OK, here's a basic grow room question that applies to a new veg-only closet I'm setting up.
In a 2.5 x 2.5 veg closet, with 4 plants, I can use a 2-foot 8-lamp T5 light and get good results.
OK, now suppose I expand that closet to 4 x 4, but leave everything else like it was in the 2.5 x 2.5...