40W per square foot is fine...But remember that lights intensity decreases exponentially as the distant from it increases from the plant so it is better to use more than what the plant requires as the plant may not be getting the amount of light you think.
Eclipse1203 Reviewed by Eclipse1203 on . What's the optimal watt count per square foot? My homegrown box puts out a total watt output of 107W/ft.² from 3x125W CFL. This is a CFL grow. I want to know if this is overkill since I've mylared every surface inside the box so that should increase efficiency as well as penetration. I know it should be 50W/ft.² so please tell me if 107W/ft.² is too much because even if I removed one light I'd still get a total output of 71.43W/ft.². Any advice from seasoned farmers would be nice of course. Rating: 5