Dig a hole large enough for the entire root system. Place the peony plant in the hole so the eyes are 1 to 2 inches below the soil surface. Fill the hole with soil, firming the soil as you backfill, then water thoroughly. Space plants about 3 to 4 feet apart. Apply a 2 to 4 inch layer of mulch in late fall.
Straw is an excellent mulch.
Mulching will prevent repeated freezing and thawing of the soil that could damage the plants. Remove the mulch in early spring before growth begins. Transplanted peonies will not bloom well the first spring. They should be back to full flower production by the third or fourth year. Iowa State University , Ames, Iowa.