u can place cfl's as close as possible .. heres an easy way ,,, get all ur lights set up about 6 inches above ur tops ,, then stack up CD cases under your pots for height control ,, while the lights are on ,keep a little fan on ... my method is ,,, if you can fit your finger between the tops & the bulb ,, thay are too far away ,, .. insert another CD case ,, make sure they dont touch the bulb they will burn if left touching bulb for a hour or two... with close CFL's it will lead to very tight internodal spacing which is a good thing ...