So, 2 square feet? I think a 400 watt light is overkill for that little area. You'd be better off getting four 42-watt (real watts, not equivalent) CFLs. That'd give you about 4500 lumens per square foot, which is plenty, and it'd be cheaper to run and much cooler. You really just need more area though; even one plant will get cramped in that small area.