Growing them as houseplants
Most orchids require special care in a greenhouse, but more than a dozen types, including hundreds of varieties, thrive indoors if given adequate warmth, light, and humidity.
Orchids are classified according to their preferred nighttime temperatures: cool(50Fto 55F), intermediate (55Fto 65F), and warm (65F to 70F), with day temperatures 5F to 15F higher. Begin with easy-to-grow intermediates: paphiopedilums, cattleyas, and phalaenopsises (warm, but adaptable); grow coelogynes in cool, sunny rooms. Paphiopedilums are ground-growing orchids; the others are epiphytes-plants that grow perched on trees or other plants. Most epiphytic orchids have thick stems, called pseudobulbs, that rise from a horizontal rhizome.
Place orchids on a window sill with bright, filtered light; keep them out of direct sunlight except in midwinter. Orchids require at least 10, but not more than 16 hours of light daily to flower. In winter you can supplement available sunlight by placing orchids at least 6 inches under fluorescent lights for 6 hours a day or more.
In general, water orchids moderately during the growth period, allowing the top inch of the potting mix to dry out before rewatering. For cattleyas, let the mix dry out almost completely between waterings; keep coelogynes thoroughly moist during the growth period. With every third or fourth watering, apply liquid plant food diluted to half the strength suggested on the label. Water lightly and stop feeding during the fall or winter rest period.
All orchids require high humidity. Stand pots on trays of wet pebbles; don’t place them directly in water. Mist orchids two or more times a day in temperatures over 70F.
Plant ground growers in standard pots; use a mix of equal parts top soil, shredded fir bark, peat moss, and coarse perlite. Attach epiphytes to a piece of rough bark or tree-fern stem, or grow them as shown in a mix of 7 parts shredded fir bark, 1 part peat moss, and 1 part coarse perlite.
Repot orchids every 2 years in the spring. Cut off dead roots; carefully remove any clinging potting mix. If the plant has a rhizome, place it on top of the potting mix, with the oldest pseudobulb near the rim of the pot and the growing point toward the middle. Pack potting mixture around the feeding roots.