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Phalaenopsis (moth orchid), the most common household orchid, should be watered every 7 to 10 days when grown in bark-based potting media. Water thoroughly by running water through the pot for 30 to 60 seconds, then allow the bark to dry before watering again. Never let the pot sit in water. In winter with lower light, extend to every 10 to 14 days.

Phalaenopsis prefers bright indirect light (1,000 to 1,500 foot-candles or 10,000 to 16,000 lux). Direct afternoon sun burns leaves. Dendrobiums and Cattleya need more light (2,000 to 3,000 foot-candles). Paphiopedilums tolerate lower light (500 to 1,000 foot-candles). Signs of insufficient light: dark green limp leaves. Signs of excess light: yellow or reddish leaves.

Phalaenopsis prefers 65 to 85 degrees F (18 to 29 degrees C) and needs a 10 to 15 degree F (5 to 8 degree C) temperature drop at night to initiate flowering. Most orchids will not tolerate temperatures below 50 degrees F (10 degrees C). Dendrobiums and Cymbidiums tolerate cooler conditions (50 to 60 degrees F nights) and often benefit from cool treatment to trigger blooming.

The standard recommendation from the American Orchid Society is a balanced fertiliser (20-20-20) diluted to one-quarter strength, applied weekly, with a plain water flush once a month to prevent salt build-up. Alternatively, use a fertiliser formulated for orchids. Avoid fertilising a plant in bloom; resume when the bloom spike has been cut. Never fertilise a dry orchid.

Repot Phalaenopsis every 1 to 2 years when bark has decomposed (turns dark and spongy), roots are growing over the edge of the pot, or after flowering. Use fresh bark-based orchid medium and a clear plastic pot (allows root inspection). The pot should be only slightly larger than the root mass; orchids prefer snug pots. Repot in spring after flowering for best results.