What my friend wants to know is if you can put the smaller rock wool cubes straight into the hydroton right after you put the cracked seed on them, without letting the roots show first. The only reason is that he is using the same E&F system for the whole grow so basically all he has to do is switch the lights from 18/6 to 12/12.

If this isn't possible, whats the best way to get the plant to actually sprout out of the rockwool enough to put the cube into the hydroton?