequently and look at it from all angles.
Prune to open up center areas and to clean up the base of shrubs. This improves plant health by admitting light and increasing air circulation. It also has a large impact on the beauty of a plant. Depending on what shrub you are pruning, you may want to concentrate on removing excess twiggy growth or removing a few of the older stems that no longer bloom well.
Selectively thin or head back misplaced branches: those that touch the ground, lay upon or crowd other plants, or come too close to the house, windows, and walkways.
Save any heading cuts until the end of a pruning job. Locate the longest, most unruly branch first, follow it down inside the shrub, and cut it off to a side branch or a bud. Remember: Next year’s new growth will be channeled into the bud or side branch you cut above, so choose which way you want growth to go.
Pruning large limbs: A large branch that is sawed from above will tear bark from the trunk as it falls. Use the three-cut method shown in the illustration to prevent damage when removing large limbs.
1.About 1 foot out from the trunk, cut halfway through the branch from underneath.
2.A few inches in from the first cut, saw off the branch from the top.
3.Remove the stub by cutting along, but never into, the branch collar. On tight crotches, saw from the bottom up.
Pruning mistakes: The most common pruning mistake is to cut back everything in the yard in an ill-fated attempt to make it all smaller again. This actually stimulates an upsurge of messy regrowth, making the final solution more difficult. Tree topping, indiscriminate shearing, and overthinning are the three major forms of “malpruning.” Instead, plan to correct the sizes and shapes of your landscape plants by pruning them properly over the course of several years. If a tree or shrub is simply too large for its site, remember that removing it is one option. You can also hire professionals to transplant even fairly large shrubs or trees that are in the wrong place, so don’t be afraid to ask at your local nursery.
The cure for badly pruned plants is time. Most will reestablish their natural habits given a few years to recover. Rehabilitative pruning can hasten the process and make plants look better. Meticulously prune all dead wood, removing all stubs. Use thinning cuts to simplify tangled branch ends. Take out entire canes. If treelike shrubs have rampantly produced suckers because of heading cuts, slowly remove the worst of them over a period of years. Let the strongest and best-placed suckers grow back into branches. Some plants, including cane growers like weigela, mock oranges (Philadelphus spp.), and forsythia, can be radically renovated by cutting them entirely to the ground. In about 3 years they’ll regrow to mature size and bloom again. Many lovely but rampant vines are treated this way to good effect.
Most needled evergreens will not regrow once they are cut back to wood that does not have needles on it. This makes their size difficult to control and radical renovation impossible.
Nonselective heading cuts. To trim a hedge or shear branches to a uniform surface, make nonselective heading cuts anywhere on the stem.
Pruning large limbs. Make three cuts in the order shown to safely remove a large limb without causing bark tears.
Plan your pruning schedule depending on what you want to accomplish. Removing dead and diseased wood, as well as general thinning can be done in any season. Follow these seasonal guidelines.
Spring pruning stimulates the most rapid regrowth, so it’s a good time for heavy pruning. Prune evergreens in spring, but avoid pruning deciduous trees as they leaf out. Prune spring- and early-summer-flowering shrubs such as azaleas and rhododendrons as soon as they finish blooming, so they’ll have time to grow and set new buds during summer.
Cut shrubs that flower in summer or fall on the current season’s growth back in spring as buds begin to swell. This includes Russian sage (Perovskia atriplicifolia) and bluebeard (Caryopteris × clandonensis).
Summer pruning has a less stimulating effect on growth. Hot or dry weather is extremely stressful for plants, so avoid heavy pruning. This is a good time to tidy up plants and to remove suckers and watersprouts.
In mid- to late fall, make only thinning cuts. Heading cuts made late in the season can stimulate soft new growth that is easily damaged in fall freezes. Don’t prune plants during the period when their leaves are falling.
Late winter is the traditional time to prune dormant plants; leaves have dropped, and it’s easy to see plant form. Winter pruning stimulates growth, but the results are delayed until spring. This is a good time to prune landscape trees as well as apples and other fruit trees, brambles, grapes, roses, and shrubs that form flowers on the current year’s wood.
An espalier is a fruit tree or shrub trained to grow flat, usually against a wall, supported on a strong lattice, trellis, or wire fence. Wire is easiest and usually the most practical support for fruit trees.
Classic espalier patterns include fan training and a Belgian fence, which has a geometric pattern of crossing branches. In addition to the usual ones, you can also establish an informal pattern to suit a more naturalistic garden and plants that don’t form spurs. Train the branches (or at least the tips) of informal, fruit-bearing espaliers at an angle of at least 30 degrees above the horizontal to encourage branch vigor and flower production.
Plant your young tree about 1 foot away from the framework to allow room for the trunk to expand as it grows. Space it midway between two posts.
Start careful pruning early in the life of the tree, and continue it at regular intervals during the whole life of the espalier. As an espalier gets older, less and less pruning is needed. It may take several years of training to “finish” a pattern.
Balancing the pattern: In general, strive for a balanced pattern by encouraging weaker branches and discouraging branches that are too vigorous. Do this by pruning the strong branches shorter and allowing weaker ones to grow longer. Rub off side buds on the stronger branches right away, but leave the buds on weaker branches. Tie the more vigorous branches frequently and closely to the supports. Leave weaker branches growing freely a little while longer. Remove some leaves from the stronger ones, and remove all fruit from the weaker ones.
Maintenance training: Early in summer, pinch back each lateral branch as soon as it has made three or four leaves. Also pinch back terminal shoots when they have made a few inches of growth. If a lot of leafy growth occurs as summer progresses, nip out a few shoots entirely.
Throughout the growing season, remove branches that are not growing in the right direction or that are growing out from the framework. Don’t let fruiting spurs develop more closely than 5 to 7 inches apart. When very old spurs bear repeatedly, either prune the spur or thin out the fruit in early summer.
During the dormant season (late winter is better in the North), cut back every lateral branch to two or three buds. If laterals are close together, remove some to prevent a bunchy look. At the same time, shorten every vertical shoot. If there has been moderate growth (from 4 to 8 inches), just cut back each tip to a healthy-looking side bud. If growth has been vigorous (more than 9 inches), remove up to two-thirds of the shoot. Also cut back the leader if it is growing above the desired height.
Prune evergreen espaliers throughout the growing season. Start early in spring just before growth begins. Remove crowding branches entirely. Cut back terminal shoots to within a few inches of the previous year’s wood.
Choose pruning tools that cut cleanly and easily. Keep the cutting edges sharp. You’ll probably need only three pruning tools: pruning shears for stems and twigs, lopping shears for branches that are finger-size and larger, and a pruning saw for larger branches and crowded areas.
Pruning shears are available in two types. Anvil pruners cut with a sharp blade that closes against a metal plate, or anvil; bypass pruners work like scissors. A leather holster for your shears is a wise investment.
Lopping shears have long handles that extend your reach and give you leverage for more cutting strength. A small rubber shock absorber is a welcome addition on some models. Folding pruning saws fit nicely into a back pocket, but you’ll have more blade choices if you buy a nonfolding saw. One feature to look for is a blade that cuts on both the push and the pull strokes, making it easier to cut in close quarters. Pole pruners can be used for overhead work. The pruning head can consist of either a saw or a cord-operated hook-type shear, or a combination of the two. You may find hedge shears useful for keeping formal hedges neat.
Ornamental cherry, plum, almond. Deciduous or evergreen spring-flowering trees or shrubs.
Description: Many members of this genus produce edible fruit; you’ll find more information in the Cherry, Peach, and Plum entries.
Prunus cerasifera, myrobalan plum, is a deciduous shrub or small tree with a rounded, spreading habit and a mature height of 15 to 25 feet. Pale to deep pink flowers precede the leaves, which are purple on most cultivars. Zones 4–8.
P. glandulosa, dwarf flowering almond, is a diminutive shrub of 3 to 5 feet with slender twigs and a delicate, open branching habit. Single or double, pink or white flowers appear before the leaves in early to mid-spring. Zones 4–8.
P. laurocerasus, cherry laurel, is an evergreen shrub that bears white flowers in early to mid-spring. Leaves are shiny and leathery; fruits are black. Zones 6–8.
P. serrulata, Japanese flowering cherry, grows 20 to 25 feet tall and is vase-shaped; single or double blooms are white to pink. Zones 5–7.
P. subhirtella, Higan cherry, grows 25 feet tall and bears pale to deep pink single or double flowers before leaves appear. Zones 5–9.
How to grow: Except for the cherry-laurels (which prefer shade), most species need full sun and well-drained soil. Protect the thin bark from lawn mower injuries. Prune after flowering. P. cerasifera and P. laurocerasus have been identified as invasive in some states.
Landscape uses: Most tree cherries make fine focal points or groupings in a sunny area. Cherry-laurels work well in shade individually or grouped. Most Prunus attract birds.
See Squash
See Echinacea
Pyracantha, firethorn. Spring-blooming evergreen or semievergreen shrubs.
Description: Pyracantha coccinea, scarlet firethorn, is an upright, irregular, spiny shrub reaching 15 feet tall. It has oval, 1- to 1½-inch, dark to medium green leaves, clusters of small white flowers in spring, and showy orange-red berries that persist through fall. Zones 6–8.
How to grow: Provide full sun and good drainage. In southern climates, site firethorns where air circulation will be good; in the North, site them out of the winter wind. Once established, they need little supplemental water. Prune diligently to remove watersprouts and suckers and to maintain shape. A neglected pyracantha is soon out of control. Once overgrown, it is difficult to coax back to size without some awkward pruning cuts.
Pyracantha is susceptible to many of the same diseases that trouble apples and pears, including scab and fire blight. Avoid planting near fruit trees to prevent shared problems.
Landscape uses: Scarlet firethorn makes an attractive espalier—its flowers and berries are set off by a wall or trellis. You can also use firethorn as a hedge; it makes a nearly impenetrable barrier. Plant it to attract berry-eating birds in winter. In the Pacific Northwest, plants may become invasive because birds eat and spread the seeds. Although pyracantha is an attractive landscape plant, its disease susceptibility and tendency to spread aggressively via seedlings can make it a poor choice for adding to a landscape. If you’re installing new plants, consider native alternatives such as viburnums or hollies (Ilex spp.) instead.
Pear. Spring-flowering deciduous trees.
Description: Members of this genus produce edible fruit; you’ll find more information in the Pear entry.
Pyrus calleryana, Callery pear, is familiar in city landscapes because its cultivar ‘Bradford’ has been widely planted as a street tree. This popular cultivar, which has escaped cultivation and is considered invasive in some states because birds eat and spread the seeds, is pyramidal when young and rounded with maturity, with a dense crown. It attains a mature height in the range of 25 to 40 feet. Its winter buds are a woolly buff color, and its white, malodorous flowers appear in early to mid-spring before the leaves, which are glossy dark green. Spectacular fall leaf colors of reds, russets, oranges, and yellow are reliable most years, especially in the North. Small (½-inch), round pears appear in fall. Zones 5–8.
How to grow: Provide full sun and good drainage. Pears can have serious problems with fire blight, a bacterial disease, during wet summers. Watch for branches forming fire blight’s distinctive “shepherd’s crooks” at their tips following warm, wet weather during periods of rapid growth. ‘Bradford’ shows good resistance to fire blight, but like many other Callery pears, it has naturally narrow (and therefore weak) crotch angles that often break under the weight of mature (perhaps snow-laden) branches. Instead of planting ‘Bradford’, choose other flowering trees such as serviceberry (Amelanchier spp.), white redbud (Cercis cvs.), and Carolina silverbell (Halesia carolina).
Landscape uses: Callery pears look nice when massed or as a focal point, especially for an early splash of white flowers. Their tolerance of urban conditions, combined with abundant flowers, attractive foliage, and availability of small to midsize cultivars, makes them a common sight (some would say too common) along the sidewalks of many American cities.
