Well I'll never doubt the hardiness of peonies again. I bought some peonies from Costco about a month ago and since its so early and I won't be able to plant for quite awhile yet I potted them up and put them in a basement patio...unheated. I just stuck them in the dirt in 8-10 in. pots, watered them once and didn't plan on watering them again until they started to pop up. We had some cold weather well below zero for about 4 days and I forgot about the plants on the patio. I checked on them and they were frozen solid so I figured they were a loss. They unthawed about a week ago and now I can see most have started to pop up now about the soil! These were completely bareroot with just the eyes just starting to show when they were potted up so I can't believe they actually made it through that.