Instead of just Pro-Mix add more Perlite, and some organic soil mix. I like 1/3, 1/3, 1/3 each. Water flows through like hydro. Water every 2 days. If you forget 1 day until 3 days they stay OK. Waiting for Worm Castings to arrive now. I find that if I fail to loosen the tight roots they do not spread so well. So I moisten the old soil plug to allow fraying the roots without tearing them much.