What’s important to remember here is that while the genetics of the strain you choose will have a marked impact on THC concentrations, genetics alone cannot and will not guarantee potency. You can go ahead and arm yourself with seeds capable of producing cannabis with a THC concentration of say 25%. But if you do not give your plants absolutely everything they need from day one and really go to town with your efforts, there’s every possibility you could be looking at less than half its peak THC output.