For many perennials, that is plants that come back from the ground year after year, spring is the best time of year to move or divide them. This is not so with peonies, which should be transplanted in September.

To transplant peonies, cut the top of the plant back to four inches [1]. Dig around the roots on all sides and carefully lift the clumps [2]. Shake off the excess soil and inspect the roots for any insects or lesions, discarding any damaged parts. Using a spade or a sharp knife divide the clump, allowing 3-5 buds for each new clump. Since peonies develop a deep and vigorous root system, deep soil preparation is essential. Dig the hole 18 inches in diameter and 18 inches deep, incorporating well-rotted manure or compost into the planting hole. Fill the hole with soil so that the buds of the new clump are two inches below the soil surface. Plants that are planted too deep will not bloom. Water the newly planted clumps regularly until the soil freezes, at which time a layer of mulch can be applied [3] in order to protect the new plants from sudden temperature fluctuations. It may take more than one year before the new clumps will bloom again, bringing you more of these lovely perennials.