I've got a tray full of lettuce starts. They're just getting their first true leaves. I'm in the process of building my first coldframe. (should have it done by Monday) I'm thinking in a few more leaves I should be transplanting them to the coldframe. They're a bit leggy... not too bad, but I'm wondering about planting depth. I know with tomatoes and some other plants it's best to plant them deeper than they were, but I don't know about lettuce. What do you know about this?