Moderately bright light (Diffused Sunlight) is preferred near a sunny East or West Window. Never in direct sunlight. Southern exposures are suitable during winter months when sunlight is less strong.

How To Care For Your Phalaenopsis Orchid
Your Butterfly Orchid Is An Easy Care Plant

LIGHT needs can vary from bright to nearly full direct sun depending on the species. Most will thrive with one to several hours of sun a day. Generally, thicker-leaved plants, such as "mule-ear" and "equitant" oncidiums, can stand more light. In a greenhouse, 20 to 60 percent shade is required, or about 2,000 to 6,000 fot-candles, depending on the plants. In the home, east, south or west windows are ideal. Many types of oncidiums will grow under artificial light: Four fluorescent tubes supplemented with incandescent bulbs and placed 6 to 10 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 plants.

TEMERATURES for this group are generally considered intermediate to warm: 55 to 60 at night, and 80 to 85 F during the day. Temperatures up to 95 to 100 F are tolerated if humidity and air movement are increased as the temperatures rise, a good general rule in any case.

WATER requirements vary with the type of plant. Generally, plants with large fleshy roots or leaves need less-frequent watering than thin-leaved or thin-rooted plants. Watering should be thorough, and the medium should dry at least halfway through the pot before watering again. This may be every two 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 between30 and 60 percent. Many oncidiums require less humidity than other orchids. Most greenhouses have adequate humidity. In the home, placing the plants above moist pebbles in trays is ideal.

FERTILIZE 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 plants in other media or on slabs. If skies are cloudy, applications once a month are sufficient.

POTTING should be done when new growth is about one-half mature, which is usually in the spring. Fine-grade potting media are usually used with fine-rooted plants an coarser mixes with large-rooted plants; the standard size is medium grade. The plant should be positioned in the pot so that the newest growth is farthest away from the edge of the pot, allowing the maximum number of new growths before crowding the pot. Spread the roots over a cone of potting medium and fill in around the roots. Firm the medium around the roots. Keep humidity high and the potting medium dry until new roots form.

Equitant and mule-ear oncidiums, as well as other fleshy-leaved or large-rooted plants, can be grown on slabs of cork bark or tree fern or in pots filled with a coarse, well-drained medium such as charcoal. This allows the drying between waterings that these types need.

PHALAENANTHE Evergreen for several years, with thin, tall pseudobulbs, terminal inflorescences, usually appearing in the autumn or twice a year (see culture). Species such as Den. affine, Den. higibbum (phalaenopsis), Den. dicuphum and Den. williamsianum.

Culture Grow warm year round (see below); 60F nights; water and fertilize heavily when roots appear from new growth; medium light; reduce water and fertilizer after growth finishes. If a short (three- to four-week), cooler (55 F) dry rest is given, and then plants are warmed again (60 F minimum), another growth may mature during winter and flower in the spring. Treat this growth as a summer growth cycle. These grow well with phalaenopsis, except for the rest period. Plants will go deciduous if grown too cool and dry.

SPATULATA (Antelope Type) Evergreen for several years. Most are large, vigorous plants with long-lasting flowers in summer to several times a year. Species such as Den. antennatum, Den. canaliculatum, Den. discolor, Den. gouldii, Den. johannis, Den. lineale (veratrifolium, Den. stratiotes, Den. strehloceras and Den. taurinum.

Culture Warm all year (60 to 65 F nights, 75 to 90 F days); no rest period; can be kept cooler in winter if dry; medium to high light.

DENDROBIUM Most of the plants are pendulous, with leaves all along the canes that most often drop with onset of cooler, drier weather. One to five flowers per node are borne from the nodes of the leafless canes in mid-winter through early spring.

Group 1 Species such as Den. chrysanthum, Den. friedricksianum, Den. nobile and Den. wardianum.

Culture Growth period in summer; give warmth, water and fertilize heavily from when roots appear until top leaf appears on canes. then give high light, little or no water, no fertilizer, cool nights (40 to 50 F). In other words, forget about them.

Group 2 Species such as Den. anosmum (superbum), Den. crassinode, Den. falconeri, Den. fimbriatum, Den. findlayanum, Den. heterocarpum (aureum), Den. loddigesii, Den. moniliforme, Den. parishii, Den. primulinus and Den transparens.

Culture Same as Group 1, but winter nights 55 F. Deciduous species need virtually no water in winter.

CALLISTA Most are pseudobulbous plants with pendent inflorescences. Species such as Den. aggregatum (now properly lindleyi), Den chrysotoxum, Den. densiflorum, Den. farmeri and Den. thyrsiflorum.

Culture Summer give warmth (60 to 90F), medium light, medium quantities of water and fertilizer. Winter keep cool (50 F nights), medium light, just enough water to keep pseudobulbs from shriveling, no fertilizer.

LATOURIA Leaves at top of pseudobulbs are large and leathery, inflorescence erect, flowers commonly yellow-green. Species such as Den. atroviolaceum, Den. macrophyllum and Den. spectabile.

Culture Same as antelope types, but cooler and drier when resting in winter.

FORMOSAE (Nigrohirsutae Type) Canelike pseudobulbs, with black hairs on leaf sheaths and pseudobulbs often apparent, leading to the popular name nigrohirsutae. Flowers usually white, up to 4 inches across, two to three together from near the end of the pseudobulb. Long lasting. Species such as Den. bellatulum, Den. dearii, Den. draconis, Den. formosum, Den. infundibulum, Den. lowii, Den. lyonii, Den. margaritaceum, Den. sanderae and Den. schuetzii.

Culture Intermediate to cool year round, 50 to 60 F nights, maximum 85 F days. Water and fertilize when growing; give a slight short rest (dry) when growth is completed. Keep barely moist until growth starts again.

OTHER SPECIES Among the popular types are Den. linguiforme, Den. tetragonum, Den. gracillimum and Den. cuthbertsonii (sophronitis).

Culture Depends on the plant's native environment. It is generally safe to grow them intermediate to warm (55 to 60 F at night), drying them out in winter (or as growth stops). Hybrids between sections vary in culture.