I use floros and i keep my lights like just a few inches away from the plant and i've even came in the room and my plants been touching the light for almost a full day's time or more and no sign hardly at all from burn..

I was told about 2-4" won't hurt, especially if they're meant for the purpose of only growing plants u shouldn't have to worry about it burning the leaves just keep em a little bit off the top of the plant