It all depends on your temperature and other weather conditions when they bloom. If you are lucky, no heavy rain, winds, and low temps perhaps a week. The bloom time could be as short as a day. Both are floppy so you will need to provide some support.

Since most peonies are planted in the fall now is a good time to start investigating what you want and to prepare a planting space for the plants. You never will just plant one peony.