I tried using those cubes for some seeds and won't do it again, a moist paper towel then sow them an inch under the soil works great(I leave the paper towl bits in the soil to retain moisture). I had fresh seeds sprout on the 3rd day and had them popping out of the soil in about a week. The problem I've had two years in a row was the plant shedding the seed, ughhh, had one that wasn't going to happen so I had to crack it off with some scissors and it scarred the plant but eventually it recovered. The problem I found with the rockwool for seeds was it retained so much water I found the root was not reaching through the cube for water.