The family encompasses about 6–11% of all seed plants. The largest genera are Bulbophyllum (2,000 species), Epidendrum (1,500 species), Dendrobium (1,400 species) and Pleurothallis (1,000 species). It also includes Vanilla–the genus of the vanilla plant, the type genus Orchis, and many commonly cultivated plants such as Phalaenopsis and Cattleya. Moreover, since the introduction of tropical species into cultivation in the 19th century, horticulturists have produced more than 100,000 hybrids and cultivars.
If only there was an easy guide or a little water fairy that hovered over your plants and told you exactly when and how much to water. Unfortunately, there isn't. But I think this is one of the satisfying reasons we grow orchids. It's all about balance and instinct—and plenty of patience. Here are some of the factors you need to consider when developing a watering schedule:
About 30,000 species of orchids come from all over the world, on every continent except Antarctica. As you can imagine, they come from a wide range of habitats and each type of orchid has different care requirements. Their incredible diversity also means you can always find another interesting orchid type to grow, which is one of the principal reasons the orchid hobby is so addictive!
Make sure the pot has drainage holes. You can't properly water an orchid unless it has holes through which the water can drain. Water sitting in the pot will cause the roots to rot, so it needs to be able to drain through the bottom. If you bought an orchid that came in an ornamental pot without holes, repot the orchid in one with adequate holes in the bottom. Use an orchid potting mix instead of regular potting soil.
Water thoroughly. When you do water, do it like you mean it. Different growers have different rules, but many professional growers turn on their sprinklers for 8 or more minutes. Successful home-growers sometimes dunk their plants, pots and all, into a bucket or sink of water. Some varieties, such as vandas, can be left floating in water for a surprisingly long time. The idea is to make sure the velamen is completely saturated. You want tiny droplets hanging on the roots after watering. This means the plant is completely hydrated.