I'm working on my first grow -- a closet grow -- and am currently about five weeks into flowering. I'm using a 450 watt HPS bulb mounted under a reflector hood. Last night, I noticed that several leaves on one of my plants were significantly burned (crispy and brown). I'd been trying to keep the tops of the plants close to the light because of the plants' height (they're about 3' tall and I've been concerned about light reaching the bottoms). Would I be better off removing the reflector hood for the rest of this grow and letting the light bulb hang vertically in the middle of the three plants? And would that lower the temperature in the closet?
No, you deffinately would not. You need to raise your HPS to at least 18 inches above the plants and leave the hood on. If you are that worried about the bottom buds, than buy some CFLs and shine them on the bottom portion of the plants.