Orchids are either cool-growing, warm-growing or intermediate in their temperature needs. The nighttime temperature for cool-growing types should be about 55 degrees F, for warm-growing types about 65 degrees F, and for intermediate types about 60 degrees F. During the daytime, most orchids prefer temperatures between 65 and 75 degrees F.
The majority of orchids grow best in bright, indirect light. In the home, a south- or east-facing window is best. Protect plants from direct sun, which can burn the leaves.
Orchids need humidity above 40 percent and regular watering, but they will be damaged by too much water around the roots. When you're growing orchids as houseplants, watering them once or twice a week is sufficient.
Fertilize orchids weekly after watering. Use a soluble fertilizer, diluted according to the label instructions. Every fourth week, omit the fertilizer and flush the pot with water to avoid salt buildup.
There are more than 100,000 orchid hybrids and cultivated varieties.