Clone's i start in Cubes .
Seeds, I start in Soil Like Bio Bizz.
Only full the Pot half way up with soil,so when the seedling stretches, you an add more soil.And cover the stem.Once it starts its second set of true leaves.
I also like to put clones right up to there first set of leafs this helps with the 2 day wilt,But seedlings will all ways be easier to grow when there in soil ,but no matter how close the light is they will stretch,so half full the pot thenn once it stops stretching full inthe sides with soil ,You will find roots will come from this stem any how.
Hope this Helps Tyke