did you soak the rockwool cubic in 5.5ph and medium mild nutrient solution for like 2 to 3 hours? (i use to use rockwool and oasis cubic those fucker don't work that good low success rate i recommend rapid rooters and root riot) after you cut them you would like to place them under fluorescent bulbs right away you could go to walmart get the fluorescent light for like 30 bucks, light fixture is 14.95(cheaper one for 10.00 it's white but it has no on/off swtich just plug in) and the 2 fluorescent bulbs are 6.59each(the green one comes in single tube that say plant & aquarium they work pretty good)