For houseplants to grow properly, they must have a certain color of light with the correct brightness, and must be exposed to the light for a certain amount of time. Plants need light in the blue and red portions of the color spectrum. Household incandescent bulbs lack the necessary blue color. Plants grown under incandescent bulbs have long, weak stems with very few leaves, and are usually a pale green color. On the other hand, ordinary fluorescent bulbs lack the necessary red color. Plants grown under fluorescent bulbs are usually shrubby and have dark green leaves.
Your plants will grow best under a combination of light from cool white fluorescent and incandescent bulbs. A good rule to follow is to have 30 percent of the wattage from an incandescent bulb, and 70 percent from a fluorescent bulb. For example, if you want to build your own fixture, use two 40-watt cool white fluorescent bulbs and 24 watts from an incandescent bulb. If you do not want to build your own fixture, there is an alternative method. You can buy a light fixture especially designed for houseplants. These fixtures are sold under names such as Agrolite, Vitalite, Gro-lux, or Gro-lux WS.
Usually, the light in most homes is not bright enough to grow house-plants optimally. Although plants grown with a south or west facing window will do well. However, in the wintertime some houseplants could need some additional light. Some houseplants, however, grow well under low light intensities if they are not placed in dark corners. Houseplants that can survive in low light areas include aluminum plants, the peperomia, most ferns and palms, and some philodendron. Almost all houseplants need additional light to survive over a long period of time in the average home. Older plants shed a large number of leaves when they do not receive sufficient light. New leaves that develop under low light conditions are usually smaller and thinner than leaves growing in normal light.
Commercially available "plant grow lights" and homemade light fixtures will provide as much light as a north facing window in the daytime. This type of light is adequate for most bromeliads, jade plants, the Schefflera, certain succulents, zebra plants, spider plants, the grape ivy, Dieffenbachia, wax plants, and some ferns.
Usually, 10 to 14 hours of artificial light per day are enough for most houseplants. If you want plants such as the chrysanthemum or poinsettia to bloom, light must be provided for a specific period of time. There is one last point about artificial light for houseplants. Keep in mind that if you are trying to keep your houseplants alive until they can go back outside in the spring, your lighting needs are few. If you are trying to keep your plants growing healthily indoors and flowering all the time, you must pay very close attention to the quality, level, and length of time your plants need light to ensure normal growth. When purchasing houseplants ask or find out what the light conditions are needed and if they match the location you have picked out. A change in lighting conditions is another reason why houseplants do poorly, when they are moved to a new location. Most plants are adaptable which is good for most of us.
