The tops seem to take the longest to root, I cloned 2. I took 15 clones from 2 different mothers and all 15 rooted. Even the underbrush that I snipped. Root Shooter are the shiznit. I just kept the humidity high by spraying the dome and keeping the tray with a little water in it. I was told not to use a warming pad for clones, did it anyway, and had no negative results.