The fluorescent light is one of the most economical and beneficial types of artificial light for indoor plants, and therefore is a popular choice among indoor gardeners. Although incandescent light can provide the same service, fluorescent light is cheaper per hour and provides a wide spectrum of visible and invisible light that plants need. Fluorescent bulbs and fixtures may be more expensive, but given the fact that plants, especially in the shorter winter months, may need at least a few hours of supplemental light, fluorescent lights may be an economical option in the long run.
Using a broader spectrum of light is very important for some plants. Still, the Canada Department of Agriculture, in conducting experiments on the use of fluorescent lighting found that plant growth is comparable no matter what type of bulb is used. The main difference then comes down to one of aesthetics, as all lighting can encourage plant growth by providing energy for the chemical conversion process, photosynthesis.
As the practice of using fluorescent lighting for plants has grown, manufacturers have developed specific bulbs for the indoor plant grower. Now, there are compact fluorescent bulbs to use in standard light fixtures, and even special fluorescent bulbs that emphasize the blue and red ends of the light spectrum to benefit different plant types. (Blue light encourages vegetative growth and red light encourages flowers and blooming.) Normal fluorescent bulbs tend to be more heavily focused on blue light.
Fluorescent lighting also puts off much less heat than other sources, so the light can be placed closer to the plant where it can do more good. It is possible to even have fluorescent lights almost touching a plant without any problems, although that is not recommended. Generally, experts do not recommend using any light source as a plant's sole source of heat on cold winter nights. But if you do need to generate heat via lighting, using incandescent light, rather than fluorescent, would probably be the better option (there are special "heat lamp" bulbs available, which are generally available from farm-supply retailers for use in chicken brooders).
The main job of a standard fluorescent tube is to give off light in the visible spectrum. Plants use light in that spectrum, but also use light at the infrared and ultraviolet spectra, which are invisible to humans. Although the phosphors in a standard fluorescent light typically produce some invisible light, some plants may require more, depending on the situation. Some fluorescent bulbs produce light at a certain part of the spectrum or the full spectrum of light. They fit in standard fluorescent-light fixtures.
The effects of fluorescent lighting on potted plants can also be negative. One problem with fluorescent lighting is its intensity. It often is not a very intense light, although reflectors and different fixtures can help correct that problem. If the plant light is not intense enough, growth could be slowed or stunted altogether. Therefore, while fluorescents may be cheaper to operate for longer periods, if the intensity is not as great, they may not be as efficient for plant growth as some other types of lamps.