Planted Tank Guru
Join Date: Mar 2009
Location: Madison, Wisconsin
You have to look up the blooming seasons and care requirements for each individual orchid species. They vary. Some kinds of orchids can bloom any time of the year, but most only bloom during a certain period once or twice per year. Most of the seasonal orchids also require a (usually) wintertime rest with reduced watering, cooler temps and no ferts. Many orchids also grow and flower best with cooler nighttime and warmer daytime temperatures. Fluorescent lighting is useful for this effect because the extra infrared coming from the lit-up bulbs can usually raise temps around the plants by a few degrees.
Relative humidity requirements are another important variable. Some kinds of orchids can live well in normal (as low as 30%) household humidity levels, while others require very humid air all the time or they will perish. Increased humidity is generally helpful for most kinds of orchids. Even for those species that require drying around their roots (as for a dry winter rest) it is often beneficial to have extra humidity in the air.
There are are only a few kinds of parasitic orchids and I think that all of them are terrestrial (rooted in the soil) and subsist from nutrients that they get from the roots of other plants. Most of the most popular culivated orchids are epiphytes; they are rooted on the branches of trees, but they do not take nutrients from them.