Hang with me.....
When I was a kid we used to start tobacco plants in floating rafts. I acquired a few new 256 plug floating trays "raft" and want to try to start our garden plants in them. It is basically kracky style.
Back in the day we used a steril planting medium in the trays that appeared to be peat moss, dirt and a small amount of vermiculite. I could mix it like that but I was wondering if someone can recomend a pre made mix that would work in this position.