Critical Purple Rooftop Garden

Looking at one of my seedlings (the largest), I think the sun on the roof may just be too intense over a 15-hour day for these little babies. The first true leaves on that seedling have yellowed. I've brought them inside to a south-facing window so they can get a bit less sunlight for a week or so. The yellowed leaves could also be due to overfeeding, so I've cut back on the feeding for the week. Next week, the plan is to repot the seedlings into their own four-inch pots. I may have a problem with two of the seedlings because they grew very close to each other. If I can't separate them, I'll leave them together and grow them in the five-gallon grow bag. The other two should be easy to separate and later grow to maturity in three-gallon grow bags.