Put them in pots. Can you bury the pots or will they be above ground? Main gets pretty cold so I would worry a bit about them being above ground with so little to protect them in a pot. If your garage is unheated that might be the better bet. Hopefully our more knowledgeable members will have more specific advice. Peonies are pretty tough. I kept one is a pot in our crawl space over winter. The crawl space was around 50-55F and it did just fine.
