I have mixed emotions about the peat pucks. You see, I got EXCELLENT germination out of them but for some reason I never got true leaves. I kept waiting and waiting for them to sprout true leaves before I transplanted them and it never happened so in the end I lost alot of very viable seedlings. They are easy to use and I didn't get any fungus on them like I did on some of the peat trays with starter soil. That was my fault too for overwatering them and not enough air movement. I learned alot this year growing the little guys. Ended up with about 200 seedlings that were viable. Took about 90 to work and handed them out because I was running out of space. Opps...bit off topic. Sorry
...Haven't tried rockwool but was interested in it. Let me know how and if it works out for you Grimus.