Peony

Peonies need winter cold in order to flower next year and in the ground they withstand any amount of winter frost, even though they like to be only a couple of cm below the surface.  I'm not sure about in a pot up where you are though, SC. If you have room for it in the tunnel, I would bring it in, to be safe, if you have some really cold weather, i.e. if the soil in the pot is likely to freeze solid.