Buds drop off before they open.
CAUSE: Shock from change of environment.
REMEDY: Find a hospitable spot for your exacum and give the plant regular water and a balanced plant food. New buds and blossoms should appear within 3 weeks.
Leaves specked with yellow; webby material on leaf undersides.
CAUSE: Spider mites.
REMEDY: See page 274 for details on identifying and treating this pest. Pinch off and dispose of all affected branches. Clean plant with a spray of water, isolate it, and mist three times daily. If problem persists, dispose of the plant.
Leaves are pale and crinkled.
CAUSE: Aphids.
REMEDY: Isolate plant and treat with insecticidal soap as described on page 278. Repeat after 5 days.
Plant wilts despite watering and gradually collapses.
CAUSE: Root rot.
REMEDY: This is not unusual with this plant. Discard the plant and thoroughly clean the container before using it to grow another houseplant.
FAMILY: RUBIACEAE ORIGIN: CHINA
FRAGRANT, SNOWY WHITE BLOSSOMS framed by glossy, dark green foliage make gardenia a popular gift plant. Perhaps you crave gardenia’s intoxicating scent so much that you buy one for yourself, determined to grow this romantic little shrub near a sunny south window. Several varieties grow only 24 in/60 cm, and these dwarfs are often seen in stores around Easter, loaded with blossoms. Unable to resist, you snap one up.
Gardenia (Gardenia jasminoides)
In subsequent seasons, you will find that gardenia is not the easiest plant to bring into bloom, though plants that are happy with their situation will often bloom in late spring and again in the fall. In between, they enjoy spending the summer outdoors in a shady spot. Thoroughly clean plants before bringing them back indoors to prevent possible pest problems. In winter, keep the leaves lustrous by polishing them every 6 weeks with a soft cloth that has been lightly sprinkled with vegetable oil.
Light: Bright light at least 4 hours daily, but not strong midday sun.
Temperature: Cool (60°F/16°C) nights and warmer (75°F/24°C) days promote strong flowering.
Fertilizer: Feed plant every 2 weeks with a balanced houseplant fertilizer that contains micronutrients, especially iron, or use a slow-release azalea fertilizer sprinkled into the pot.
Water: Keep soil lightly moist, but do not overwater. Gardenias love high humidity, which is best provided with a humidifier or tray of damp pebbles.
Soil: An acidic mix of 2 parts potting soil and 1 part peat moss.
Repotting: Repot young plants annually in late winter until the roots fill 8 in/20 cm pots. After the root mass reaches this size, repot every 2 years to refresh the soil.
Longevity: Indoors, 10 years, more or less. Outdoors, plants live for decades.
Propagation: Root stem cuttings taken in spring or early summer. Rooting powder and high humidity are essential to success.
Selections: ‘White Gem’ is the most popular upright gardenia to grow in containers. Even when fully grown, it stands only 24 in/60 cm tall. Another dwarf variety, ‘Radicans’, has a semi-prostrate posture, which makes it a good plant for training as bonsai. A taller variety, ‘Veitchii’, often called everblooming gardenia, is a good choice for airy sunrooms or other large spaces.
Display tips: When your gardenia blooms, place it on a tabletop so the flowers will give off their perfume at nose level.
Leaves turn yellow though leaf veins remain green.
CAUSE: Nutritional disorder associated with high soil pH and low temperatures.
REMEDY: Move plant to a place where temperatures are above 70°F/21°C, and fertilize it with an azalea fertilizer that includes iron, magnesium, and sulfur.
Entire leaves turn yellow.
CAUSE: Overwatering.
REMEDY: Check drainage holes to make sure they are free of debris. Allow soil to dry slightly between waterings, so that the top inch of soil feels dry to the touch.
Flower buds fall off before they open.
CAUSE: Too little light, too much or too little water, high temperatures, or very dry air.
REMEDY: As soon as you see buds on your gardenia, spoil the plant by giving it perfect growing conditions. Situate it in a spot where it will get bright natural light for half the day, followed by cool nighttime temperatures. Wait until the blooms open to gently move the plant to a spot where you can easily enjoy its fragrance.
Leaves are pale with webby material on leaf undersides.
CAUSE: Spider mites.
REMEDY: Isolate plant, and spray it with water followed by insecticidal soap. Repeat weekly until the infestation is controlled. It is best to take preventive measures by cleaning plant with plenty of warm water once a month. When bringing a gardenia indoors after a summer outside, spray it with insecticidal soap as a safety precaution.
White cottony masses on leaves and stems.
CAUSE: Mealybug.
REMEDY: Isolate plant and remove mealybugs with a cotton swab dipped in alcohol. Repeat weekly until mealybugs are controlled. See page 272 for additional information about this pest.
IN ADDITION TO THE GERANIUMS OFTEN GROWN OUTDOORS in the summer garden, there are several types that make outstanding houseplants. Historically, geraniums have been grown indoors longer than they have been enjoyed in the garden, and they are such interesting and rewarding houseplants that they definitely deserve wider use. The three types that make the best houseplants include fancy-leafed zonal geraniums, scented geraniums, and regal or Martha Washington geraniums, each of which is profiled individually in the following pages.
Bold and bright, geraniums are excellent candidates for summering outdoors, then bringing in to enjoy throughout winter indoors.
The geranium common name will probably persist forever, but more than 200 years ago these plants were reclassified as Pelargonium, a genus within the Geraniaceae family. The pelargonium name caught on in Europe, but North America has stuck by its use of the word geranium. In the interest of accuracy, they will be called pelargoniums here. However, from a practical point of view, you should be prepared to use the names geranium and pelargonium interchangeably when shopping for plants.
You will probably need to seek out houseplant-worthy geraniums. Many strains that were popular parlor plants in Victorian times have been preserved and propagated by specialty growers; they are available by mail if you can’t find them locally. There also are modern varieties with much to offer, for example hybrids that combine the exotic leaf color of zonals with deliciously scented foliage borrowed from scented types, and regals that produce huge flowers in late winter.
Indeed, because pelargoniums have been so extensively hybridized, the dividing lines between the three types have become blurred. Once upon a time, zonals were grown for color, scenteds for fragrance, and regals for off-season bloom. These days, you may be able to have it all in one plant. Still, you do need to know whether your plant should be handled as a zonal, scented, or regal type. This is important, because the three types vary in their seasonality, water requirements, and a few other cultural details. Use the chart to help identify which type of pelargonium you have, or wish to have. Then turn to the appropriate profile page for detailed information on how to bring out its best talents as a house-plant. The Troubleshooting section explores possible problems, which all types of pelargonium have in common.
Old florets shrivel before all the buds in the cluster open.
CAUSE: This is normal for many geraniums.
REMEDY: Use a small pair of scissors to clip out the withered florets. When most of the flowers in the cluster have peaked, clip off the blossom-bearing stem where it rises from the main branch.
New leaves are small; older leaves turn yellow.
CAUSE: Insufficient fertilizer.
REMEDY: Increase feeding by adding a half ration of soluble plant food to the water at each watering, or by feeding at the rate recommended on the fertilizer package once a week.
Plants develop lush leaves but no flowers.
CAUSE: Too much fertilizer.
REMEDY: Reduce the amount or frequency of plant food. If you are using a balanced or high-nitrogen plant food, switch to high-phosphorous fertilizer.
Old leaves turn yellow, then brown.
CAUSE: This is a normal growth pattern, or plant may be reacting to reduced light.
REMEDY: When grooming plants, routinely remove old leaves that have begun to yellow. Many older leaves may turn yellow and drop if you do not prune back plants before bringing them indoors after allowing them to spend the summer on a porch or patio.
Buds have small holes in them and fail to open.
CAUSE: Small caterpillars called budworms, common outdoors but rare indoors.
REMEDY: Clip off affected buds and dispose of them. Clean plants with a fine spray of water. New buds that emerge 2 to 3 weeks later should be free of this pest.
Rusty brown spots on leaves; affected leaves turn brown and drop off.
CAUSE: Bacterial leaf spot.
REMEDY: Trim off affected leaves if there are only a few of them. Prune off affected branches. Repot plant in fresh soil, using a clean container. If problem persists, dispose of plant and start over with a disease-free specimen.
Leaves dry and parched; faint webbing on leaf undersides.
CAUSE: Spider mites.
REMEDY: Isolate plant and attempt to control the mites as described on page 274. Discard badly affected plants, or prune them back severely and hope for the best.
Regal geraniums are often sold as winter-flowering houseplants.
In the following pages, the three best types of pelargonium to grow indoors are described in detail. They are listed by botanical name, which are often somewhat generic hybrids. In fact, the parentage of some varieties is so complex that species names have been dropped altogether! Name or no name, use this chart to identify what type of geranium you have, and then turn to the appropriate plant profile to get to know your pelargonium better.
Regal geraniums remain old favorites for the garden and as houseplants.
FAMILY: GERANIACEAE ORIGIN: SOUTH AFRICA
EACH LEAF OF A SCENTED GERANIUM is laden with special cells that explode with fragrance at the slightest touch. Scents range from citrus to chocolate to rose. The apple-scented species (P. odoratissimum) and old-fashioned rose (P. graveolens) are large, vigorous plants, but many selections are much daintier in size. Nutmeg (P. × fragrans) is often recommended for beginners, and most citrus-scented pelargoniums are small plants that fit easily on a sunny windowsill. The leaves of most scented strains are crinkled and more finely cut than those of the zonal types. A few are valued as much for their flowers as for their fragrance, but scented geraniums are usually light bloomers.
Scented geranium hybrid (Pelargonium ‘Atomic Snowflake’)
Most scented-leaf pelargoniums never become dormant, though they are willing to rest in winter in a cool basement. If you try this method of off-season care, keep the roots quite dry, watering only enough to keep the plants from shriveling. Otherwise, keep your plant in good light year-round, but push it to produce new growth only in spring and summer.
Light: Bright light from a south or west window. Many people shift plants outdoors in summer, and allow them to become semidormant in winter.
Temperature: Cool to average room temperatures (60–75°F/16–24°C).
Fertilizer: From spring through fall, feed plants every 2 weeks with a balanced, all-purpose houseplant food that includes micronutrients. In winter, do not feed.
Water: Allow soil to dry to within .5 in/1.25 cm of the surface between waterings in spring and summer. Water much less in winter, but do not allow roots to dry out completely.
Soil: Any good potting soil that drains well.
Repotting: Annually in spring.
Longevity: 3 to 4 years for individual plants, which can be kept indefinitely when propagated from rooted stem cuttings.
Propagation: Soon after new growth appears in spring, take 3 in/7.5 cm-long stem tip cuttings and set them to root as described on page 299.
Selections: Revered old varieties include ‘Mrs. Taylor’, with red flowers and pungent lemony leaves. ‘Old Spice’ smells like its namesake fragrance.
Display tips: Don’t be reluctant to pinch and sniff leaves of scented geraniums. When pruning, save leaves to dry and use in potpourri.
FAMILY: GERANIACEAE ORIGIN: SOUTH AFRICA
REGAL GERANIUMS ARE OFTEN CALLED Martha Washingtons, the name of a once-famous cultivar. Regals are often sold as winter-flowering houseplants, and they are commonly grown outdoors in climates where nights stay cool through summer, such as the West Coast. The plants are not at all difficult to keep alive, but it can be challenging to get them to rebloom well. The key is to follow a special seasonal rhythm of care. In early summer after flowering stops, cut plants back to about 4 in/10 cm, repot them, and allow them to rest inside for a month. Give them enough water to keep them alive, but wait until midsummer to begin feeding them. When nights cool to below 55°F/13°C in fall, place plants outdoors for at least 6 weeks. Plants use this cool conditioning period to develop buds, which may not show until midwinter. Look for large, dramatic flower clusters in February or March.
Regal geranium (Pelargonium × domesticum)
FAMILY: GERANIACEAE ORIGIN: SOUTH AFRICA
COMMON GARDEN GERANIUMS are zonal types, but there are much showier varieties that make beautiful and rewarding houseplants. These special pelargoniums have graced sunny windows for many decades. Leaf variegation often appears in halo patterns, with a red or bronze halo ringing the leaf’s center, and white bands or splashes near the margin. Varieties with mostly green leaves are valued for their flowers, which often are produced year-round when plants are pruned periodically to force out new growth.
Do look into these wonderful, collectible, fancy-leafed pelargoniums, but in the meantime you can also coax bedding geraniums, which also are zonal types, into bloom. In late summer, gradually move outdoor-grown plants to shadier quarters to acclimate them to reduced light. Even when acclimated, zonal geraniums often shed half their leaves when they are moved indoors, so don’t be alarmed. Clean up after them, and prune off up to half of the long, brittle branches. Blooming should resume after 3 to 5 weeks.
Zonal geranium (Pelargonium × hortorum)
Light: Bright light from a south or west window.
Temperature: Cool to average room temperatures (60–75°F/16–24°C).
Fertilizer: Feed plants every 2 weeks with a balanced houseplant food that includes micronutrients.
Water: Allow soil to dry to within 1 in/2.5 cm of the surface between waterings, but do not allow the roots to become so dry that the plants wilt.
Soil: Any good potting soil that drains well; some people add a handful of sand to standard potting soil to improve drainage when potting geraniums.
Repotting: Annually in spring to provide a clean pot and fresh potting soil.
Longevity: 3 years, or indefinitely when propagated from rooted stem cuttings.
Propagation: When new growth emerges in spring, take 3–4 in/7.5–10 cm-long stem tip cuttings and root them as described on page 299. Some varieties are much easier to propagate than others.
Selections: Once-popular dwarf varieties with variegated leaves, such as ‘Skies of Italy’, are well worth seeking out. In addition, some zonals have scented leaves, including pink-flowered ‘Roger’s Delight’, ‘Prince Rupert Variegated’, and many others.
Display tips: Grow geraniums in good-quality terra-cotta pots that feature simple relief patterns. Geraniums are among the cheeriest plants you can grow in an office that includes a spot of bright sunlight.
FAMILY: MALVACEAE ORIGIN: CHINA
THE STATE FLOWER OF HAWAII, hibiscus bears the largest blossoms that can be produced by an indoor plant. Some measure more than 8 in/20 cm across, and all feature crepe-paper-textured petals that flare around a prominent yellow stamen. Individual blossoms last only 2 to 3 days, but well-adjusted plants often bloom intermittently from late spring to late fall.
Hibiscus plants need warmth, so they are best grown near a south or west window. If possible, move them outdoors in summer to a place where they will receive partial sun. Be sure to bring them back indoors before night temperatures fall to 50–55°F/10–13°C. You can control the size of your hibiscus by pruning the plant lightly in early summer and more aggressively in fall. Hibiscus blooms form on the tips of new branches, which emerge from just below where older branches are tipped back.
Hibiscus (Hibiscus rosa-sinensis)
Light: Bright, including some direct sun.
Temperature: Warm (65–85°F/18–29°C).
Fertilizer: From spring through summer, feed every 2 weeks with a balanced liquid fertilizer. In winter, feed monthly. Alternatively, fertilize twice yearly with a high-nitrogen, controlled-release fertilizer. Special hibiscus fertilizer has an analysis of 18-5-23.
Water: In warm weather, water as often as needed to keep soil lightly moist at all times. In winter, allow soil to dry to within 1 in/2.5 cm of surface between waterings.
Soil: A light-textured potting soil that contains perlite and peat.
Repotting: Annually in fall, prune back stems by one-third, and also trim off about one-fourth of roots before repotting.
Longevity: 5 to 10 years for most hybrids.
Propagation: Many hibiscus can be propagated by rooting 6 in/ 15 cm-long stem tip cuttings as described on page 299. Many hibiscus are grafted onto special rootstocks, so rooted cuttings may not show the vigor of their parent.
Selections: There are dozens of named varieties in shades of pink, blue, red, and yellow, with many bicolors. ‘Dragon’s Breath’ features bold red, 8 in/20 cm blossoms with white swirls in the centers. ‘The Path’ is bold yellow with magenta centers.
Display tips: Grow plants in pots that can be slipped inside larger planters equipped with wheels so they are easy to move outdoors in summer.
Buds drop off soon after they form.
CAUSE: Environmental stress or weak cultivar.
REMEDY: Any type of stress that strikes when buds are swelling can cause plants to give up their will to bloom. Water attentively after buds appear, and avoid moving bud-bearing plants unnecessarily. Varieties that produce large, double flowers are more likely to drop buds than those that bear single blossoms.
Leaves turn yellow and drop off.
CAUSE: Normal in fall, but excessive leaf drop can be caused by sudden reduction in light.
REMEDY: Plants that are grown outdoors in summer — and even those kept indoors year-round — often shed some of their leaves when returned to comparatively dim indoor rooms. To keep shedding to a minimum, gradually accustom plants to less light.
Leaves appear parched, with pale yellow specks.
CAUSE: Spider mites.
REMEDY: Prevent this problem by washing off leaf undersides with plenty of water once a month. See page 276 for details on identifying this pest. If spider mites are present, isolate plant, prune off badly infested branches, and spray plant daily with water. Use insecticidal soap if problem persists.
Leaves small and misshapen.
CAUSE: Too much phosphorous in fertilizer.
REMEDY: Some hibiscus are sensitive to high amounts of phosphorous (the middle number in a fertilizer’s analysis). Leach pots as described on page 263 and switch to a low-phosphorous fertilizer.
FAMILY: OLEACEAE ORIGIN: CHINA
A VINING MEMBER OF THE OLIVE FAMILY, jasmine is grown for its twining stems, glossy green leaves, and fragrant flowers that appear in winter. This vine can be grown outdoors through Zone 8, but it is not difficult to keep as a houseplant provided you follow its natural growth rhythms. In summer, give it a very sunny spot where warmth and light will encourage vigorous growth. Move it outdoors in fall to expose it to 6 weeks of cool temperatures (40–60°F/4–16°C). Jasmine uses this cool period to set buds, which will remain very small until late winter. Plants typically bloom in February, when the clusters of pink buds open into starry white flowers. Fragrance is often strongest at night.
After the flowers fade, prune back the plants and allow them to rest for a month or more. Pruning is needed to control this plant’s size, which can easily exceed 5 ft/1.5 m. With hard pruning in spring and occasional trimming during the summer, jasmine will grow into a graceful vine that needs little help twining around whatever support you provide.
Jasmine (Jasminum polyanthum)
Light: From late spring through fall, bright light, including 4 hours of direct sun. In winter, moderate to bright light.
Temperature: In fall, cool outdoor temperatures (40–60°F/4–16°C). In winter, average room temperatures (65–75°F/18–24°C). From late spring through summer, warm outdoor temperatures (70–85°F/21–29°C).
Fertilizer: From spring through fall, feed every 2 weeks with a high-phosphorous plant food. In winter, feed monthly.
Water: From early summer through fall, keep lightly moist, allowing soil to dry to within .5 in/1.25 cm of the surface between waterings. In fall, water less. In late winter and spring, keep plant slightly dry during this resting period.
Soil: Any good potting soil.
Repotting: Annually in spring after aggressive pruning. Install some type of support when repotting plant.
Longevity: Many years, or indefinitely when propagated from stem tip cuttings.
Propagation: Take 4 in/10 cm stem tip cuttings in early summer and root them as described on page 299.
Selections: In addition to Chinese jasmine, Arabian jasmine (J. sambac) features stronger fragrance, but is more difficult to grow since it requires very warm, humid conditions.
Display tips: Train plant to twine around a hoop or up a slender post. Keep it in a bright window when it comes into bloom in late winter.
Plant does not bloom.
CAUSE: Lack of cool conditioning in the fall.
REMEDY: Jasmine sets its buds in the fall, and cool conditions are needed to ensure good budset. Keep plant outdoors for 6 weeks when the weather cools in the fall. If you have no place to condition plant outdoors, keep it in your coolest room in October and November.
White cottony masses on leaves and stems.
CAUSE: Mealybugs.
REMEDY: Mealybugs love this plant. If they appear in late winter, after the plant has bloomed, severely prune it before removing survivors by hand using tweezers or a cotton swab dipped in alcohol. If the problem persists, spray plant with insecticidal soap. When plant is moved outdoors in summer, natural predators may bring mealybugs under control.
Leaves turn yellow and drop.
CAUSE: Too much water, insufficient light, or needs pruning.
REMEDY: Water only enough to keep soil lightly moist. Jasmine needs strong light, and will languish in low light conditions. Plants that are not pruned hard in spring often become bare at the base as they shed old leaves.
New growth slow; few new leaves.
CAUSE: Insufficient light.
REMEDY: Place plant in a very sunny spot in spring and summer, or move it outdoors to partial shade.
IF YOU LOVE BEAUTIFUL FLOWERING HOUSEPLANTS, sooner or later you will want to grow an orchid. Or several! It takes but a little success with these interesting plants to want more, and despite their finicky reputation, many orchids are easy to grow. In the next few pages, you will be introduced to the five types of orchids that are widely recommended for beginners: cattleyas or corsage orchids (Cattleya); “dens,” sometimes called spray orchids (Dendrobium); dancing ladies (Oncidium); lady’s slippers (Paphiolpedilum); and moth orchids (Phalaenopsis). Orchids can be costly, so it pays to learn a little about them before buying your first plants.
By selecting the right varieties, anyone can grow at least a few orchids successfully.
The Orchidaceae family is extremely large and diverse, with 28,000 species occurring in a wide range of environments, from tropical rain forests to dry alpine rock outcroppings. Orchids that adapt easily to homes and offices are mostly forest-dwellers that live in the wild on tree limbs and rocks.
Over the last 200 years — and especially in the late 1800s — orchid hunters took millions of orchids from their native habitats and shipped them to wealthy patrons. But orchids are no longer greenhouse flowers only for the rich. New methods of propagation, including tissue culture, in which thousands of plantlets can be grown in test tubes from a small piece of parent plant, and seeds sprouted in flasks under laboratory conditions, have made orchids much more affordable, while helping to prevent further pilfering of dwindling natural populations. However, because even tissue-cultured orchids do not begin blooming until they are 5 to 6 years old, orchids remain somewhat costly. And it is still true that some orchids, for example those that produce the huge blossoms used in corsages, are best grown in a greenhouse where light, temperature, and humidity can be tailored to meet the preferences of plants rather than people.
Botanically, orchids are among the most highly evolved flowers on Earth. In orchids, the male and female flower parts are fused into one anatomical organ, called the column. For pollination to take place, the right insect must be drawn into the flower and then crawl about a bit, so orchid flowers have evolved with this specific purpose in mind. When you admire the intricate structures and markings in an orchid blossom, you are seeing the stage upon which a tricky pollination play will be performed.
Orchids do produce seeds, but they are extremely tiny and require the presence of helpful fungi before they can germinate and grow. In modern times, it has been learned that orchid seeds can be germinated successfully in agar jelly, and this has led to a boom in orchid hybridization. In the world of orchids, it is not only possible to cross-breed different species, but genera as well.
Light: Most orchids grow best in bright, indirect light from a south window, but lady’s slippers and moth orchids need less. They often thrive in an east or west window, or when grown under fluorescent lights. To help you choose the best plants for your situation, the chart compares the light and temperature preferences of the easiest orchids. Outdoors, place orchids in filtered shade where they will receive little, if any, direct sun, and also be shielded from prevailing wind.
Lady’s slipper orchids (Paphiopedilum species and hybrids) need less light than other species, and each bloom includes a prominent pouch, or slipper.
The growth habits of orchids are as variable as the flowers. Left to right: hybrid forms of Cattleya, Dendrobium, Phalaenopsis, Oncidium, Paphiopedilum.
Temperature: The orchids presented here are appropriate for a range of possible growing conditions. The one thing all orchids have in common is a need for a 15–20°F/8–10°C difference between day and night temperatures. The plant profiles suggest the best range for each type of orchid, which can be cool (60°F/16°C nights and 75°F/24°C days), intermediate (65°F/18°C nights and 80°F/27°C days), and warm (70°F/21°C nights and 85°F/29°C days). There is some leeway here, but choosing an appropriate orchid for the place you have to grow it is crucial if you want a healthy, heavy-flowering plant.
Orchids benefit from being moved outdoors in summer, particularly those that like warm temperatures. Check the preferred temperature range for your plants, and wait until weather conditions are perfect to gradually accustom them to increased light. You may want to keep plants indoors that show signs of imminent bloom. Slugs, snails, and random insects find the buds irresistible. If you live in a hot climate, keep cool-natured orchids indoors through the summer. (See page 291 for more details on moving plants outdoors in summer and bringing them back inside in the fall.)
Soil: Potting soil for orchids is not potting soil at all, but rather a mixture of coarsely chopped fir bark or redwood bark, with small amounts of peat moss, perlite, or vermiculite mixed in. This mixture (or something similar; there are many variations) drains quickly and there is room between the particles for air to reach the orchid’s roots. Orchid mix decomposes slowly over a period of 2 years, which is the usual repotting interval for orchids. Large garden centers stock orchid mix, or it can be purchased from orchid growers or specialty supply companies (see Resources). Orchid mix is also good for potting most bromeliads.
The intricate markings in orchid flowers are intended to lure pollinating insects. In the wild, many orchids require the work of obscure native bees that are as rare as the orchids they pollinate.
Fertilizer: Orchids are slow growers by nature, but they need regular feeding, since their potting medium offers meager nutrients. Many growers use the phrase “weekly-weakly” to describe their feeding practices, which consists of mixing a high-nitrogen houseplant fertilizer, such as those recommended for foliage plants, at one-fourth the normal strength, and giving it to plants about once a week. When you see signs that your plant is developing flowers, you might switch to a dilute high-phosphorous fertilizer for a few weeks. If plants are moved outdoors in summer, you may want to increase the rate of fertilizer to one-half the normal strength to compensate for the nutrients that are washed away by frequent watering. Some spray orchids shed their leaves and rest in winter. Do not feed resting plants. The plant profiles make specific suggestions for fertilizing different types of orchids.
Orchid breeders have developed complex hybrids that often involve parents from different genera, which is an unusual accomplishment in the world of plants.
Water: The watering needs of orchids vary with their origins. Those that naturally grow in tree crotches or on rocks need to dry out between waterings, while ground-dwelling species, such as most lady’s slippers, need a steady supply of moisture. Many orchids have swollen stems, called pseudobulbs, which function as water-holding organs. Like succulent plants, orchids with pseudo-bulbs can gather and store moisture until it is needed. The plant profiles give specific watering instructions, but when in doubt, err on the dry side. Orchids are easily damaged by too much water.
Many orchids bloom on arching stems, which makes them even more graceful and beautiful.
Orchids are also sensitive to salts that accumulate in the growing medium, so they should be flushed monthly in summer. Thoroughly water plants, allow excess water to drain away, and then repeat.
The orchids described here need moderate humidity, in the 50 percent range. Mist plants often with clean rainwater or distilled water, which do not leave salt deposits on the leaves like tap water sometimes does. Mist lightly yet often, and never so heavily that water accumulates in the crown of the plant. Setting plants on a tray filled with damp pebbles increases humidity as well, as does placing open bowls of water near the plants. If you have a number of plants to satisfy that need moderate humidity, running a humidifier is an easy answer. See page 266 for more ways to increase humidity for houseplants.
Dancing ladies orchids (Oncidium) are beloved for the number of small blossoms they carry at any one time.
Repotting: Most orchids need repotting every 2 years, but flowering is best when the plants are slightly rootbound. The main reason to repot a plant is to provide it with fresh potting medium, since orchid potting mix decomposes over time. The best time to repot an orchid is summer, or whenever the plant appears to be in a very active period of growth.
How you repot (and propagate) orchids depends on their growth habit. But don’t assume that you should divide a plant that simply needs repotting. Orchids usually grow and bloom best when they are divided infrequently, and large plants are easier to care for than smaller ones. Still, understanding the growth habit of your plant is basic to proper repotting. Two terms often are used to describe the growing habits of orchids.
• Monopodial, or upright orchids, develop stems that emerge from a crown, or “foot.” When the plant is mature, flower spikes emerge from the stem, usually in the midsection between the leaves. Lady’s slippers and moth orchids are usually monopodial.
• Sympodial, or creeping orchids, develop a shallow creeping rhizome. The tip of the rhizome sends out a green shoot that eventually flowers. Cattleyas, dendrobiums, and oncidiums are sympodial.
By the time you need to repot your orchid, you will probably know it well enough to recognize its growth habit.
Thoroughly soak roots before repotting, which makes the roots less brittle and prone to breakage. You may need a screwdriver or table knife to pry an orchid out of a tight pot; sometimes it is necessary to shatter a clay pot to free a rootbound orchid. Examine the roots, use scissors or pruning shears that have been sterilized in boiling water to clip off any that are black or mushy, and tease out the old potting mix. Then rinse the roots with lukewarm water to remove trapped bits of old potting mix. With creeping species that form pseudobulbs, cut off the oldest pseudobulb, with roots attached, and dispose of it.
Many fancy corsage orchids (Cattelya) are not difficult to grow if you can provide them with plenty of warmth.
Place broken crockery or coarse gravel in the bottom of a new or thoroughly clean pot, and fill it two-thirds full with damp orchid potting mix. With sympodial orchids, set the groomed plant in the pot a little off center, so that the oldest pseudobulb is close to the edge but there is at least 1 in/2.5 cm of space between the newest growing tip and the edge of the pot. Add more potting mixture, tamping it in with a stick. When you’re finished, the rhizome should still be visible at the surface, about .5 in/1.25 cm below the edge of the pot. If necessary, tie the plant to a slender stake to hold it upright. Orchid-supply companies sell special wires, called rhizome clips, that hold plants in position by anchoring them to the edge of the pot.
After grooming a monopodial orchid, place it in the center of a prepared pot, and repot it at the same depth it grew in its previous container. With all orchids, it is important to tamp the pot well to help settle the planting medium firmly around the roots. Tap the pot on a hard surface several times, and gently press it down from the top. The medium should be sufficiently firm that the plant does not fall out when you hold the container sideways.
Be careful not to overwater a newly repotted orchid. Allowing it a dry rest for a few days helps it seal off damaged roots. Wait a month after repotting to resume feeding your orchid.
Propagating: Orchids will let you know when they need to be propagated, and a close look at the plant will suggest how it should be done. Dendrobiums produce aerial roots, so you can cut off the top of the plant, with roots attached, and simply pot it up. Cattleyas, dancing ladies, and other orchids that produce pseudobulbs can be cut into clusters of three during routine repotting. Lady’s slippers form clumps, which can be divided every 4 to 6 years. Moth orchids and dendrobiums often develop small plantlets, called keikis, on the flower stem close to the parent plant. When the keikis have three leaves and a 3 in/7.5 cm-long root, clip them off and plant them in small pot. Then baby the keiki as if it were a newly set rooted stem cutting (see page 299).
More details on propagating different types of orchids are given in the plant profiles, but these general guidelines apply:
• When propagating orchids, set the small plants in 4 in/10 cm pots so they will grow a tight, compact root system.
• Mist newly propagated plants daily for several weeks to maintain high humidity, which reduces demands on scant roots.
After propagating, orchids may not bloom for a year, or sometimes two. It is therefore wise not to propagate orchids until it is necessary, which is usually every 5 years.
Some orchids, especially dendrobiums, develop aerial roots on their stems. Cut the stem below the roots, and transplant the cutting to a small pot, kept in a warm, humid environment.
Paphiopedilum with mottled leaves, like this one, generally needs more warmth than does one with green leaves.
Small details: Take your time when shopping for orchids. It is always best to buy from a local grower so the plants will not be traumatized in shipping. Local growers also may make excellent suggestions on good beginner varieties for your area.
Instead of buying plants in full bloom, look for mature plants or those that are just beginning to produce a flower spike. Orchids that are on the verge of blooming cost a few dollars more than those that are not yet in a flowering mood. When you can “interview” prospective “or-kids” in person, look for big, plump roots and lots of them, and no bruises or soft spots on the crowns.
If you cannot buy orchids from a local grower, there are many excellent mail-order sources. The American Orchid Society (see Resources) keeps an up-to-date list at their website. Rare orchids cost much more than varieties that have been around a long time. As a beginner, it’s best to stick with proven varieties.
Growing one orchid is a satisfying experience, but orchids have a way of turning people into collectors rather quickly. Keeping a collection usually requires a greenhouse, or at least a window outfitted with a greenhouse extension. If you fall in love with growing orchids, be forewarned that other life modifications will probably follow.
Plant does not bloom.
CAUSE: Improper temperature range; too much fertilizer; not enough light.
REMEDY: Orchids must have a 10–20°F/6–9°C difference between night and day temperatures, and only enough nutrients to keep them from going hungry. Plants also may not bloom if they are younger than 5 years old or are deprived of sufficient light. Most importantly, you should choose orchids that suit the growing conditions you have to offer.
Leaf tips turn brown.
CAUSE: Overfertilization; improper watering.
REMEDY: This is a common sign of fertilizer burn in orchids. Dilute the plant food to one-fourth the rate recommended on the label. Water according to the preference of the orchid you have chosen.
White cottony masses on leaves.
CAUSE: Mealybugs.
REMEDY: This is the most serious insect pest of orchids. Practice preventive care by wiping leaves periodically with a soft, damp cloth. If a plant becomes infested, isolate it and attempt to remove mealybugs by hand, using a cotton swab dipped in alcohol. See page 273 for other methods of controlling this pest.
Flowers have small, brown, circular spots.
CAUSE: Petal blight, a fungal disease.
REMEDY: Remove affected blossoms. In the future, increase air circulation around the plants to prevent the occurrence of this problem.
Leaves turn an unusually light green color.
CAUSE: Excessive sun.
REMEDY: Move plant to a shadier spot.
Leaves show unusual crinkles and blotches; new growth is slow.
CAUSE: Virus infection; several viruses infect orchids, and they can be spread by insects or by humans when plants are handled or repotted.
REMEDY: Destroy affected plants. Sterilize scissors, knives, and other cutting instruments used in repotting by dipping them in boiling water just before using them.
Leaves show ragged holes along edges.
CAUSE: Slugs or snails.
REMEDY: When plants are placed outdoors, they become easy targets for these leaf-eating pests. Place saucers of beer beside plants. The slugs will drink it, fall in, and drown. Where these pests are truly terrible, you can buy copper tape and fasten it to the tray or table upon which orchids are kept. Slugs and snails are deterred when they come upon a copper barrier.
The five species groups described below, listed in alphabetical order by botanical name, are good orchids for beginners. Start with an orchid that accepts the light and temperature range you have to offer. Master these before moving on to orchids that are more difficult to grow.
FAMILY: ORCHIDACEAE ORIGIN: SOUTH AND CENTRAL AMERICA
THE TYPES OF ORCHIDS THAT PRODUCE large, frilly blossoms used in corsages are seldom recommended as the best types for beginners, but some people are willing to go to great lengths to grow these beautiful flowers. They are least troublesome if you live in a warm climate, because they are mostly jungle plants and crave warm temperatures and high humidity. Cattleyas also need abundant light, and you can tell if your plant is getting enough by monitoring the color of its leaves. Dark, jade green color indicates too little light, in which case the plants may refuse to bloom. Plants that are stressed by too much light show very light, yellow-green leaves. Medium green leaves with a slight yellowish cast suggests you have hit the right balance.
Corsage orchid (Cattleya hybrid)
Light: Bright year-round, including some direct morning or late-afternoon sun.
Temperature: Warm (60–85°F/16–29°C) year-round.
Fertilizer: From late spring to early fall, feed every 2 weeks, but leach pots monthly to remove excess salts. In winter, feed monthly.
Water: Allow medium to become slightly dry between thorough drenchings. Plants need more water in summer than in winter.
Soil: Orchid potting mix.
Repotting: Every 2 to 3 years, to replace potting medium that has decomposed. Add 1 in/2.5 cm or more of pebbles or other drainage material to the bottom of pot.
Longevity: Many years, or indefinitely if propagated by division.
Propagation: Divide only after plants have more than seven pseudobulbs. Separate into clumps of three or more.
Selections: If at all possible, work with a local orchid grower, because this species group is huge and varied, and plants can be quite expensive. Start with whatever orchid your expert suggests, which may be a species selection. There is tremendous variation in flower form, fragrance, and plant size. Large “standard” varieties often are easier to grow than compact miniatures, sometimes called “mini-catts.”
Display tips: Showcase your cattleya when it is in bloom by keeping it in a warm windowsill in your most-often-used room.
FAMILY: ORCHIDACEAE ORIGIN: INDIA TO AUSTRALIA
DENDROBIUMS ARE A LARGE GROUP of orchids, with more than 1,600 species known. They vary in their care, so plan to form a close personal relationship with a dendrobium. The best ones produce flowers that persist for many weeks, and some of the finest hybrids bloom in spring and again in late summer. Flower colors include yellow, red, pink, and violet, many with contrasting throats; blossoms have a light, fruity fragrance. Tall dendrobiums may grow to 18 in/45 cm or more, and often need staking to keep them upright.
Most dendrobiums like a strong seasonal life cycle consisting of warm, brightly lit summers with plenty of fertilizer and regular water, and a cooler winter when their soil is allowed to become almost dry between waterings. A brief but very dry winter rest, lasting only a month, encourages heavy flowering. When new roots appear near the base of the plant, begin feeding and watering the plant again. Many dendrobiums become deciduous plants as they reach maturity, shedding most of their leaves in winter.
Spray orchid (Dendrobium hybrid)
Light: Bright light year-round.
Temperature: In winter, cool (60°F/16°C) nights and days in the 75°F/24°C range. In summer, dendrobiums can adapt to very warm outdoor temperatures as long as there is a 15°F/8°C difference between day and night temperatures.
Fertilizer: From spring through fall, feed weekly with a balanced houseplant fertilizer diluted to one-fourth the normal strength. In winter, allow plants to rest, unfed, for a month or two.
Water: Allow soil to become almost dry between waterings. Dendrobiums can store water in their canelike stems; some species have pseudobulbs. Grow at 50 percent humidity.
Soil: Orchid potting mix.
Repotting: Every 2 to 3 years; likes to be potbound.
Longevity: Many years.
Propagation: Propagate from aerial cuttings taken from mature plants. Cut off tip just below where you see several aerial roots emerging, and pot the cutting. The parent plant will continue to grow. Plants sometimes produce keikis (see page 122).
Selections: There are hundreds, but two easy suggestions are D. loddigessi, which produces fragrant peach-colored blossoms, and ‘Wonder Nishii’, a long-blooming hybrid with sugar-scented yellow flowers marked with deep maroon.
Display tips: Tall types work well when staked and placed on the sill of a sunny window. Dwarf varieties can be grown in hanging baskets.
FAMILY: ORCHIDACEAE ORIGIN: TROPICAL AMERICA
SOME ONCIDIUM ORCHIDS bear single flowers, but most produce swarms of flowers on branched, arching stems. Most modern oncidiums are complex hybrids involving several species, and these hybrids have several advantages. They grow faster than species selections, often bloom more than once a year, and sometimes produce more than 100 small blossoms at a time.
One of the most popular oncidiums, ‘Sharry Baby Sweet Fragrance’, is an excellent orchid for beginners. Comprised of one or two pairs of pseudobulbs, this modest plant sends up a branched flowering spike 18–30 in/45–75 cm long, clad with red-and-white, chocolate-scented flowers. Grow it in a heavy clay pot, and install a sturdy stake when blooming appears imminent. This orchid blooms when she’s ready, which may be summer, fall, or spring. She sometimes blooms twice a year.
Dancing ladies orchid (Oncidium hybrid)
Light: Year round, bright. If moved outdoors in summer, protect the plant from direct sun.
Temperature: From late fall through late winter, cool (60°F/16°C nights and days in the 75°F/24°C range). In spring and summer, intermediate (65°F/18°C nights and 75–80°F/24–27°C days).
Fertilizer: In spring and summer, feed every third time you water, mixing the fertilizer at half the normal strength. In fall and winter, feed monthly. This orchid is sensitive to fertilizer burn, so never use full-strength plant food.
Water: In summer, water as often as needed to keep media lightly moist. From fall to spring, let the plant become almost dry between thorough waterings.
Soil: Orchid potting mix.
Repotting: Every 2 to 3 years, to refresh the potting mix.
Longevity: Indefinitely, due to ease of propagation.
Propagation: When plants have developed more than six pseudobulbs, divide them into clusters of three or more when repotting. Plants should not need to be divided more often than every 7 to 8 years.
Selections: Beyond ‘Sharry Baby’ variations, any onicidium with “cat” in its name is a good bet. ‘Bobcat’ bears numerous dark burgundy blossoms on branching spikes. The blossoms of ‘Wildcat’ orchids are an exotic blend of red, mahogany, yellow, and white.
Display tips: Keep in a sunny east or west window when not in bloom. As the flower spike develops, put your onicidium to work as a tall, columnar floor plant.
FAMILY: ORCHIDACEAE ORIGIN: ASIA
MOST OF THE 60 SPECIES OF “PAPHS” are forest ground-dwellers, so they need less light than other orchids. All produce blossoms comprised of top and side petals that frame a pouch, or slipper (pedilium is Latin for shoe). Blooms last for 8 weeks or longer, and colors range from dainty pinks to exotic combinations of brownish slippers flanked by wildly mottled wing petals. Bloom time varies with selection and growing conditions, and some bloom intermittently all year. These orchids are slow growers, equipped with fleshy leaves that range from 6–12 in/15–30 cm long. As a general rule, paphs with green leaves prefer cool growing conditions, while those with mottled leaves need more warmth. All need high humidity in the 60 to 70 percent range.
Lady’s slippers (Paphiopedilum hybrid)
Light: Moderate, from an east or west window or bright fluorescent light. Keep plant in shade if you move it outdoors in summer.
Temperature: Cool to moderate (60–80°F/16–27°C), with a 15°F/8°C difference between night and day, year-round.
Fertilizer: Add a balanced houseplant fertilizer mixed at half the normal strength to the water every third watering in summer. Feed every 3 weeks in winter, diluting fertilizer to one-fourth the normal strength.
Water: Keep potting medium lightly moist at all times. Drench pots occasionally to leach out excess salts.
Soil: Orchid potting mix, with a pinch or two of lime added to reduce acidity.
Repotting: Gently repot annually, because orchid potting medium breaks down fast when it is kept constantly moist.
Longevity: Many years.
Propagation: Mature plants develop small offsets at the base, which can be cut away and repotted. Or you can allow plants to form large clumps and divide them. Division is seldom necessary more often than every 4 to 5 years.
Selections: Hybrids grow a little faster than many species selections, and tend to be heavy flowering, too. ‘Darling Christiane’ bears single pink-and-cream blossoms with comely freckles. ‘Laser’ blossoms are deep wine red.
Display tips: This is an excellent orchid to grow in a simple clay pot, which can be displayed in a prominent place when it is in bloom.
FAMILY: ORCHIDACEAE ORIGIN: TROPICAL ASIA
MOTH ORCHIDS ARE NO MORE DIFFICULT to grow successfully in homes and offices than many other houseplants, since they prefer moderate light, comfortable room temperatures, and most grow to 15–24 in/37.5–60 cm when in full bloom. The broad green leaves spread outward, so the plants are wider than they are tall when not in flower.
Several blossoms appear on each flowering spike, and sometimes a second flower spike emerges when the first one is cut. Flowers last 6 weeks or longer. The flat blossoms with sensual centers may be white, pink, or yellow, or show intricate mottled patterns. Moth orchids develop sturdy roots, including some that wander over the surface of the pot, perhaps in search of a convenient tree limb.
Moth orchids (Phalaenopsis hybrid)
FAMILY: LABIATAE ORIGIN: AUSTRALIA
POPULAR AND EASY TO GROW, Swedish ivy is a wonderful houseplant for beginners. Average to cool room temperatures and acceptance of average humidity make Swedish ivy a good choice for both home and workplace. In addition to producing cascading stems studded with glossy, rounded leaves with scalloped edges, Swedish ivy often blooms in late spring or early summer. As with other members of the mint family, the white or pale mauve blooms appear on short spikes.
After the flowers fade, pinch back stem tips to encourage the plant to develop new branches. You can prune back individual branches anytime, and even severe pruning will not kill this exuberant plant. Stem tip cuttings taken in summer, after the plants have bloomed, are easy to root and grow into new plants. Swedish ivy can be grown indoors year-round, or you can move it outdoors in the summer. If indoor space for plants is limited in winter, prune back the plants by half their size and allow them to rest in a cool place until spring. As long as they are watered occasionally and protected from freezing temperatures, they will recover quickly when brought into a warm room and given good care in spring.
Swedish ivy (Plectranthus australis)
Leaves are dull and droopy.
CAUSE: Too much light.
REMEDY: Move to a shadier location, and increase fertilizer to help the plant recover from the stress of excessive light.
Plant does not bloom.
CAUSE: Excessive nitrogen fertilizer; insufficient light.
REMEDY: Switch to a high-phosphorous (low-nitrogen) plant food in spring. Position plant so that it is exposed to more natural light as days become longer and brighter.
White cottony masses on stems and leaf undersides.
CAUSE: Mealybug.
REMEDY: Swedish ivy is often among the first plants to be infested with this pest. Isolate plant, remove mealybugs by hand with a cotton swab, and treat with insecticidal soap. See page 272 for more information on managing mealybugs.
Leaves pale; webby material on leaf undersides.
CAUSE: Spider mites.
REMEDY: Identify this pest using the information on page 276. Once a positive diagnosis is made, prune plant back severely so that only 3–4 in/7.5–10 cm of stem remain. Clean remaining foliage carefully, and isolate plant. Spray with insecticidal soap if needed to kill surviving mites.
Entire plant wilts and does not recover when watered.
CAUSE: Root rot.
REMEDY: Take stem tip cuttings from healthiest branches and root them in damp seed-starting mix. Dispose of parent plant.
FAMILY: PRIMULACEAE ORIGIN: EUROPE AND ASIA
PRIMROSES INCLUDE OVER 425 SPECIES of wildflowers and garden beauties, four of which are grown as fragrant flowering house-plants. The most popular primroses are inexpensive P. acaulis hybrids, which hold bright flowers very close to the crown on short stems; flowers often have contrasting yellow eyes. The flowers of hybrid English primrose (P. polyantha), fairy primrose (P. malacoides), and German primrose (P. obconica) are held higher, on upright stems, and they tend to bloom a little longer than the little guys. Still, regard indoor-grown primroses as temporary investments, rather like cut flowers with leaves and roots.
All species mentioned above are cool-natured plants that are grown from seed started in summer in cool greenhouses. They are ready for sale 4 to 5 months later, from December onward. Choose plants with buds that have just begun to open, and inspect them closely for any signs of insect activity. The most challenging aspect of keeping primroses happy is watering them frequently. Pinching off individual blooms helps extend the plants’ bloom time. Many gardeners set plants outside in the garden in moist partial shade after the last spring frost passes. With luck, the plants will persist for several seasons.
Primrose (Primula polyanthus)
Light: Bright indoor light but no direct sun.
Temperature: Cool (50–70°F/10–21°C).
Fertilizer: Little needed when plants are grown in pots.
Water: Constant moisture is critical, as plants wilt very quickly.
Soil: Any good potting soil.
Repotting: Generally not needed.
Longevity: A few weeks to 6 months when grown indoors. In frost-free climates, some selections can be grown outdoors as winter annuals. In cooler climates, primroses often grow as short-lived perennials.
Propagation: Seeds started indoors in fall or late winter.
Selections: ‘Libre’ German primrose (P. obconica) does not irritate skin, which was a problem with earlier varieties of this species. Choose other primroses based on the color and form you want.
Display tips: Group several plants together in a basket, with the space between the pots filled with moss or another natural material. Slip small plants into more decorative ceramic pots for temporary display on a tabletop in a well-lit room.
Flowers open pink and turn darker over a period of days.
CAUSE: Flowers naturally darken as they age, especially on P. obconica.
REMEDY: Use hue as a cue to flower age, and pinch off the oldest ones to promote the formation of new bud-bearing stems.
Flowers last only a couple of days.
CAUSE: Warm temperatures.
REMEDY: Keep plants in your coolest room at night or when you are not at home. Bring them to a warm, bright room when you are present to appreciate them.
Leaf edges appear crinkled and begin to turn brown.
CAUSE: Salt buildup in containers.
REMEDY: Flush containers with several changes of fresh filtered water, watering until water drips freely from the bottom of the pots each time. Trim off browned leaves to keep the plants looking neat.
Leaves and flowers wilt.
CAUSE: Too dry, or direct sunlight.
REMEDY: Check to make sure soil in the pot is very moist. Keep a small pitcher near plants to make watering convenient. Place plants where they will not cook in direct sun.
Leaves are yellowish, with faint webbing on leaf undersides.
CAUSE: Spider mites.
REMEDY: Dispose of the plant. Otherwise, this pest can quickly spread to more long-lived house-plants.
Leaves wilt despite correct water and light.
CAUSE: Aphids or root rot.
REMEDY: Check leaf undersides for aphids, which also can hide in the plant’s crown. Rinse plants thoroughly and spray with insecticidal soap. Dispose of plants affected by root rot, as it cannot be cured.
FAMILY: ERICACEAE ORIGIN: MAN-MADE HYBRID OF JAPANESE SPECIES
INDOOR AZALEAS ARE SO BEAUTIFUL that they deserve their popularity as Mother’s Day plants. When kept in a cool room, an azalea will hold its delicate blooms for 3 to 4 weeks, followed by a light flush of new leaves. Enjoy your azalea as a living bouquet, because florist’s azaleas are difficult to rebloom unless you live where winters are short and mild. Unlike hardy garden azaleas, which shed their leaves in winter, the florist types are tender evergreens that cannot tolerate freezing temperatures. The plants also need bright light indoors, equivalent to dappled shade outdoors, if they are to stay strong enough to set numerous buds and blooms. That said, getting a florist azalea to rebloom is challenging but not impossible, especially if you have a place outside where the plant can be placed for several weeks in the fall. Cool fall weather, or mild winter weather, is needed to help the plant set buds that open in spring.
Azalea (Rhododendron hybrid)
Light: Indoors, bright. Outdoors, mostly shade.
Temperature: Cool to average room temperatures (60–75°F/16–24°C) while in bloom. Outdoors, above 40°F/4°C. Needs 6 weeks of 40–50°F/4–10°C fall weather to set buds.
Fertilizer: Twice yearly, feed plants with an acid-forming azalea fertilizer that contains iron, a necessary micronutrient.
Water: Keep soil lightly moist at all times, and prevent dryness in the center of the root mass by plunging pot into a larger container of water weekly. Keep it submerged until no bubbles appear, then allow pot to drain until dripping stops.
Soil: If you plan to keep the plant, repot it into a half-and-half mixture of peat moss and potting soil.
Repotting: Not necessary for a plant kept as a temporary bouquet. If you want to rebloom your plant, shift it to a larger pot after the last blooms have withered.
Longevity: A few months to several years.
Propagation: Rooted stem tip cuttings, though rooting is slow and the results seldom match the quality of plants produced by commercial growers.
Selections: Choose plants based on the flower color you like, which may be pink, red, white, or salmon. White flowers show imperfections more than other colors.
Display tips: Enjoy a potted azalea in very close quarters during the weeks it is in bloom.
Leaves turn brown while still attached to stems.
CAUSE: Root rot.
REMEDY: Several types of soil-borne fungi can cause azalea roots to rot. Infected plants will slowly (or quickly) die, and should be discarded.
Plant sheds many leaves.
CAUSE: Side effect of dry soil conditions, past or present.
REMEDY: Make sure plant is thoroughly watered, either by soaking container in a sink or bucket or by repeatedly watering it. The plant may have been allowed to dry out before it came to live with you, and is showing its displeasure. Discard a plant that has lost more than one-third of its leaves, as it will never recover.
Leaves turn yellow, while leaf veins remain green.
CAUSE: Iron deficiency.
REMEDY: Spray plant with a chelated iron product. You may also increase fertilizer after checking to make sure iron is present in the fertilizer you are using on your azalea.
Plant does not rebloom, or reblooms very lightly.
CAUSE: Lack of cold weather to help set buds.
REMEDY: In fall and winter, a florist azalea needs at least 6 weeks of temperatures between 40–55°F/4–13°C in order to set buds. Keeping the plant outdoors in the fall and then moving it to an unheated garage where it will be chilled, but not frozen, is usually best.
Leaves appear parched, with webby material on leaf undersides.
CAUSE: Spider mites.
REMEDY: Isolate plant and prune off badly infested stems. If more than one-third of plant is infested, disposing of it is usually better than attempting to get rid of the mites. See page 274 for more information about this pest.
FAMILY: ROSACEAE ORIGIN: CHINA
MINIATURE ROSES THAT GROW less than 18 in/45 cm tall have recently won places on store shelves, especially in spring from Valentine’s Day to Mother’s Day. Varieties that grow to less than 14 in/35 cm tall are often called micro-roses. Although mini- and micro- roses are sold alongside other indoor plants, their true home is outdoors. Roses need 6 hours of direct sun daily in order to thrive, so they must be moved outside at the earliest possible time if they are to live long, happy lives. In spring, enjoy a new plant indoors until the last frost passes, and then repot it and place it outdoors on your porch or patio. Miniature roses will grow in pots, but they also make great garden plants. Tremendously hardy, miniature roses that are transplanted to the garden in late spring easily survive winter in cold climates when protected with a mound of mulch or loose soil. Allow container-grown plants to become dormant in winter, and keep them in a garage or other protected place in winter so their roots will not freeze.
Miniature rose (Rosa chinensis hybrid)
Light: Bright light, including as much direct sun as possible.
Temperature: Average room temperatures (60–75°F/16–24°C). Outdoors, plants adapt to temperature extremes, provided they are well rooted.
Fertilizer: Fertilize monthly with a balanced fertilizer that contains micronutrients.
Water: Allow soil to dry to within .5 in/1.25 cm of surface between thorough waterings.
Soil: Any good potting soil.
Repotting: When initial flush of flowers fades, remove plant from pot and soak roots in water to separate plants (frequently there are more than one). Tease apart roots and transplant to individual 6 in/15 cm pots.
Longevity: A few months indoors, to many years when grown outdoors in open sun.
Propagation: Root stem tip cuttings taken in early summer as described on page 299. Use rooting powder and maintain high humidity.
Selections: There are more than 100 named varieties, which vary in size, color, fragrance, and bloom type. Pink ‘Cupcake’ is a top choice. Other award-winning miniature rose varieties are listed at the website of the American Rose Society (www.ars.org).
Display tips: Enjoy a gift plant indoors while the blooms last, which is usually 4 to 6 weeks. Then move plant outdoors.
Buds shrivel before they open.
CAUSE: Very dry air.
REMEDY: After being grown in humid greenhouses, plants often go into shock when moved to dry indoor rooms. Clip off failed buds and mist plant daily for 2 weeks. Plant may not fully recover until it is repotted and moved outdoors.
Plant appears healthy but does not bloom.
CAUSE: Not enough light.
REMEDY: Miniature roses need very bright light before they will produce buds and flowers. If you do not have a place where they can receive 6 hours of sun daily, grow them within 2 in/5 cm of fluorescent lights.
Leaves develop black spots, with yellow between the spots.
CAUSE: Rose blackspot, a common fungal disease.
REMEDY: Clip off affected leaves as soon as you see them. Try to keep leaves dry when watering, as blackspot spreads on damp leaf surfaces. Plants that lose most of their leaves to this disease often recover when given good care. Resistance varies greatly with variety.
Leaves appear bleached, with faint webbing on leaf undersides.
CAUSE: Spider mites.
REMEDY: Roses are very susceptible to this pest, described on page 274. Isolate plant, prune off badly infested branches, and thoroughly clean plant with plenty of warm water. Spray plant with insecticidal soap, and move it to a shady spot for a few days. Increasing humidity often helps prevent spider mite problems.
Leaves turn yellow and fall off.
CAUSE: Environmental stress.
REMEDY: When roses are kept in the dark too long while they are shipped to stores, allowed to dry out, or exposed to high temperatures, they often shed their leaves and enter a state of semi-dormancy. Allow plant to rest in a cool place for 2 weeks, then repot and resume normal care. Assuming the plant receives bright light, it may recover. Roses naturally shed their leaves in winter.
FAMILY: LAMIACEAE ORIGIN: WESTERN EUROPE
SEVERAL POPULAR CULINARY HERBS can be grown outdoors in summer and kept indoors in winter, but rosemary is the best one to grow indoors year-round. Strong light is needed to grow compact plants, but even a plant that stretches toward the light will bear plenty of flavorful leaves for cooking. Varieties vary in their size and growth habit. Very compact strains grow into bushy plants less than 18 in/45 cm tall, while those with a trailing habit make fine subjects to train onto a hoop or other topiary form. Varieties also vary in their willingness to bloom. All bloom best when given a cool rest period in winter. The strongest bloom season is late spring. After plant blooms, trim back old stems to encourage the emergence of plenty of stocky new side branches.
If you begin with a plant that has been pruned into the shape of a Christmas tree, expect it to become bushier over time. These are usually 2-year-old plants, which will begin to deteriorate after another year. Stem tip cuttings propagated from tree-form plants will not have the same shape as their parent unless they are grown in full sun and trained by meticulous pruning.
Rosemary (Rosmarinus officinalis)
Light: Spring through summer, bright light, including 4 hours or more of direct sun. In fall and winter, can adapt to less light. In any season, turn plant weekly to give all sides a turn at directional light.
Temperature: From late spring to late summer, warm (60–80°F/16–27°C). In fall and winter, cool (45–70°F/7–21°C).
Fertilizer: From spring through summer, feed every 2 weeks with a balanced all-purpose plant food. In fall and winter, feed monthly.
Water: Allow soil to dry to within 1 in/2.5 cm of the surface between waterings. Be careful not to overwater, as this plant needs somewhat dry conditions. However, it should not be allowed to dry out completely.
Soil: Any good potting soil, with a small amount of sand added to provide a gritty texture. Cactus potting soil, which contains a lot of perlite, is also a good choice.
Repotting: Annually in spring. Clay pots, which help the roots dry out between waterings, are ideal for rosemary.
Longevity: About 4 years for individual plants, which can be kept indefinitely when propagated from stem tip cuttings.
Propagation: In summer, take 3 in/7.5 cm stem tip cuttings and root them as described on page 299. Roots develop in about a month.
Selections: ‘Blue Boy’ and a few other varieties are very small and compact, making them ideal for growing in pots. Trailing varieties such as ‘Lockwood’ and ‘Santa Barbara’ can easily be trained to grow as topiary.
Display tips: Plenty of warm sun brings out the best in rosemary’s flavor. Keep your plant near the kitchen so it will be convenient to use in cooking.
Little new growth; some yellowing of old leaves.
CAUSE: Too little fertilizer; acidic growing conditions.
REMEDY: Repot plant in fresh potting soil. Mix ½ teaspoon/2.5 ml of lime into the soil. Increase frequency of feeding, but do not fertilize rosemary with a very strong fertilizer solution.
Stems floppy, with spaces between leaves.
CAUSE: Not enough light.
REMEDY: When grown outdoors, rosemary enjoys baking in full sun. Indoors, give plants as much direct sun as possible in summer, when most new growth is produced. If you cannot place plant in a south or west window, shift it outdoors for the summer.
Plant does not bloom.
CAUSE: Not a heavy-blooming variety, or lack of cool winter temperatures.
REMEDY: Rosemary blooms best when it feels seasonal changes — cooler in winter and warmer in summer. Some varieties bloom much more enthusiastically than others. To encourage flowering, give plant a cool winter rest and switch to a high-phosphorous plant food for a few weeks in spring.
FAMILY: GESNERIACEAE ORIGIN: EASTERN AFRICA
THE CHEERY BLOSSOMS AND DOWNY LEAVES of African violets have won them the number one spot among flowering houseplants, and they are quite easy to grow. Always dainty in demeanor, African violets are excellent plants to grow on a windowsill that receives light filtered through the leaves of outdoor trees. They are at their best when kept indoors year round. African violets can be damaged by overwatering, chilling, or placement in harsh sun, but otherwise these stalwart little plants seldom complain. Don’t be reluctant to buy plants that are in bloom, because African violets bloom again and again when given reasonable care. Do pinch off old flower stems to keep the plants looking neat.
African violet (Saintpaulia hybrid)
Light: Bright indirect light or fluorescent light.
Temperature: Average room temperatures (65–75°F/18–24°C) year-round.
Fertilizer: Feed every 2 weeks with a high-phosphorous plant food, or use a balanced houseplant food mixed at half the rate recommended on the package.
Water: Keep soil lightly moist at all times. Water thoroughly with lukewarm water, and then pour off any excess water that accumulates in the pot tray. In summer, leach pots once or twice to remove accumulated salts (see page 263). Avoid wetting the leaves when watering.
Soil: A peaty potting soil or African violet mix.
Repotting: Repot once a year to refresh soil but keep plants in small pots. When repotting, prune off up to one-third of the roots and set the plant slightly deeper in the pot.
Longevity: With attentive care, plants have been known to live 50 years.
Propagation: Root healthy, medium-sized leaves with 1–2 in/2.5–5 cm of stem attached as described on page 299. Leaves develop roots in about a month, and plantlets form within 4 to 6 weeks after that.
Selections: Choose plants based on flower colors you like. Collectors grow African violets that have unusual flower forms, including doubles, bells, and star-shaped blossoms, and there are variations in leaf type, too.
Display tips: A single plant in a pretty ceramic pot makes a lovely desktop accent. Group small plants together in a shallow basket, using Spanish moss or sphagnum moss to fill the crevices between the containers.
Plant does not bloom.
PROBLEM: Too little light; lack of darkness.
REMEDY: African violets sometimes stop blooming in winter, when light levels are low. Move plants to a bright south or west window in winter to keep them in bloom. In spring and summer, keep them where light is less intense and switch to a high-phosphorous fertilizer. Some people add a light pinch of Epsom salts to water to push balky plants into bloom. Plants also may fail to bloom if they do not receive 8 hours of darkness each night.
Old leaves shrivel to brown.
PROBLEM: Normal for African violets.
REMEDY: Pinch off old leaves as they fail and dispose of them. Plants that are underfed shed leaves more quickly than those that are adequately fertilized.
Plant grows lopsided, curving to one side.
PROBLEM: Natural response to directional light.
REMEDY: In the wild, African violets grow between rocks, curving as needed to get the best light. To correct this shape requires renovating the plant. Remove all leaves except seven or eight in the central crown, then remove the old roots, leaving a 3 in/7.5 cm trunk. Use a knife to peel the lowest 2 in/5 cm of the trunk, like a carrot. Set the groomed plant to root as if you were rooting a stem cutting (see page 299). When new growth appears, transplant into African violet soil.
Brown spots on leaves.
PROBLEM: Cold water on leaves; any water on leaves when plant is in bright light.
REMEDY: Avoid wetting leaves when watering. If leaves need to be cleaned, either brush them lightly with a dry paintbrush or rinse them with lukewarm water on a warm, dry day. Place plant in a shady spot until the leaves are dry.
Leaves bleached and wilted; tiny insects on leaf undersides.
PROBLEM: Cyclamen mites.
REMEDY: This pest is very difficult to control. Dispose of infested plants, and isolate any others that were growing nearby.
FAMILY: SAXIFRAGACEAE ORIGIN: EASTERN ASIA
IF YOUR SPACE FOR HOUSEPLANTS IS LIMITED and you want only plants that grow and change quickly, strawberry begonia is an excellent choice. Often grown outdoors as a groundcover in Zones 6 to 9, this tough little saxifrage makes a pleasing, carefree houseplant. Growing to 6 in/15 cm tall and 12 in/30 cm wide, strawberry begonia produces rounded leaves in rosettes with hairy red leaf undersides and stems. In spring, plants may produce sprays of tiny white flowers, especially if the plant is allowed to rest for a few weeks in winter in a cool place (50–55°F/10–13°C). Strawberry begonia’s leaves and petite form are attractive, and robust crops of little plantlets borne on dangling runners to 24 in/60 cm long add to its charm. These are easily grown into new plants to keep or share. Should the plantlets become so numerous that the plant appears unkempt, thin them by clipping off unwanted runners close to the plant’s crown.
Strawberry begonia (Saxifraga stolonifera)
Light: Bright, from an east or west window.
Temperature: Cool to average room temperatures (50–75°F/10–24°C).
Fertilizer: In spring and summer, feed monthly with a balanced plant food. In fall and winter, feed every 6 weeks.
Water: Allow soil to dry to within 1 in/2.5 cm of the surface between waterings. Water more in summer than in winter, when plant often rests.
Soil: A fast-draining potting soil that contains perlite or sand, with pebbles added to the bottom of the container for enhanced drainage and extra weight.
Repotting: Repot each spring until the plant’s third year, when the crowns often become woody and prone to rot. Replace old plants with rooted plantlets.
Longevity: 3 years for individual plants, or indefinitely when plantlets are propagated.
Propagation: Use a bent paper clip to pin plantlets into small pots set around the parent plant, where they will quickly grow roots. Detach from parent plant after three weeks. Transplant three rooted plantlets into a shallow, 6-inch pot.
Selections: The ‘Tricolor’ variety features green leaves with splashy cream margins, delicately edged with red. It requires more exacting care than species selections, which have green leaves with silver markings along the veins.
Display tips: Young plants can be grown in small pots for a year. In the second year, shift them to hanging pots or baskets, so the plantlets can arch downward.
Leaves are pale and brownish.
CAUSE: Too little light; too much sun.
REMEDY: This plant needs some direct light, but strong sun can bleach the leaves. Try it in an east window, which is usually an ideal setting.
Plant droops or collapses.
CAUSE: Chronic overwatering; acute dryness.
REMEDY: Waterlogged roots can cause plant to droop, but it should perk up when the soil is allowed to dry out. Should plant become so dry that it collapses, rehydrate container as described on page 328.
Old leaves yellow and turn brown.
CAUSE: Plant is too old; roots may be rotting.
REMEDY: Propagate new plant by rooting a few plantlets. When they show strong growth, discard the parent plant.
Leaves shrivel; mold appears at soil line.
CAUSE: Root or crown rot, caused by botrytis or another soil-borne fungus.
REMEDY: If only one crown in the container is affected, use a sharp knife to cut it out. Meanwhile, propagate new plant by rooting plantlets, as other crowns in the container may become infected. Moist soil conditions favor this problem.
Small wedge-shaped insects are seen on new leaves.
CAUSE: Aphids.
REMEDY: Thoroughly clean plant with plenty of warm water. If problem persists, spray plant with insecticidal soap.
Leaves pale and bleached, with faint webbing on leaf undersides.
CAUSE: Spider mites.
REMEDY: Isolate plant, and snip off badly affected leaves. Thoroughly clean plant with plenty of warm water. Swish plantlets in a bowl of soapy water, then rinse and pin them in pots to grow new roots. Older plants that have suffered a serious infestation may never recover, but young plants free of mites often prosper when given good growing conditions.
FAMILY: ASTERACEAE ORIGIN: CANARY ISLANDS
INSTEAD OF THINKING OF CINERARIA as a houseplant, regard it as a living cut flower. These lovely bloomers are grown as annuals that begin their lives as seeds sown in greenhouses in summer. Four months later, after a strict regimen of controlled temperatures that start out warm and are made progressively cooler, the seedlings are poised to explode with dense trusses of starry, daisy-shaped flowers. Cinerarias are usually sold from January through April, so they are perfect plants for providing late-winter color indoors.
Cinerarias hold their blossoms best if they are kept in a cool room where temperatures never rise above 65°F/18°C. If you have a cool porch, move your plants there at night, because cinerarias find cool (50°F/10°C) nights quite pleasing. Don’t worry if temperatures dip to 40–50°F/4–10°C, because cool nights do the plants no harm. Cinerarias will wilt quickly should they become dry, so watch them closely for signs of drought stress. Seriously wilted plants may never recover from the trauma. Use scissors to snip off individual blossoms as they fade. When the blooming period ends, discard the plants.
Cineraria (Senecio × hybridus)
Light: Bright diffuse sunlight.
Temperature: Cool (50–65°F/10–18°C).
Fertilizer: None needed.
Water: Keep constantly moist at all times, but avoid overwatering. Plants benefit from high humidity.
Soil: Any potting soil.
Repotting: Not needed, unless you want to shift a purchased plant to a more decorative container.
Longevity: 1 bloom season that usually lasts 4 to 6 weeks.
Propagation: Seeds sown in late summer.
Selections: Choose plants by color of the blooms. Most of the cinerarias offered for sale are of the ‘Jester’ variety, which comes in five colors and grows to 10 in/25 cm tall.
Display tips: Place pots inside wicker baskets to display on tabletops when the plants are in full bloom. Three pots, placed together in an oblong planter, make a great indoor windowbox for a cool north window.
Leaves appear pale and limp.
CAUSE: Too much direct sun.
REMEDY: Move plants to filtered light. Light from south or west windows is often too bright, with warmer temperatures than these plants like.
Plants wilt daily.
CAUSE: Uneven watering. The interior of the root mass may have become extremely dry, so that it sheds water rather than absorbing it.
REMEDY: Water plants thoroughly, then set the containers in a pan of water for half an hour to rehydrate them. Remove and allow excess water to drain away.
Flower colors are pale.
CAUSE: Too little light.
REMEDY: Move plants to a brighter spot, where they will receive filtered sun for a few hours each day.
Blossoms fade within a few days after buds open.
CAUSE: Warm temperatures.
REMEDY: Move plant to a cooler place. Cineraria blossoms last much longer when plants are kept in a place where temperatures stay below 65°F/18°C.
Plants collapse and will not perk up after watering.
CAUSE: Root rot.
REMEDY: Discard plants.
Small insects are present on plants.
CAUSE: Aphids, whitefly, or thrips.
REMEDY: Discard plants, because these pests can spread to other, more long-lived houseplants.
FAMILY: GESNERIACEAE ORIGIN: BRAZILIAN RAIN FORESTS
NOT SO LONG AGO, these African violet cousins were grown as perennial plants that died back and became dormant for 3 months each year. The tuberous root was then replanted in fresh soil, and it promptly regrew, delighted its owners with big, velvety flowers, and gradually faded back to dormancy again. This story has changed, in that most gloxinias sold in florist shops and retail stores these days are hybrids grown as annuals. Bred to grow quickly from seed, today’s gloxinias are so focused on flowering that they don’t invest energy in a serviceable storage root. Their ability to rebloom is therefore seriously compromised, and plants that do come back after a period of dormancy are not likely to show good vigor.
An annual houseplant can still be a great houseplant, however, so don’t be afraid to invest a few dollars in a pretty gloxinia. Choose plants with buds that are just beginning to open. Each blossom will last about a week, and the bloom period should last about 2 months. Should serious insect problems arise — for example, an outbreak of spider mites, cyclamen mites, or thrips — it is best to discard the plant rather than working with pesticides or soap sprays, which usually ruin gloxinia blossoms.
Gloxinia (Sinningia speciosa hybrid)
Light: Bright filtered sunlight.
Temperature: Average room temperatures (60–75°F/16–24°C).
Fertilizer: Feed every 2 weeks with high-phosphorous plant food.
Water: Keep soil moderately moist. Dryness induces dormancy. When watering, avoid wetting the leaves.
Soil: Light-textured potting soil with extra peat, or African violet soil.
Repotting: Not needed for short-lived plants. When handled as perennials, repot in late winter, as plants emerge from dormancy.
Longevity: 2 months to several years.
Propagation: Seeds sown indoors in late winter.
Selections: Gloxinias come in three sizes. Regular gloxinias feature huge flowers to 3 in/7.5 cm across, and the plants are usually sold in 6 in/15 cm pots. Smaller, compact gloxinias, sold in 4 in/10 cm pots, have smaller flowers, but they are often in big clusters. Mini gloxinias are sold in 4 in/10 cm pots, or they may be the color plants in preplanted tabletop gardens. Of these three, regular gloxinias have the best chance of coming back after a 2 to 3-month dormancy period.
Display tips: Place blooming gloxinias on a tabletop or bookshelf where the velvety blossoms are easy to see. Use small pieces of statuary or decorative containers to showcase gloxinias in full bloom.
Brown spots on leaves.
CAUSE: Water spots.
REMEDY: Water plants in the morning so that any water that gets on the leaves dries quickly. Avoid wetting the leaves when watering the plants.
Bleached rings on leaves.
CAUSE: Cold water.
REMEDY: Use warm water (above 55°F/13°C) when watering gloxinias.
Twisted, cupped, or curled new leaves.
CAUSE: Too much nitrogen fertilizer.
REMEDY: Reduce feeding, and be sure to use a high-phosphorous plant food rather than a balanced one, which may contain too much nitrogen.
New leaves appear eaten around the edges.
CAUSE: Boron deficiency.
REMEDY: Drench plants with a boron solution made from Epsom salts, as described on page 18.
Leaves are yellow, or mottled with yellow.
CAUSE: Too much direct sunlight. If only oldest leaves are yellow, the plants may be entering their dormant period.
REMEDY: Move to filtered light, or allow plant to dry out and become dormant.
Leaves appear pale and bleached.
CAUSE: Spider mites or cyclamen mites (page 274).
REMEDY: Discard plants.
Flowers are deformed, appear chewed.
CAUSE: Thrips (page 276).
REMEDY: Discard plants.
FAMILY: SOLANACEAE ORIGIN: SOUTH AMERICA
A TOUGH LITTLE SUBSHRUB, Jerusalem cherry is related to tomatoes and edible peppers. However, the fruit is toxic, so advise children not to pick them, and keep them out of the reach of pets. These safety precautions aside, Jerusalem cherry makes a versatile indoor plant in fall and winter. After a quiet show of starry white flowers, round, cherry-sized fruits start out dark green, then become Halloween yellow, and slowly ripen to red as Thanksgiving gives way to Christmas. In spring, the plant can be pruned back and placed in a cool place to rest. After the last spring frost passes, move it outdoors and it should regrow without delay.
Plants more than 2 years old often become brittle, so it’s a good idea to propagate stem cuttings from year-old plants. Easier still, gather the ripe fruits and plant them in a pot or on any piece of moist ground in spring. Seedlings will almost certainly appear, and these can be dug, potted up, and adopted as replacements for aged specimens.
Jerusalem cherry (Solanum pseudocapsicum)
Light: Bright, including direct sun for up to 4 hours a day.
Temperature: Average to warm room temperatures (65–75°F/18–24°C).
Fertilizer: From spring to early winter, feed monthly with a balanced houseplant food or a water-soluble tomato fertilizer. In late winter, no feeding necessary.
Water: Allow soil to become dry to within 1 in/2.5 cm of the surface between waterings, but do not let soil become so dry that the plant wilts.
Soil: Any good potting soil.
Repotting: Repot young plants as they become rootbound until the roots fill a 6 in/15 cm pot. In spring, repot year-old plants to refresh soil.
Longevity: 2 to 3 years, or indefinitely when propagated from seeds or rooted stem cuttings.
Propagation: Take stem cuttings in spring and root them as described on page 299. Plants are also easily grown from seed gathered from shriveled fruits. Seedlings started outdoors in early summer bloom and set fruit the following fall.
Selections: In addition to this species, less shrubby ornamental peppers (Capsicum frutescens) are sometimes sold as holiday plants. These are not as long lived as Jerusalem cherry, and should be discarded after their fruits are no longer attractive.
Display tips: Use sharp scissors to shape plant before displaying it in a sunny window. A cloth wrapping placed over the pot can change with the fall and winter holidays, keying the plant to the most appropriate theme. This plant makes a great sidekick for a larger calamondin orange.
Plant blooms but does not set fruit.
CAUSE: Poor pollination.
REMEDY: When grown outdoors, wind helps move pollen to where it is needed, but indoors there may not be enough air movement. Jiggle the plants a few times a day when they hold many open flowers, or use a small dry paintbrush to dab the centers of the blossoms, which spreads the tiny grains of pollen.
Leaves are small and light green.
CAUSE: Insufficient fertilizer.
REMEDY: Plants grown in pots need regular feeding. Increase frequency of fertilizer application.
Plant does not bloom.
CAUSE: Insufficient light; too much supplemental light at night.
REMEDY: These plants look best in winter when they enjoy strong outdoor light during the summer. They also fruit best in response to days becoming shorter in the fall. To support this process, leave your plant outside as long as possible, but do bring it in before temperatures drop to freezing.
Leaves sticky; small insects are present.
CAUSE: Aphids, whiteflies, or spider mites.
REMEDY: Gather fruits for replanting and dispose of plant. This plant is short lived by nature, and it is easier to grow replacements than to restore the health of an infested plant.
FAMILY: ARACEAE ORIGIN: INDONESIA AND CENTRAL AMERICA
SPATHIPHYLLUMS ARE PRESENT in most offices, malls, and homes for good reason. They are easy to grow, produce showy, spoon-shaped flowers, and tolerate low light and average humidity. In NASA studies, spathiphyllums were found to help remove formaldehyde, benzene, and carbon monoxide from tainted indoor air. Small varieties grow to only 16 in/40 cm tall, with the largest ones often reaching 6 ft/1.8 m in height and width.
When purchased or received as gifts, spathiphyllums usually hold several flowers. Cut off these flowering stems when the blossoms ripen to green. Use a soft, damp cloth to wipe dust from the foliage, and do not expect a fresh crop of blooms until the following summer. Once plants have been nicely situated in a home or office for several months, they usually resume their natural bloom cycle. In addition to a flush of flowers in early summer, many cultivars continue to bloom intermittently throughout the year.
Peace lily (Spathiphyllum species)
Light: In fall and winter, low to moderate. In spring and summer, moderate to bright.
Temperature: Average room temperatures (65–75°F/18–24°C) year-round.
Fertilizer: From spring through fall, feed monthly with a balanced plant food that includes micro-nutrients, diluted to half the normal strength. In winter, feed every 6 weeks.
Water: Keep soil lightly moist at all times, and avoid overwatering. Use room-temperature water.
Soil: Any good potting soil.
Repotting: Repot annually in spring to refresh soil. This plant likes to be slightly rootbound.
Longevity: Many years, if divided every 5 years or so.
Propagation: Propagate older plants by dividing them in spring. Trim off leaves that fail in the weeks following division.
Selections: Dozens exist, varying in size, leaf color, and flowering habits. The giant peace lilies seen in malls and airports are usually ‘Sensation’, which grows to 6 ft/1.8 m tall. ‘Supreme’ is the most common variety sold in 10 in/25 cm pots. ‘Lynise’ has textured leaves and often grows to 36 in/90 cm tall.
Display tips: The dark leaves of peace lily appear most refined when the plant is grown in a plain pot with a glossy finish. Display blooming plants on a low pedestal where the flowers can be easily seen.
Leaf tips are brown; stems droop.
CAUSE: Overfertilization and/or overwatering.
REMEDY: Allow soil to become nearly dry before watering. Water lightly yet frequently, and avoid soaking the soil. Use a very dilute fertilizer.
Leaves are pale and curled, with brown leaf margins.
CAUSE: Excessive light.
REMEDY: Peace lily cannot tolerate direct sun. Move it to a place that gets filtered light, or near an east window. In winter, peace lilies can accept light levels that are quite low.
Plant does not bloom.
CAUSE: This plant usually blooms in cycles, with flowers produced mostly in spring and summer. Low light levels suppress blooming. Plants that are more than 5 years old may not bloom unless they are rejuvenated by dividing them.
REMEDY: In spring, move plant to a slightly brighter location and feed and water it regularly. Divide old, overgrown plants.
Yellow margins on lowest leaves, or yellow edges on all leaves.
CAUSE: Too dry; micronutrient deficiency.
REMEDY: Increase water and fertilizer. Use a dilute fertilizer that contains magnesium and iron, because peace lily is sensitive to deficiencies of these nutrients.
Small, dark-colored insects on flowers.
CAUSE: Thrips.
REMEDY: Large-flowered peace lilies in particular are attractive to thrips. Isolate plant from other blooming houseplants and implement control measures described on page 276.
FAMILY: GESNERIACEAE ORIGIN: SOUTHERN AFRICA AND MADAGASCAR
A CLOSE RELATIVE TO AFRICAN VIOLETS, streptocarpus is a larger plant, with long, strap-shaped leaves that arch outward, making it wider than it is tall. Full-sized plants grow to 12 in/30 cm tall and up to 30 in/75 cm wide. Dwarf varieties are smaller. Most streptocarpus are complex hybrids that have been bred to produce big, showy trusses of flowers that may be pink, purple, white, or red, depending on variety. Many have contrasting white or yellow throats.
A delightful plant to grow near a large window, streptocarpus needs somewhat cool temperatures to thrive. It is a wonderful plant for offices lit by fluorescent lights, and the increasing availability of vigorous hybrids have contributed to its growing popularity. Superior varieties are sold by many suppliers that specialize in African violets (see ‘Plants and Supplies’).
Cape primrose (Streptocarpus × hybridus)
Light: Moderate to bright light, or 15 hours of fluorescent light daily.
Temperature: Cool room temperatures (60–70°F/16–21°C).
Fertilizer: Feed every 2 weeks with a high-phosphorous plant food diluted to half the usual strength.
Water: Keep soil lightly moist at all times spring through summer. Water slightly less in winter, but do not allow soil to become so dry that plant wilts.
Soil: African violet potting soil.
Repotting: Repot annually in spring, being careful not to set the plant too deeply in the pot. Streptocarpus has many surface roots that should be barely covered with soil. Keep streptocarpus in small containers, because overpotting can lead to problems with root rot.
Longevity: To 10 years or more.
Propagation: Grow plantlets from rooted petiole leaf cuttings as described on page 302. Plants that develop multiple crowns can be divided.
Selections: There are dozens of named hybrids in a range of colors and bicolors. Two that are easy to grow are ‘Bristol’s Blue Bonnet’, which produces trusses of blue flowers, and ‘Dibley’s Falling Stars’, which is pale lavender with a white throat.
Display tips: Keep plant near a sunny south window where it gets abundant indirect light. Pinch off old flower stems to keep plant looking neat.
Plant does not bloom.
CAUSE: Too little light; nights too long.
REMEDY: Streptocarpus is sensitive to day length, and will not bloom unless days are at least 15 hours long. If needed, place plants beneath a fluorescent light 15 hours each day. Plants grown in natural light bloom best in late spring and early summer.
Leaf edges turn brown.
CAUSE: Overwatering; fertilizer burn.
REMEDY: Water plants lightly yet frequently to keep the soil uniformly moist. Do not feed plants that have dried out. Instead, water them until the soil is lightly moist before adding fertilizer to the water.
Outer leaves shrivel to brown.
CAUSE: This is the natural growth habit of streptocarpus.
REMEDY: Use sharp scissors or a razor blade to trim off old leaves as soon as they begin to fail.
Plants grow poorly, appear limp despite regular watering.
CAUSE: Stem or root mealybugs; root rot.
REMEDY: Check stems for white cottony masses. If mealybugs are present, remove them with tweezers. Also check for root mealybugs by pulling plant from pot and inspecting roots. Remove any mealybugs by hand, swish roots through clean water, and repot in fresh soil in a clean container. Roots that appear black have rotted. Trim them off and repot the plant in fresh soil.
Leaves show faint yellow specks and appear parched.
CAUSE: Spider mites.
REMEDY: Isolate plant and trim off badly infested leaves. Spray leaf undersides with water to dislodge mites, and repeat after three days. If problem persists, spray with insecticidal soap or a neem-based insecticide. See page 274 for more information about this pest.
