My seeds have just started sprouting during their germination and I am about to transplant them in to the solo cups for the first planting. I have the schultz garden safe soil for my potting mix. Should I just use that with the amount of perlite already in it or should I go buy some extra ingredients (perlite, worm castings etc.) and add them to it?
Don't put those castings or any type of fertilizer in the soil until about week three of life. Adding fertilizer, organic or not, too early, could fert burn them.