Culture

These unusual orchids offer fascinating, often waxy flowers that have the peculiar habit of discharging their pollen masses (pollinia) onto pollinators. Almost always deciduous, the pseudobulbous plants have strict growing and resting periods.

LIGHT should be strong, especially near the end of the growth period. Early in the annual growth cycle, plants will tolerate less light - from 1,500 to 3,000 foot-candles. Plants grow best with light levels of 3,000 to 6,000 foot-candles, or 1/4 to 3/4 full sun. As pseudobulbs mature, harden them by giving slightly more light.

TEMPERATURE These orchids are native to hot tropical areas and grow during rainy summer months. During this growing period, day temperatures of 80 to 100 degrees F and night temperatures of 60 to 65 degrees F are beneficial. After growths mature, temperatures should be reduced to 55 degrees F at night, with day temperatures of 70 to 85 degrees F.

WATER is critical for producing large pseudobulbs and strong flowerings. Since these plants only grow for a short period, a great quantity of water must be stored by the plant. Water heavily as new leaves are forming. After the pseudobulb is mature, gradually reduce watering frequency. The leaves will yellow and start to fall. At this time watering should be stopped completely until new growth begins again. Water during this dormant period only if the plant shrivels severely; overwatering may cause the pseudobulbs to rot and die.

FERTILIZING is very important for producing strong pseudobulbs. Use a high-nitrogen formulation (30-10-10) while plants are in active growth, slowly tapering off as pseudobulbs form. Bloom booster formulation (10-30-20) should be used in the fall except for plants that normally bloom in the spring.

POTTING is best timed to coincide with the start of new growth (s), usually in the spring. New roots will be produced quickly at that time, and plants will not experience any setback. These plants have vigorous root systems and like to have a rich and moist potting medium during their growing months. Many growers remove the plants from the growing medium during the resting period to ensure dryness during that time. Fine-grade orchid bark is common for smaller pots; medium-grade bark is used only on large plants. Sphagnum moss is used successfully for plants in many areas, as it provides tremendous water- and fertilizer- holding capacities. Some plants may be grown on slabs of treefern or other material, which makes it easier to keep them dry during dormancy; however, it is harder to keep them moist while growing. When well grown, these orchids can be divided down to one mature bulb and then bloom on the next mature growth.

Spider mites are a common pest of these orchids when in leaf; control by keeping humidity high and/or spraying with recommended miticides.

Prepared by: Education Committee, American Orchid Society

Cattleyas are among the most commonly grown orchids, and their culture is often used as the basis for comparison with other types of orchids.

The flowers in cattleyas and their related hybrids come in many colors. Culture varies only slightly among most of these groups; this cultural information is a general guide to "standard" cattleya culture.

Like most other cultivated orchids, cattleyas are epiphytes, or air-plants. Because they are epiphytic, they have developed water-storage organs, called pseudobulbs, and have large, fleshy roots covered with a spongy, water-retentive velamen. They are accustomed to being dry at the roots between waterings, and therefore should be potted in a very porous, free-draining medium.

LIGHT is one of the most important factors in growing and blooming cattleyas, whether in a greenhouse setting or in the home. Bright light to some sun must be given to the plants, but no direct sun in the middle of the day. This means at east, shaded-south (as with a sheer curtain) or west window in the home, and 30% to 50% of full sun in a greenhouse (3,000 to 5,000 foot-candles). Leaves should be a medium green color.

TEMPERATURE Recommended temperatures are 55 to 60 degrees F at night and 70 to 85 degrees during the day. Seedlings should have night temperatures 5 to 10 degrees higher. A 10 to 20 degrees differential between day and night is recommended, especially for mature plants. Higher day temperatures can be tolerated (up to 95 degrees F), if humidity, air circulation and shading are increased.

WATER should be provided in two ways: in the pot by watering and in the air as humidity. Watering in the pot is dictated by many criteria - size and type of pot, temperature, light, etc. Mature cattleyas need to dry out thoroughly before being watered again. Seedlings need slightly more constant moisture. Compare the weight of a dry pot of the same size and type of medium; it can indicate if a plant needs water. A freshly sharpened pencil inserted in the potting medium can be an indicator of moisture. If in doubt, it's best to wait a day or two until watering. Plants in active growth need more water than plants that are resting. Water below 50 degrees F may injure plants, as will softened water.

HUMIDITY Cattleyas need 50% to 80% relative humidity. This can be provided in the home by placing the plants on trays of gravel, partially filled with water so that the plants stand above the water. Misting the plants in the morning only is helpful in dry climates. Air should always be moving around the plants to prevent fungal or bacterial disease, especially if high humidity and/or cool temperatures exist. In the greenhouse the humidity can be increased by wetting the floor. Evaporative cooling increases humidity while cooling the air.

FERTILIZER must be given to cattleyas on a regular schedule. In fir bark, a high nitrogen (30-10-10) forrmulation, or a similar proportion, is used. High-phosphorus or bloom booster (10-30-20) formulation may be used occasionally (every 4 to 6 applications) to make sturdy growths and promote healthy blooming. When in active growth, plants need fertilizer every two weeks, and when not growing, once a month. Fertilizer can LEFT also be applied with every watering at 1/4 recommended dilution. Thorough flushing with clear water every month is recommended to prevent buildup of fertilizer salts.

POTTING is necessary when 1) the rhizome of the plants protrudes over the edge of the pot, or 2) the potting medium starts to break down and drain poorly (usually after 2 to 3 years). It is best to repot 1) just before new roots sprout from the rhizome, 2) after flowering, or 3) in the spring time.

Mature cattleyas are usually potted in medium-grade potting material; seedlings in fine-grade. Until a plant has six mature pseudobulbs, it generally should be put into a larger pot and not divided. If dividing a plant, 3 to 5 bulbs per division are required. Select a pot that will allow for 2 to 3 years of growth before crowding the pot. Place a small cone of potting material in the bottom of the pot, cut off any rotten roots, and spread the firm, live roots over the cone. Fill the pot with medium, working it around the roots. Pack firmly; stake if necessary. Keep the plant humid, shaded and dry at the roots for a while to promote new root growth. A vitamin B1 solution may help re-establish plants quickly.

Prepared by: Education Committee, American Orchid Society

These orchids are prized for their sprays of large flowers, used especially as cut flowers or for corsages in the springtime. There are two main types of cymbidiums - standards and miniatures. Where summers are warm (above 90 degrees F), only miniatures are recommended, because they are more heat- tolerant and bloom in warmer weather.

LIGHT is very important for growing cymbidiums. Coming from cool and bright areas in Asia, they need high light but cool temperatures. In many of our climates, the high level of light cymbidiums need is accompanied by high temperatures in the summer, which may cause the plants not to bloom. There are several ways to counteract this: spray the plants with water during summer afternoons to cool the plants down, shade more heavily and increase air movement. The maximum amount of light possible, short of burning, should be given to the plants. This means only light shade during the middle of the day, or about 20% shade. In cool areas (e.g., coastal California), full sun is tolerated. Leaves should be a medium to golden green in color, not dark green. Shade more in the winter, especially if in bud.

TEMPERATURE is the most critical factor in blooming cymbidiums of either type. During the summer, standard cymbidiums are usually grown outside in semi-shade, where day temperatures should be 75 to 85 degrees F (or more), but night temperatures in the late summer to fall (August to October) must be 50 to 60 degrees F to initiate flower spikes. Optimum temperatures in winter are 45 to 55 degrees F at night and 65 to 75 degrees F during the day. When in bud, temperatures must be as constant as possible, between 55 and 75 degrees F. Miniatures can stand temperatures 5 to 10 degrees higher than standards and still bloom well. Most cymbidiums can stand light frosts and survive, but it is not recommended. Bring them inside when temperatures dip to 40 degrees F; in mild climates they may be grown outside year-round. A bright and cool location inside is best for winter months.

WATERmust be provided at all times to cymbidiums. As semi- terrestrials, they need a fairly constant supply of moisture. Since they produce all their vegetative growth during the spring and summer months, they need the most water then. Water heavily during the growth season, keeping the potting medium from drying out completely, and reduce water when the pseudobulbs are completed in late summer. Keep barely moist during the winter.

HUMIDITY outdoors is usually sufficient during the summer months, except in dry climates. There, evaporative cooling in a greenhouse, or misting outside, is necessary. Keep humidity at 40%-60% during the winter, especially if plants are in bud. Keep the air moving to prevent fungus(Botrytis) from spotting the flowers.

FERTILIZING at the proper time will help cymbidiums bloom. During the growth season (spring through late summer), high- nitrogen fertilizer (like 30-10-10) is used. In late summer, use a high-phosphorus, bloom-booster fertilizer (like 10-30- 20), to help form bloom spikes. Fertilize at full strength every week to two weeks. In winter, fertilize once a month.

POTTING is usually done in the spring after blooming, usually every two years or when the potting medium decomposes. Shake all the old potting mix off the roots, dividing the plant if desired. Divisions of green bulbs with leaves must have 3 to 4 bulbs minimum to bloom; bulbs without leaves are considered backbulbs, and need special care to grow (see below). Pick a potting mix that will hold moisture well; a medium-grade fir bark with peat moss and perlite is a common mix. Select a pot that will allow for at least 2 to 3 years of pseudobulb growth before crowding the pot, while planning on placing the active growing bulb(s) of the division farthest from the side of the pot. Spread the roots over a cone of the mix in the bottom of the pot, and fill the pot with medium, working it among the roots, tamping firmly. The junction of roots and pseudobulbs should be about 1/2" to 1" below the top of the mix. Keep shaded, drier at roots but humid, until new roots grow.

Backbulbs may be left on the division to add strength, or removed to propagate. Take single backbulbs, and bury halfway in a bark or peat/sand mix. Keep shaded and warm until new growth sprouts, and pot as above. It may take up to three years to produce a blooming-size plant from this method.

Prepared by: Education Committee, American Orchid Society

CALLISTA - Most are bulbous plants with a pendant inflorescence.Species: aggregatum, chrysotoxum, densiflorum, farmeri, thyrsiflorum, etc. CULTURE: Summer - give warmth (60 to 90 degrees F), medium light, medium quantities of water and fertilizer. Winter - cool (50 degrees F nights), medium light, just enough water to keep bulbs from shriveling, no fertilizer.

SPATULATA (antelope-type) - Evergreen for several years. Most are large, vigorous plants with long-lasting blooms in summer to several times a year.Species: antennatum, canaliculatum, discolor, gouldii, johannis, lineale (veratrifolium), stratiotes, strebloceras, taunnum. CULTURE: Warm all year (55 to 60 degrees F nights, 65 to 90 degrees F days); no rest period; can be kept cooler in winter if dry; medium to high light.

DENDROBIUM - Most plants pendulous, leaves all along canes. Flowers 2-5 per inflorescence, from upper nodes of leafless canes.Species - Group 1: chrysanthum, friedricksianum, nobile, wardianum.Species - Group 2: anosmum, crassinode, falconeri, fimbriatum, findlayanum, heterocarpum (aureum), loddigesii, moniliforme, parishii, primulinum, transparens. CULTURE - Group 1: Growth period in summer - give warmth, water, and fertilize heavily from when roots appear until top leaf appears on canes. Then give higf light, little to no water, no fertlizer, cool nights (40 to 50 degrees F). In other words, forget about them! CULTURE - Group 2: Same as Group 1, but winter nights 55 degrees F. Deciduous species need virtually no water in winter.

LATOURIA - Leaves at top of pseudobulbs are large and leathery, inflorescence erect, flowers commonly yellow-green. Species: atroviolaceum, macrophyllum, spectabile, etc. CULTURE: Same as antelope-types, but cooler and drier when resting in winter.

FORMOSAE - Cane-like pseudobulbs, with black hairs on leaf sheaths and pseudobulbs often apparent. Flowers usually white, up to 4" across, 2 to 3 together from near the end of the pseudobulb. Species: bellatulum, dearii, draconis, formosum, infundibulum, lowii, lyonii, margaritaceum, sanderae, schuetzii. CULTURE: Intermediate to cool year-round 50 to 60 degrees F nights, max. 85 degrees F days. Water and fertilize when growing; give a slight short rest (dry) when growth is completed. Keep barely moist until growth starts again.

PHALAENANTHE - Evergreen for several years, with thin, tall pseudobulbs, terminal inflorescences, usually appearing in fall or twice a year (see culture).Species: affine, bigibbum (phalaenopsis), dicuphum, williamsianum. CULTURE: Grow warm year-round (see below); 60 degrees F nights; water and fertilize heavily when roots appear from new growth; low to medium light; reduce water and fertilizer after growth finishes. If a short (3 to 4week) cooler (55 degrees F), dry rest is given, and then plants are warmed again (60 degrees F min.), another growth may mature during winter and bloom in spring. Treat this growth as a summer growth cycle. These grow well with phalaenopsis, except for the rest period. If you must keep plants cool in winter, keep them bone dry until weather warms, then water as growth appears. Plants will go deciduous with this cool/dry treatment.

Prepared by: Education Committee, American Orchid Society

This genus produces large, showy triangular flowers that are waxy and long-lasting. The plants are distinctive for their roundish bulbs and broad, plicate(pleated) leaves. Two cultural groups are generally recognized -- the evergreen skinneri type, that flowers from leafy pseudobulbs, and the deciduous aromatica type, that flowers from leafless pseudobulbs. Culture for the hybrid genus Angulocaste(Lycaste x Anguloa) follows the curture for the Lycaste parent.

LIGHT requirements vary. Deciduous species prefer light conditions as for cattleyas 2,000 to 4 000 foot-candles or 50% to 70% shade. More light is usually provided as new growths form pseudobulbs. Evergreen species prefer less light, 1,500 to 2,000 foot-candles or 60% to 80% shade.

TEMPERATURE for the evergreen species should be fairly constant and never hot. Nights of 52 to 58 degrees F and days of 65 to 78 degrees F are desirable. The deciduous species of Lycaste can tolerate a wider range, up to 95 degrees F during the day and down to 50 degrees F at night when dormant in the winter.

WATER should be applied in larger amounts during, active growth (usually summer) than when the plants are not producing new leaves and pseudobulbs. The potting medium should just begin to dry out before watering. Deciduous species should be kept almost completely dry when leafless; evergreen species should be kept only slightly drier than normal after pseudobulbs form. Water should be kept off the leaves, and especially out of new growths, to prevent rot or leaf spotting.

HUMIDITY should be maintained at 40% to 70%. Deciduous species need less humidity when dormant. Brisk air circulation will help prevent damage to leaves by leafspot fungi.

FERTILIZER should be applied regularly and heavily when plants are actively growing. A high nitrogen formulation (30-10-10) is recommended during active growth (usually summer); some growers top-dress the potting medium with blood meal as new pseudobulbs form. In fall, or as growths mature and pseudobulbs are produced, fertilizer is reduced and/or switched to a high phosphorus (10-30-20) formulation to stimulate flower production.

POTTING is best when new growth starts, usually in spring. A fine-grade potting medium is often used; fir bark and perlite (3:1) is a common, well-draining mix. When repotting, split plants into no less than two bulbs per pot and choose a pot to allow for two years of growth. The bottom one quarter to one third of the pot should be filled with drainage material, either broken crock, rocks, or Styrofoam "peanuts". The plant should be positioned in the pot so that the newest growths are farthest awayfrom the edge of the pot, allowing the maximum number of new growths without crowding the pot. Spread the roots over a cone of potting medium and fill in around the roots with potting medium to the junction of the roots and the pseudobulbs. Firm the medium well around the roots by applying pressure. Keep humidity high and the potting medium on the dry side until new roots form. A vitamin B1 compound may help establish newly potted plants.

Prepared by: Education Committee, American Orchid Society

Masdevallia, a genus of some 350 species usually from cool, misty mountains of the New World tropics, is known for its showy flowers with sepals striking in their size, shape, and/ or color. Their need for a cool, damp environment makes them an excellent choice for cool, coastal climates.

LIGHT levels for this group usually are thought of as fairly low; however, some successful growers believe that the best flowerings are produced under higher light levels. Plants can be grown, but not necessarily flowered, in the same light levels as those for ferns -- 400 to 1,000 foot-candles. Most growers maintain levels adequate for Phalaenopsis and Paphiopedilum -- 1000 to 1,500 foot-candles. Masdevallias can be kept in light intensities up to 2,500 foot-candles if the growing area can be kept cool. Plants grow well under four- tube fluorescent fixtures and can be summered outside in shade.

TEMPERATURE should be cool to intermediate; plants will grow slowly and eventually expire if temperatures remain high for long periods of time. Cool evenings help reduce heat stress during the day. Nights of 50 to 55 degrees F are ideal; day temperatures should be 60 to 75 degrees F. Evaporative cooling pads or humidifiers are useful in maintaining these conditions.

WATER is critical for these plants because they have minimal water storage tissue. Roots should be allowed to become just dry before watering again if drainage is adequate, constantly moist roots are fine.

HUMIDITY is important for these plants. The ideal range is 60% to 80%. In the home, mist the plants (in the morning only) and set the plants on trays of gravel, partially filled with water. In the greenhouse or enclosed growing area, humidity can be increased by misting or wetting down the floors, while evaporative coolers help raise humidity and lower temperatures. If plants are summered outdoors, automatic misters under the benches are recommended.

FERTILIZER should be applied regularly while plants are actively growing. Applications of 30-10-10 type formulations twice a month are ideal for plants in a bark-based medium. A 20-20-20 type formulation should be used for plants in other media. If weather is dull, applications once a month are sufficient. Some growers use a high phosphorus, 10-30-20 type formulation (bloom booster) as plants approach flowering.

POTTING is best done in the winter or early spring, before the heat of summer and/or as new roots are produced. Plants must be repotted frequently, every one to two years, to keep the potting mix from decomposing. A fine-grade potting medium, such as fine fir bark or treefern fiber, is often used with plastic pots. Sphagnum moss is also used, especially for establishing plants. The bottom one quarter to one third of the pot should be filled with drainage material, either broken crock, rocks or Styrofoam "peanuts." The plant should be positioned in the pot so that the newest growth is farthest from the edge of the pot, allowing the maximum number of new growths without crowding the pot. Plants growing in many directions may be positioned in the center of the pot. Spread the roots over a cone of potting medium and fill in around the roots with potting medium to the junction of the roots and the plant. Firm the medium around the roots by applying pressure. Keep humidity high and the potting medium slightly dry until new roots form. A vitamin B1 compound may help establish newly potted plants.

Prepared by: Education Committee, American Orchid Society

These New World Tropics, high-altitude orchids are popular where cool temperatures prevail. The Colombian miltonias (truly Miltoniopsis) and showy odontoglossums have striking sprays of flowers. Culture is similar for hybrids in this group, some being Odontonia, Odontioda and Vuylstekeara.

LIGHT levels should be bright. An east window or a shaded south window in the home is ideal; western exposures are usually too warm in most climates. In a greenhouse, levels from 2,000 to 5,000 foot-candles are acceptable; some Miltoniopsis growers demand the pink flushing in the plants' leaves which results from the high light levels. If summer day temperatures are high, light levels can be reduced to cool the growing area.

TEMPERATURE is critical for these plants; day temperatures below 75 to 80 degrees F are preferred year-round. Night temperatures of 55 to 58 degrees F are best. Short periods of warmer day temperatures may be tolerated, especially if humidity and air movement are at optimal revels and nights are cool. Miltoniopsis plants prefer night temperatures at the upper end of the range while many odontoglossums thrive at 50 to 55 degrees F at night.

WATER should be plentiful, coupled with perfect drainage. The potting medium should just start to dry before watering again. "Accordion-pleating" on miltonia leaves is a symptom of insufficient water or humidity, and may appear on plants of other genera if severe. This may mean watering every two to seven days, depending on weather, pot size and material, and type of potting medium.

HUMIDITY ideally 40% to 80%, is important for all these orchids, coupled with moving air. In the home, set the plants on trays above moist pebbles, with the pot resting above the water. Misting is beneficial, but in the mornings only. Evaporative cooling in a greenhouse increases humidity while cooling the air and is highly recommended for these orchids in most climates. Fogging the air or dampening the floor with water also helps cool and humidify.

FERTILIZER should be applied regularly while plants are actively growing. Applications of 30-10-10 formulations twice a month are ideal for plants in a bark-based potting medium. A 20-20-20 formulation should be used on other media or on slabs. If weather is dull applications once a month are sufficient. Some growers use a high-phosphorus 10-30-20 formulation bloom booster as plants approach flowering.

REPOT as new growth emerges from the base of the plant which is usually in the spring or fall. These orchids like to be very pot-bound, so when repotting leave only enough room for one to two years of new growth. A fine-grade potting medium with excellent drainage is required; since the medium is kept moist, annual or bi-annual repotting is normal. Usually the lowest one-quarter to one-third of the pot is filled with drainage material, either crock shards, rocks, or Styrofoam "peanuts." Spread the roots over a cone of potting medium and fill in around the roots with potting medium. Firm the potting medium well around the roots by applying pressure. Keep humidity high and the pot dry until new roots form. A vitamin B1 compound may help establish newly potted plants.

Prepared by: Education Committee, American Orchid Society

This varied group of orchids includes plants from many types of environments. Some come from hot and dry areas, while others grow in less severe conditions. More specific instructions may be available from the grower. Some genera included are Aspasia, Brassia, warm-growing oncidiums and miltonias (often called the Brazilian-type), and many of their hybrids.

LIGHT can be from just bright to almost full direct sun depending on the plant. Most will thrive with one to several hours of sun a day. Generally thicker-leaved plants can stand more light, such as "mule-ear" and "equitant" oncidiums. In the home, east, south or west windows are ideal. Many types will grow under artificial light: four fluorescent tubes 6 to 12 inches over the plants are necessary for proper growth. Metal- halide and sodium-vapor bulbs also provide sufficient light without needing to be so close to the plant. In a greenhouse, 20% to 60% shade is required, or about 2,000 to 6,000 foot- candles, depending on the plants grown.

TEMPERATURE for this group are generally called intermediate to warm: 55 to 60 degrees F at night, and 80 to 85 degrees F during the day. Temperatures to 95 to 100 degrees F are tolerated if humidity and air movement are increased as the temperature increases.

WATER requirements vary with the type of plant. Generally, plants with large fleshy roots and/or leaves need less frequent watering than thin-leaved and/or thin-rooted plants. Watering should be thorough, and plants should dry at least halfway through the pot before watering again. This may be every 2 to 10 days depending on weather, pot size and material, type of orchid and type of potting medium. Plants not actively growing, should be watered less; many species have winter rest periods.

HUMIDITY should be between 30% and 60%. Most of these orchids require less humidity than some other orchids. In the home, placing the plants on trays above moist pebbles is ideal. Misting the plants in the morning may help increase humidity but is usually not recommended for fleshy-leaved types. Most greenhouses have adequate humidity.

FERTILIZER should be applied regularly while plants are actively growing. Applications of 30-10-10 formulations twice a month are ideal for plants in a bark-based potting medium. A 20-20-20 formulation should be used on other media or on slabs. If skies are cloudy, applications once a month are sufficient. Some growers use a high-phosphorus, 10-30-20 formulation bloom booster as plants approach blooming.

REPOT when new growth begins from the base of the plant, which is usually in the spring. A fine-grade potting medium is usually used with fine-rooted plants and coarser mixes with large-rooted plants; the standard size is medium-grade. Usually the lowest one-quarter to one-third of the pot is filled with drainage material, either crock shards, rocks, or Styrofoam "peanuts." The plant should be positioned in the pot so that the newest growth(s) are farthest away from the edge of the pot, allowing the maximum number of new growth before crowding the pot. Spread the roots over a cone of potting medium and fill in around the roots. Firm the medium well around the roots by applying pressure. Keep humidity high and the pot dry until new roots form. A vitamin B1 compound may help establish newly potted plants.

"Equitant" and "mule-ear" oncidiums, as well as other fleshy- leaved and/or large rooted plants, can be grown on slabs of cork bark or treefern or in pots of a coarse, well-drained medium such as charcoal.

Prepared by: Education Committee, American Orchid Society

Paphiopedilums, or slipper orchids, originate from the jungles of the Far East and Indonesia. They are semi-terrestrial, growing in humus and other material on the forest floor, on cliffs in pockets and occasionally in trees. They're easy to grow in the home, under lights or in the greenhouse.

LIGHT is easier to provide for "paphsv, as we will call them, than many other types of orchids. They like shady conditions, as in the home in an east or west window, or near a shaded south window. In the greenhouse, heavy shade must be provided - - giving them about 1,000 to 1,500 foot-candles. They are often grown under the bench, provided precautions are taken to prevent rot. Fluorescent light is excellent; use 2 or 4 tubes just over the leaves.

TEMPERATURE for paphs range considerably. Many growers separate paphs into two groups, the warmgrowing mottled-leaf types and the cool-growing, green-leaf types. Warm-growing types should be 60 to 65 degrees F at night and 75 to 80 degrees F or more during the day. Cool-growing types should be 50 to 60 degrees F at night, 75 to 80 degrees F during the day. Many growers grow all plants in the same temperature range with excellent results. The plants can stand night temperatures in the 40's if necessary (as when grown outside in mild climates), as well as temperatures to 95 degrees F. Care must be taken to protect the plants from rot when cold (keep humidity low, and do not let water stand on leaves or in the crowns of the plants), and also to protect from burning when hot (shade more heavily and increase humidity and air movement).

WATER must be available at the plant's roots constantly, since they have no pseudobulbs, and therefore store most of their water in their leaves. They need a moist medium -- never soggy, but never dry. Water once or twice a week. Humidity for paphs should be moderate, between 40% and 50%, which can be maintained in the home by setting the plants on trays of gravel, partially filled with water, so that the plants never sit in water. In dry climates, misting (in the morning only) can help increase humidity. In a green house, average humidity is sufficient; spraying the floor or using an evaporative cooling system in warm climates can increase the humidity. Air movement is essential, especially when humidity is high.

FERTILIZER must be applied on a regular schedule, but care must be taken to avoid burning of the fleshy, hairy roots. High- nitrogen fertilizers (like 30-10-10) are recommended when potted in any fir bark mix. In warm weather, some growers use half-strength applications every two weeks; others use 1/4 strength every watering. It's important to flush with clear water monthly to leach excess fertilizer, which can burn roots. In cool weather, fertilizer applications once a month are sufficient.

POTTING should be done about every two years, or as the medium decomposes. Seedlings are often repotted annually. Mixes vary tremendously; most are fine- and/or medium-grade fir bark, with varying additives -- perlite (sponge-rock), coarse sand, sphagnum moss, etc. Moisture retention with excellent drainage is needed. Divide large plants by pulling or cutting the fans of the leaves apart, into clumps of 3 to 5 growths. Smaller divisions will grow, but may not bloom as well. Spread the roots over a small amount of medium in the bottom of the pot and fill with medium, so that the junction of roots and stem is buried 1/2" deep in the center of the pot. Do not overpot; an average plant should have a 4 to 6" pot.

Prepared by: Education Committee, American Orchid Society

Phalaenopsis the moth orchid, is one of the best orchids for growing in the home, and is also a favorite with greenhouse growers. Culture for Doritis, a related genus, and Doritaenopsis, a hybrid between the two genera, is the same as for pure Phalaenopsis.

LIGHT is easy to provide for phalaenopsis. They grow easily in a bright window, with little or no sun. An east window is ideal in the home; shaded-south or west windows are acceptable. In dull, northern winter climates, a full south exposure may be needed. Artificial lighting is excellent. Usually four fluorescent tubes in one fixture are placed 6" to 1' over the leaves, 12 to 16 hours a day, following natural daylength. In a greenhouse heavy shade must be given;70% to 85 shade, or between 1,000 to 1,500 foot-candles, is optimum. No shadow should be seen if you hold your hand one foot above the plant's leaves.

TEMPERATURE for phalaenopsis should usually be above 60 degrees F at night, and range between 75 and 85 degrees F or more during the day. Although higher temperatures force faster vegetative growth, higher humidity and air movement must accompany higher temperatures, the recommended maximum being 90 to 95 degrees F. Night temperatures to 55 degrees F are desirable for several weeks in the fall, in order to initiate flower spikes. Fluctuating temperatures can cause bud drop on plants with buds ready to open.

WATER is especially critical for phalaenopsis. Because they have no major water-storage organs other than their leaves, they must never completely dry out. Plants should be thoroughly watered and not watered again until nearly dry through the pot. In the heat of summer in a dry climate, this may be every other day in the winter in a cool northern greenhouse, it may be every ten days. Water only in the morning, so that the leaves are dry by nightfall, to prevent rot from occurring on the leaves.

HUMIDITY is important to phalaenopsis, the recommended humidity being between 50% and 80%. In the home, set the plants on trays of gravel, partially filled with water so that the pots never sit in water. Mist the plants in dry climates, or during dry weather, in the mornings only. Grouping plants together raises the humidity by conserving the water that plants transpire. In humid climates, as in greenhouses, it is imperative that the humid air is moving to prevent fungal or bacterial diseases. Again, leaves should be dry as soon as possible, always by nightfall.

FERTILIZER should be applied on a regular schedule, especially if the weather is warm, when the plants are most often growing. Twice-a-month applications of high-nitrogen fertilizer (30-10- l0, or a similar formulation) are appropriate in warm, humid conditions. When flowering is desired a high-phosphorus fertilizer (10-30-20, or a similar formulation) may be applied to promote blooming. Some growers apply fertilizer at 1/4 strength with every watering; this is best for warm, humid conditions. When cooler, or under dull conditions, fertilizer should be applied once a month.

POTTING is best done in the spring, after blooming. Phalaenopsis plants must be potted a well-draining mix, such as fir bark treefern, various types of stone, sphagnum moss, or combinations of these. Potting is usually done every 1 to 3 years. Mature plants can grow in the same pot until the potting medium starts to decompose, usually in two years. Root rot occurs if plants are let in a soggy medium. Seedlings usually grow fast enough to need repotting yearly, and should be repotted in a fine-grade medium. Mature plants are potted in medium-grade medium. When mature, a plant may stay in the same pot size for many years, but must have the medium changed. To repot, remove all the old medium from the roots, trim soft, rotted roots, and spread the remaining roots over a handful of medium in the bottom of a new pot. Fill the rest of the pot with medium, working it through the roots, so that the junction of the roots and the stem is at the top of the medium. Keep the plant shaded and humid, but drier in the pot, for several weeks to promote new root growth. A vitamin Bl solution may be helpful in establishing plants.

Prepared by: Education Committee, American Orchid Society

Stanhopeas bear incredible flowers with intricate and complex structures and mechanisms for pollination, from channeled "walkways" for insects, to buckets of a watery solution. Most have inflorescences that grow downward, so the plants must be potted in hanging baskets or similar containers. Flowers may be spicily fragrant, and although the flowers are short-lived, each plant may produce many inflorescences throughout the year.

Related genera, Paphinia and Peristeria, grow cooler and warmer, respectively, than others in this group, and produce upright inflorescences.

LIGHT should be bright, with direct sunlight diffused so as not to burn the leaves. Most growers suspend these orchids due to their pendulous inflorescences. This also brings the plants closer to the light. Light levels approximating those for cattleyas, or 3,000 foot-candles, are best.

TEMPERATURE for these orchids should be moderate: 52 to 60 degrees F at night, with day temperatures 68 to 75 degrees F in the winter. Plants can stand short spells of higher temperatures, but air movement, humidity and shading must all be increased. Cool night temperatures seem to promote flowering. Many species flower in the summer, and putting them outside in the summer may be ideal.

WATER in ample quantities is important to produce strong pseudobulbs and healthy flowers. Most growers pot in an open medium and water frequently, especially when warm. Dry roots lead to leaf-tip dieback, or a browning of the leaf tip. Watering frequency can be reduced in the winter months, but these plants should never dry out completely.

HUMIDITY should be kept at 40% to 75%, and at high levels especially when temperatures are high. Frequent misting reduces the chance of mite and insect infection; at the same time, strong air movement must be provided to prevent spotting of the foliage.

FERTILIZER should be applied at regular intervals. Most growers fertilize with a diluted concentration every week to two weeks. For plants in bark, use a 30-10-10 high nitrogen formulation, alternating with a 20-20-20 balanced formulation; in the blooming season, which is mainly summer, use a 10-30-20 bloom booster formulation. Plants grown in osmunda need fertilization only infrequently.

POTTING is best right after summer bloom, as most plants seem to grow year-round. Plants that rest in the winter may be repotted in the spring. The best flowerings come from large clumps of plants, so large baskets are usually used. An airy, yet moist medium seems to work best, such as medium-grade fir bark (often mixed with sphagnum peat) or osmunda fiber. Baskets are most often lined with moss before plants are placed in the medium; this allows the pendulous inflorescences to grow through the bottom of the basket. Pre-moisten the potting medium so that the roots do not dry severely after repotting. Vigorous plants may need repotting every three years.

Prepared by: Education Committee, American Orchid Society

The Vanda Alliance, as this varied group of plants is called, is made up mostly of warmth- and sun-loving orchids with very colorful flowers. Originating from tropical Asia, they are easily grown in warm climates, where plants are grown outside in light shade, such as in a lath house. In climates where winters are cold, they are often summered outside, an grown inside during the winter in a sunny window, or year-round in a greenhouse.

Related genera, Paphinia and Peristeria, grow cooler and warmer, respectively, than others in this group, and produce upright inflorescences.

LIGHT is a crucial factor in blooming some vandaceous plants. There are three types of vandas: strap-leaf, semiterete and terete. The first type has broader, flat leaves, while terete types have round, pencil-shaped leaves. The semi-teretes are hybrids between the two, with an intermediate shape. Terete types need full sun, and are best grown in high light climates. In warm, bright climates, you can grow any type of vanda, outside (if warm) with partial shade for strap-leaf types and semiteretes (especially in midday in summer) or inside (when cold) in a bright, south window. In climates where winters are dull, try strap-leaf types (or ascocendas); grow them outside in summer an in full sun inside during the winter. In a greenhouse, give the plants about 25% to 35% shade, less in winter if dull. Leaves should be a medium green, not dark green.

TEMPERATURE for most vandas should be warm; a minimum winter night temperature of 55 degrees F is recommended. Colder spells can be tolerated for a short time if it is not windy. Optimum temperatures are 60 degrees F at night, and a maximum of 95 degrees F during the day. Warmer temperatures mean faster growth, which must be balanced with higher humidity, air movement, and increased water and fertilizer. Days should be warm and humid for optimum plant growth.

WATER Vandas generally like lots of water when growing, but must dry quickly. Because of this, and their extensive root system, they are mostly grown in slatted wood baskets, or in pots with a coarse potting medium. If warm and sunny, they may need daily watering, with misting several times a day in dry or hot climates. Water sparingly in the winter or during cloudy weather, but do not allow plants to shrivel.

HUMIDITY of 80% is ideal. In tropical climates this may be easy to obtain. Yet in most climates, misting may be necessary during sunny weather. In a greenhouse, this is easier to provide by wetting down the floor, or using an evaporative cooler. In the home, place the plants on trays of gravel, partially filled with water. Do not mist the plants if the B leaves will not dry by nighttime. Air movement must be strong.

FERTILIZER a well-balanced (20-20-20) fertilizer applied full strength once a week is recommended when warm, or use 1/4 strength every watering. During cool or cloudy weather, apply fertilizer once every two to four weeks. Use a high-phosphorus fertilizer (such as 10-30-20) ever third application to promote blooming. A vitamin B1 compound may be beneficial; use it once a month.

POTTING should be done in the spring. Plants in baskets do not need to be repotted often; leave them unless the potting medium breaks down. Just set the plant, with the old basket, into a container of water to make the aerial roots more pliable, and then set plant and basket into a larger basket. For plants in pots, repot in a slightly larger pot, positioning the plant in the center. Use a coarse medium, whether fir bark, treefern, charcoal, etc., and work it around the roots. Keep shaded, humid, but drier at the roots until new root tips grow. Do not overpot.

Prepared by: Education Committee, American Orchid Society