Humidity Requirements of Orchids

Epiphytes and Terrestrials

• Most orchids are epiphytic, meaning that they grow attached to tree bark or a similar medium with their roots exposed. Terrestrial orchids grow in the soil. They can generally tolerate lower humidity because their roots can provide some of their needed moisture. Paphiopedilum is an example of a terrestrial orchid. Phalaenopsis, Cattleya and Dendrobium are epiphytic orchids.

Ideal Humidity

• Each variety of orchid has its own ideal humidity, which can be difficult to achieve. Orchids kept as house plants succeed because they are more flexible in their environments. Keep epiphytic orchids in an environment where the humidity is above 50 percent. Terrestrial orchids prefer humidity between 40 and 50 percent. Keep a hygrometer handy to measure the relative humidity of the micro-climate around the plant.

Dishes and Stones

• Many orchid growers sit their plants on top of stones poured into a wide, shallow dish. The grower then fills the dish with water just high enough that it does not reach the bottom of the orchid pot. When this water evaporates, it increases the humidity around the plant. The plant will still need to be watered once each week, however. If too much water drains out into the dish below, empty the excess until the pot is not sitting in water. You do not want your orchid to become waterlogged.

Misting and Humidifiers

• In homes with extremely low humidity, or for orchids with uniquely high humidity requirements, misting or the use of humidifiers are recommended. When misting the orchid, avoid spraying the crown of the plant and make sure that you do not mist it so much that the leaves cannot dry within a few hours. The same rules apply to using a humidifier -- if the plant remains wet all the time, your humidifier is set too high. Adding a small fan into the mix can help keep the air moving and evaporate excess water.