Re: How far away should plants be from the light source?

The best quality light source for plants is 93,000,000 miles away (give or take a million miles), but the sun does not always meet our needs, especially for growing plants indoors. How you set up a light system for indoor plants depends on the kind of plants you are growing and what you want them to do. In general plants need the full spectrum of light to grow best. Using only incandescent lights leads to tall spindly plants because these light are lacking in the blue range. More and better fluorescent lights are being developed (usually called "grow lights" or "plant lights" or something like that). These are more expensive.

You may be able to get cheaper lights (even use incandescent lights) if you use them in conjunction with sunlight. I'll give you a site at the end which tells which houseplants grow best at which light levels. In general for artificial lighting, plants will be 2 to 3 feet from the light, so the light won't be too bright or heat up the plant (incandescent lights give off light by heating a filament and if you've ever touched one you know how hot they can be!).

For crop plants (corn, beans, etc), you can frequently tell what kind of light requirements they have by looking at the leaves. Long thin leaves or small leaves indicates adaptation to high light, and probably to heat also. Corn likes hot and high light. The larger (especially wider) the leaves, the lower the light preference, in general.

For a good site on growing plants indoors go to:

http://www.agric.gov.ab .ca/agdex/200/8502008.html

For a listing of light needs for common indoor plants:

http://hammock.ifas.ufl.edu/t xt/fairs/25214

And for a review of different types of plant lights:

http://www.geocitie s.com/RainForest/4369/fl_paper.htm