Thin seedlings

[oldman]

Probably better. And a few hours of full sun won't hurt them either. Even sitting in the shade on your front porch is probably better than window sill quality light indoors. But ii you want to leave them out longer, work up to longer times gradually.

As long as it's not too cool or too windy flats do fine outside. Having a flat blow over is not a happy experience. Other things to be aware of are that cats get into things they shouldn't and that even a gentle breeze will probably drying your starting mix out if you don't keep an eye on them.