Welcome to ATP, comicalcanary. I agree with Liz, the bagged peony should do fine. I find that when I plant them in pots and give them 6-12 months to develop good roots before planting them in the garden, they do well. I have planted them directly in the garden, but those plants tend to stay small.
My Festiva Maxima that was started in a pot 2 years ago bloomed this year. Peonies Vivid and Nymph that were planted directly in the garden at the same time, are still puny plants, and no where near blooming. I bought in a bag, and started more Vivid in a pot last spring, and planted them in the fall, and they are much bigger than the plants put in the garden 2 years ago.
Best of luck with your new peonies.
