Artificial Light
Where windows with adequate light are unavailable, consider cultivating orchids beneath artificial light. Four 4-foot-long fluorescent tubes placed 6 inches apart side by side should do the trick. Two shop-light fixtures with cool-white bulbs will suffice. Special grow lights, sold under various trade names, are considerably more expensive and extend the light spectrum. The grow lights may reap better results, although data on this are conflicting. Place plants 6 to 8 inches below the tubes. Put the lights on a timer set to operate the bulbs for 14 to 16 hours a day. Many orchids, such as phalaenopsis and paphiopedilums, will be content. Orchids requiring more light, such as vandas and cymbidiums, however, need natural sunlight or high-intensity discharge lights to bloom. A fluorescent fixture in a dimly lit window adds extra light to natural sunlight, too, and can mean the difference between flowers and no flowers. Orchids that do not flower often require more light. Leaf color indicates if the amount of light is adequate. The lush, rich, dark green of most houseplants is not desirable in orchid leaves. Dark green leaves are attractive, but signal there is not enough light. A grassy green color (light or medium green with yellowish tones) means the plant is receiving sufficient light to bloom. Gauge light intensity with this simple hand/eye test: Put your hand 6 inches above the leaves and look at the shadows cast. A sharp-edged shadow means high light; a soft-edged shadow indicates medium to low light; no shadow at all means the light is insufficient for an orchid to flower. Southern- and eastern-facing windows work best for orchids; western windows canbe too hot in the afternoon; and northern ones are usually too dark. Too much direct light causes leaves to sunburn -- the leaves bleach out to white, ultimately dying and turning black -- so it may be necessary to reposition plants as the seasons change. Move plants away from or toward the window to manipulate the amount of light. A sheer curtain will cast light shade. Positioning sheets of Mylar or another reflective material in the growing area will increase usable light, a handy trick for the winter when light levels are often reduced.