I think how you grow affects potency. When your plants look ready to harvest, just wait an extra 2 weeks and that extra flowering time will make it more potent.

My last outdoor harvest was only 13 dry oz, but I got some high potency shit. I ended up with 4 females, a Mr.NiceXWhiteRhino that takes 3 tokes, a NorthernLights#5 that takes 2 tokes, and a SuperSkunk that is "One-Hit-Quit-SHIT!!!" I swear this SuperSkunk was a strange looking plant. It was far bushier than the others and all the leaves had only THREE BLADES. I never saw anything like that. It really only takes one good toke to kick my ass. If I take 2 tokes I get uncomfortably couch-locked, and I don't like that. Just one hit and quit!!!