I've been growing columbine flowers in my little jiffy greenhouse thing. How tall do they have to be to plant?

A few are a couple inches tall but most are just starting out. I was wondering when I can put them into the ground. I know I have to wait until the ground warms up and all, but how tall or how many leaves do they have to have first? I’m in South Carolina on the line for zone 7 and 8. Thanks!
They are dragonfly columbine’s if that makes any difference.