I've done CFL's a few times in the past for seedlings. It doesn't take much, so dependending on your wattage; you could be fine. A 80 or 100W equivalent about 6 to 9" off the top should be good. The only time I had problems was when they were in a confined space, and made things too hot. Don't fry them like I did! Lol. That's when I changed to a few 5-6k screw-in LED's.