Collard Greens

I planted several cold weather veggies under a fabric cover over the hoop house. They didn't do much so I switched to plastic. The collard greens, broccoli, cabbage, and cauliflower took off! Then the greens started bolting, and the others never produced anything but leaves. Now I read they might not because they got to warm :-( at least I got some tasty Georgia Collards and I learned a few things.