there is a formula for growing(i don't know it),and the closer you come to it the better off you will be...something like...lxaxp2...light power x area x plants squared... plus mini-factors like,fan,nutrients,exact light placement,here's a photo of 4 plants under 70,000 lumins(616 watts)..and i think it can take more......and the only frets i know are on my sons guitar