How tall are they? I would plant them and find a way to cover them to give them some protection. A pop bottle with the bottom cut and lid removed works like a small clouche when placed over plants. If it's going too low you can always put the lid back on but remove it in the daytime to let excess heat escape. Don't let the leaves touch the bottle. Even a large pot put over them at night will help. It won't freeze when it's raining.

Good luck--Batchelor buttons are pretty hardy and rather like it cool. The weather this year has not been good for gardeners. We had a big dump of snow yesterday and I'm dieing to get out in the greenhouse and get these plants out of my house

Thanks, I guess I will plant them today, as the rain hasn't started yet. I can cover them up if need be. You're right, not a good gardening year. Last year, excessive rain, this year no snow and very little rain so far. Its April and my lawn is already turning brown. So this rain (if it comes) is very much needed.