Plants make use of all visible light. Red and blue, however, are the most important for plant growth. The key to growing healthy houseplants is the light source. Most homes are lit with incandescent bulbs. Unfortunately, they are not a good light source for houseplants.
Incandescent bulbs emit light primarily in the red portion of the visible light spectrum.
Foliage which comes into contact with a hot incandescent bulb will be burned. Fluorescent bulbs are better sources of light for houseplants. Fluorescent tubes give off little heat and produce two and a half to three times more light than incandescent bulbs of the same wattage. They also produce light over a broader range of the visible spectrum, however, blue is predominant. In addition, they are available in square, tubular, and round shapes.