You can have the CFL's almost touching the plant. the closer, the better.
IMO CFL's are only good for veg. Don't bother trying to flower a plant under a florescent light. If you are going to risk jail time you should just pay the extra money for a decent HID and do it properly. I have recently posted incredibly cheap HID lights from EBAY. Don't make the same mistake as me and shell out money for Weak ass flowering temp CFL's. For $300 you can have 800w HPS beaming HID glory to your 3-5 Babies. Here is my recipe for disaster.
$300 = LIGHTS (2 X 400wHPS or 1x 400w HPS + 1x 400w MH)
$150 = pots, medium, air/water pumps/fittings for 3-5 plants, airstones, power boards + extension cords.
$200 = in-line fan, duct, panda film, tape, timers.
$75 = Any veg/bloom base A+B nutes
$100 = Canna Rhyzotonic, Cannazyme, PK 13/14
$50 = CyCo; Fulvic, silica
$75 = EC/PH/Temp readers
= $1025
1xlb PER 12 WEEKS = $3200@$200 per oz
3200/12 = $266.66 pw
I only grow for personal use and calculate the lb price from my dealer, "dangerous dave's" price list. I would never sell anything, let alone a drug.