I've started quite a bit of lettuce in small 1" grodan cubes, moving them to clay pebbles in a flood and drain hydro setup for a few weeks now. All of it doing well. In an effort to conserve rock wool I have a Question. COULD I cut these grodan cubes down in half for the seedlings to conserve rock wool? Meaning, how intensive of a substrate does a head of lettuce need for start up, since once it's a baby plant I am moving it to the clay pebbles (within 10 days). Could I cut the 1" grodan cube into a 1/2" cube, a 1/4 inch cube, etc? What is too small that it would detriment it's beginning?