I read that you go by the square foot of the space? I've always used fluoros partly because less heat, i don't have that big of a space and they use less energy. not sure what the lumens rating is on the bulbs. i'll have to check think it's about 1000 or 2000 per, so 4 lights would make it anywhere from 4000 to 8000. they seem to work just fine if you get the right spectrums.
secretgarden Reviewed by secretgarden on . About how many lumens per plant? I have three plants under 18,560 Lumens, is this good? amd is this an ok light to use http://www.lowes.com/lowes/lkn?action=productDetail&productId=132655-3-24406&lpage=none ( i have a couple extra). Rating: 5