Many orchids are rewarding indoor plants. Once a home owner has succumbed and bought his or her first orchid, or received one as a GIFT, meeting a few cultural requirements will coax the plant to flower again. Orchids are far tougher and hardier than most people think, and are, by and large, extremely adaptable. There is a long-standing myth that orchids are difficult, if not impossible, to grow, especially without a greenhouse. With at least 20,000 species and some 100,000 artificial hybrids, there are some notoriously fussy orchids. But there are many rugged, popular, easy-to-grow types that adapt to the temperatures and light conditions found on the average home windowsill. Explore the options and assemble a collection that will put forth exotic flowers year-round. Orchids are different from other houseplants. Unlike ferns, philodendrons, palms and Swedish ivy, orchids do not grow in soil. Potting an orchid in soil is actually one of the best ways to kill it. Most orchids in the wild are not rooted in the ground, but instead attach themselves by thick roots to the sides of trees and on branches. Clinging to the bark, the plants absorb water and nutrients from the air and rain and whatever drips down the tree. They are adapted to surviving when rain is scarce, hoarding water in thick leaves, stems and roots.