I use floros and found a couple of my plants actually grown into the bulbs a couple of tiems and never saw any damage to leaves or otherwise. I've kept my flors about an inch off my plants for 2 months during my first grow .... penetration may be less with floros but I've had pretty good luck..... Heat hasn't been an issue in my small grow room until I added a couple of cfl........the rule of thumb is 2 inches, but....your plants can lay right on the bulb of those 40w 4 foot flos.
I use floros and found a couple of my plants actually grown into the bulbs a couple of tiems and never saw any damage to leaves or otherwise. I've kept my flors about an inch off my plants for 2 months during my first grow .... penetration may be less with floros but I've had pretty good luck..... Heat hasn't been an issue in my small grow room until I added a couple of cfl.....