Go ahead and plant in the ground but plant very shallow.

It will be hard to get regular peonies the number of chill hours needed to bloom every year. A tree peony would probably do better in your area. However most of the peonies shipped from China are from colder areas in China. There are peonies that are from the warmer areas of China but they are seldom imported. Please check around with your nurseries or greenhouses to see if their is anyone that imports plants of any kind from China perhaps they would order some for you.

Best of luck with your Sarah's they do well in much of the South but am not certain about your area.

You'll find some excellent information at the link below. "Sarah" is a beautiful girl so you will really enjoy your new plants.

Rosie

Here is a link that might be useful: The American Peony Society

The problem with getting enough chill in warmer winter areas like where you and I live, is the ground is a very good insulator. The winter air temperature may fall enough, but not for enough hours per night to lower the soil temperature. For this reason you should plant in the ground high enough that the buds are exposed to air temperature. It looks kind of strange to be able to see the top of the roots with the buds through the winter, but you get used to it. Sarah is a very easy to grow peony and if it has a fault it is the weight of the bloom makes it want to bow down and you may want to grow it through a grid to supply support. Al