What is the best time to plant a Chinese tree peony?

Tree peonies set new roots when they go into dormancy in the fall. This is the time they establish their foundation and connection to the soil. In the spring, without a solid root system, tree peonies are often set back or die. They will not bloom normally in the future although they have survived. Spring planting is responsible for the reputation tree peonies have as being difficult to grow. Fall planting avoids these problems and works in harmony with the cycles of the plant for successful growth. Tree peonies planted in a pot or in burlap contained in soil can be transplanted into the ground in the spring or fall. However the plants must be potted in early fall and appropriately winterized. Otherwise they will have the same problem as bare root plants. We have tried some potted Japanese tree peonies in the spring. They died in several weeks after spring planting.