Gotcha.Right, and I’m saying, try it in the cup during that two week period where they’ve rooted but you’re deciding which is best.
Only a third of my mix is old soil, with another third being organics like worm castings and compost and to those I add flowers and such so a fresh source comes in each round.I would just keep an eye out. In a closed system, eventually the P will run out. You’ll want to refresh/amend the soil before that happens. It will likely take a while to happen but the supplies aren’t infinite