I'm sorry, but it's just silly to be counting your ounces before they've even hatched. Spend your time and energy on something you can control. Like how happy you can make these plants. They're depending on you for survival. Talk with them, pay attention to them. Get them some modern COB lighting, or maybe Quantum Boards if those devices prove themselves.
There's so much marketing. Everyone's trying to sell their expensive fertilizers. If you're gonna stick with soil, look up ROLS. A handful of dolomite lime every once in a while, some organic tomato and vegetable fertilizer, toss in some neem meal and/or kelp meal, etc., maybe try a few compost teas. Nothing fancy or super-expensive. I agree with higgs - avoid that Miracle-Gro "time release" stuff.
I think Olive Drab is onto something when he mentioned anaerobic. Can you set those pots so that excess water escapes freely?
I'm not a fan of flushing. I did it once and caused more problems than I had beforehand.
There's no way to know how much they'll stretch when you go to flower. Genetics as well as environmental.
Are you doing anything to monitor/control pH? If you're using tap water, do you know anything about the quality? Some people say they don't worry about disinfection byproducts, but utility distribution lines can have hot spots.
