There are two types of orchids which will grow well, year round, under artificial lights:

phalaenopsis (known as the moth orchid) and paphiopedilums (known as the lady slippers).

There are other orchids which will bloom under windowsill and/or artificial light conditions, but these orchids require more light than do phals and paphs.

The minimum set-up for the use of fluorescent bulbs is two 40 watt tubes. A practical set-up would alternate Gro-lux or Vita-Lite wide spectrum lights with cool white fluorescent tubes.

The lights may be left on up to 16 hours a day. Because fluorescent light produces no heat, they should be within 12" of the plants.

The optimum light for phalaenopsis is between 1000 to 1500 footcandles. Paphiopedilums, which require less light than most orchids, thrive at 800 to 1200 footcandles of light. An easy- to-use light meter should be used to measure the amount of light.

Bob Gordon, a noted author of culture books on phalaenopsis offers the following advice on the use of fluorescent light: "For phalaenopsis culture under artificial lighting with fluorescent tubes, use a fixture(s) with four of what used to be called 40 watt, 4 foot tubes. Replace the tubes May 1 and lower the tubes to 4 inches from the leaves of the plants. On October 1, replace the tubes again and lower the fixtures to about 2 inches from the leaves. The date of October 1 to replace the tubes is not arbitrary; it is chosen to kick off the flower induction process...which happens because the tubes put out a 25% or so excess above their rated capacity for a month or so during the lamp's burn-in period...just right to initiate flower induction. If a mature, healthy phal does not flower in its season, the reason is very likely lack of light, either in intensity or duration. Under lights, vary the duration from 8 hours on December 21st to 12 hours on June 21st in the Northern Hemisphere. The 2 to 4 inches will handle the needed intensity."