i just buy them from the nearest flower station, and cut them to size, theyre found everywhere. the only thing that i can point out is that the seeds or clones must not be siting in a puddle of water, but that goes to any medium as well. you cant overwater. i water according to temp/humidity and cube size. i normally cut them like 1.5"x1.5" or 2"x2" and water once every 1-2 days depending on climate. you can actually put them on timer and ebb and flow, and can be bottom fed, they wick superbly well. also they are inert with neutral ph unlike rockwool.