Quote Originally Posted by Mr. Ganja
What's a good rule of thumb for lumens per square feet?
your question is vague... Even though you have been answered...Did you get the answer you were looking for?
What are you asking? do you want to know the minimum lumens per sf necessary to grow under?
Or, Do you want to know how many lumens to equal the sun's Output?
what rule of thumb are you asking about?

Glad to help, but didn't know what to tell you. lw:smokin: