Kenny, I often set up an 8' fluorescent fixture during the spring. Really, I should always do it - still, I have to decide which flats should go under it and which are okay without that extra light.

I tried to get my head around the whole foot candles, lumens, lux thing a few years ago. The bulb above my head didn't glow very bright . . . Just pulling numbers out of wikipedia this morning (and hoping they are correct ;o):

Bright Sunlight ~ 100,000 lumens.
40 watt Fluorescent Lamps (including CFL's) ~ 2,000 lumens.

The light must be kept very close to the plants, about 6" for good lighting. This can be a problem if your natural sunlight is coming in at too high of an angle - the fixture shades the plants!

For small plants and a sun at a low angle, my 8' fixtures make some sense. The larger the plants, the less sense it makes to set them up.

Commercial greenhouses commonly use high-pressure sodium vapor lamps of 400 watts. They aren't terribly expensive to purchase. And, then there are metal halide lights which are a newer way to go.

400 watt Sodium Vapor & Metal Halide ~ 36,000 lumens.

Those kind of lights would be a better choice with large plants, especially. I hope this info helps a little.

Steve

If you want production, you'll have to pay the electricity for lights. Otherwise overwintering only.

Dan

I'll just add. The two green house growers close to me said that for flavor you need the sun light hours. Like Dan stated you can get the production with lights but the flavor will be lacking. Still better than a store bought mater. Jay