I germ in moist paper towels on a saucer with a saucer on top keeping it dark and then I wrap it in a blanket and put it in a warm, high area of my house. Others germ in a shot glass of water. I don't put into rockwool until the seed pops and there is about 1/4 inch root. I then place that (with tweezers) into the rockwool cube which has been soaking in PH adjusted water so that the seed is below the top surface of the rockwool cube, rip a small piece of rockwool off the side to cover it and throw it under a T5 in a humidity dome. This method as worked for me. I place into the hydro system/grow media when I see roots poking through the bottom of the rockwool. It's important to keep the cube moist but not waterlogged.