Personally, If I was going to use this light I feel a single would be fine for Early to Mid-Period Vegging. My preference would be to add a second one at the same height but separated by about 6-9inches. Bracketing or Overlapping the coverage for late vegging and flowering would increase the PAR reading at 24" and you could drop to 18-20 inches as you go into heavy flowering without loosing your side to side strength and coverage. Two lights drawing ~90watts each at the wall keeps you still at a very decent cost benefit analysis level and might even bump the yield up over double by 10-25%. Two lights would penetrate deeper and because the coverage angles would cross and add to each others reading level as distances moved away from directly under each light. I'm currently using two PS Mini's in that type of setup and very pleased with the results. BTW, IMHO with the price point currently on this light being used in this grow, it's a really great deal for the PAR results and two would still keep you under what I paid for one of my PSMIni's. Great Deal!