I'm no expert in rockwool , but coincidentally ,I have 5 seedlings that I started in rockwool cubes about a week agao.I water them a little every other day and so far they are growing well. I place the cube in a net basket along with hydroton and place them in a pseudo DWC with an airstone until they get their 6th or 7th set of true leaves then if that works ,I plan to put them into my topfeed drip system.That's the plan anyway ,so far so good.