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.
Consider your climate. The frequency with which you water orchids is affected by the level of humidity in your climate, as well as the amount of sun the orchid gets and the temperature of the air. Since these factors vary according to region and household, there's no rule for how often to water an orchid. You'll have to develop a routine catered to your specific environment.
The quality of water used, whether for spraying or watering, is of great importance. Since tap water has often been chemically treated, generally with chlorine, it should be used with caution. The best water for orchids is undoubtedly rainwater. Rainwater, as it passes through the air, dissolves and absorbs many substances such as dust, pollen and other organic matter. This enriched rainwater contributes to the nourishment of the plant.
These orchids can be planted in orchid bark, moss or a mix (mixes might include bark, small rocks, moss, sponge rock, and even cork). Don’t even think about planting them in the soil. If your orchid is planted in bark you’ll need to water it more often than if it’s planted in moss. The bark will help the water drain with ease where the moss will hold the moisture longer. I prefer the bark or mixes which are predominantly bark because the watering is much easier for me to get right.
Cymbidium carry tall stems with many flowers that have a more typical orchid shape. They are easily identified by their grassy leaves, and they readily form large clumps. Most common are the cool-flowering types, which need to experience a cooler winter (nights in the 40s for some time in the fall) in order to initiate flowering. Once the flowers open, they can last for up to two months or more, especially in a cool environment. These are very showy and rewarding plants, and a plant in a six-inch pot can carry three stems with 15 or more flowers each, depending on the type.
Run the orchid under water. The easiest way to water an orchid is to hold it under a faucet and run it under room temperature water. If you have an attachment that allows you to diffuse the water, rather than just running it in one strong stream, that's better for the orchid. Water the orchid this way for a full minute, allowing the water to seep through the pot and come out the holes in the bottom.
I wish I could tell you exactly how often to water your phalaenopsis orchids and how much water to give them and be done with this post. Unfortunately, there is no one size fits all answer. When it comes to watering any plants there are lots of factors to consider that’ll make the amounts and regularity vary. I’ll go over all those factors so you can see what will be the best for your own situation.