Artificial Light for House Plants
For house plants to thrive in artificial light, they need light of a certain color, brightness and length of time.
Light color is important when plants are growing under artificial light. They need light in the blue and red portions of the color spectrum. Common incandescent bulbs don't have enough blue, so plants grown under them have long, weak stems, few leaves, and are usually pale green. Ordinary fluorescent lamps don't have enough red. Plants grown under them are shrubby and have unusually dark leaves.
Plants grown under artificial light will grow very well under a mixture of light from cool white fluorescent and incandescent lamps. A good rule is to have 30 percent of the wattage from incandescent bulbs and 70 percent from fluorescent. If you want to build your own fixture, use two 40-watt cool white fluorescent tubes and 24 watts from an incandescent source. An alternative is to buy a fixture designed especially for lighting plants.
The level--or brightness--of light required for house plants is important, too. Light is measured in footcandles, and the light in most homes seldom exceeds 100 footcandles. A few house plants can tolerate low levels of light if they're not in a dark corner. These include aluminum plants, pepperomia, most ferns, most palms and some philodendrons.
Most house plants need additional light to survive long in the average home. Older plants will shed leaves when they don't get enough light. New leaves which develop under low light conditions are smaller and thinner.
The plant growth lights which you can buy, and those you make, will provide about 800 or 900 footcandles of light six to eight inches from the source. This is enough for the African violet, avocado, geranium, cacti, gloxinia, Norfolk Island pine, orchid, poinsettia, citrus, coleus, impatiens and most succulents.
From 400 to 600 footcandles are enough for most bromeliads, jade plants, some palms, most philodendrons, piggyback plants, rubber plants, sheffleras, some succulents, zebra plants, spider plants, grape ivy, dumbcane, wax plants, prayer plants and some ferns.
Nine or 10 hours of light each day is generally enough for most house plants. But, if you are trying to get certain plants to bloom, such as chrysanthemum or poinsettia, the lighting needs are specific.
One final word on using artificial light for house plants: If you're trying only to maintain plants until you can get them back outside in the spring, lighting can be less than ideal. But if you want to keep them growing rapidly and flowering profusely, you'll have to pay attention to the quality, level or length of light specific plants need.
For more information on artificial light for house plants, contact your local county Extension office.
