What is the amount of watts you want to have per square foot??

Example Question: Is one 400w HPS enough to grow two plants within 4 sq ft.?
puff4twentynow Reviewed by puff4twentynow on . Square feet and Watts..........? What is the amount of watts you want to have per square foot?? Example Question: Is one 400w HPS enough to grow two plants within 4 sq ft.? Rating: 5