This is a good read:
http://boards.cannabis.com/indoor-li...uch-light.html

But more specifically:
Quote Originally Posted by Roughrider
2000 lumens sq. ft./21500 lumens sq. m. = Absolute minimum for growth. You won't get much from this, especially after the plant has grown a bit. Not really enough to flower well.

3000 lumens sq. ft./32250 lumens sq. m. = Pretty Good growth. Enough light for the entire light cycle, although your yields may be lower.
4000 lumens sq. ft./43000 lumens sq. m. = Very good growth. Once you pass around 3500, growth rate and ability goes up fast.

Over 5000 lumens sq. ft./53750 lumens sq. m. = Optimal growth. Dense growth in all stages.
So... figure out your
Length x Width = Area
Divide your total lumens by your area
See how you stack up to the suggestion :jointsmile: