Hi lofty29

I would say a minimum of 6 inches from the plant. And check it daily because they normally get a bit of a growth spurt when you go to 12/12.
This is just advice from a beginner.
Good luck
colliefish Reviewed by colliefish on . Newbie- Lighting Question Grew my first White Widow with flouros. Switched to 12/12 now just under 2 weeks and have finaly got my hands on a 250 W HPS. Will this do for flowering and how close do i put it for max' benifit without damaging the wee girl. Regards Rating: 5