labifleanswered grow question 6y ago Hey gardener! We used to let the seeds open up in a glass of water and then we would put them in the rock wool cubes like that we didn't have this problem. In fact, we did have this problem but not in the cubes, we had it before moving to the cubes because whether it's soil or water, if it doesn't want to germinate, there's nothing you can do. We often ended up with 7/10. Bella ciao!