Indoor Grow Light
For indoor growing!! How many square feet will a 400watts light support plant grow?
Regular sunlight per square meter at the surface is about 350w. Depending on the type of light you're using, 400w metal halide, High Pressure Sodium, or other incandescent light will put out 360w of heat and 40w of light. Compact fluorescent lights will be 4 units, 100w each, and put out 95w (each) of light, and 5w of heat. Or you could go with 10 of the 4 foot fluoro tubes, the light and heat is the same, 95/5.
The fluoros will grow larger plants and can be kept within 1 foot of the plants at all times. The other bulbs must be at least 3 feet away, effectively cutting the total available light by 2, so only 200w is being used by the plants.
So your answer is: 1 small plant (less than 1/2 square meter total plant volume) for incandescent lights.
OR
1 large square meter volume for fluorescent lights.
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