i bought a bag of professional potting mix without any ferts in the soil so do i have to start feeding a 20-20-20 right away or do i still wait for the first o0r second pair of leaves? i dont know exacly what isin the mix because the greenhouse i bought it from makes there own mix to sell.
you should still wait 10-14 days i believe since the cotydylons, the set of feeding leaves, have stored food in them.
Yep, wait until about two weeks and then start feeding at 1/4 strength, increasing strength with subsequent feedings.