Dividing, or propagating, peonies is a fairly easy task that should be completed in September, according to University of Illinois Extension. Peonies are hardy perennials, so they will lie dormant over winter.
Peonies don’t need to be divided to keep blooming, but if you want to multiply them, you have to divide them.
How to divide peonies
Before you begin, make sure you have a trowel or sharp spade to dig with and a place to plant your divided peonies. Peonies take full sun (at least six hours of direct sunlight each day), but they’ll tolerate some shade. The soil should drain well. Organic matter can be used to improve soil and thus peony health. Ohio State University Extension explains that peonies will survive in hardiness zones 2-8 and a wide range of soil types, but a soil pH between 6.5 to 7.5 is best.
Carefully dig 
around the peony you want to divide. The root division will likely only be several inches deep. Make sure you don’t cut any of the roots while you are digging.
Once you have dug around the root ball, lift the plant from the soil. You’ll notice the “eyes” by the roots. There should be several on each root division. These eyes are next season’s shoots, so they must face upward when you plant the peony. The eyes should only be an inch or two below the surface when planted, or else they won’t bloom. Iowa State University Extension says that peony divisions with three or fewer eyes may take two years to bloom.
If the roots of the peony are dry when you dig it up, you may want to soak the roots in a bucket of water for a couple of hours before planting.
Then, dig a hole large enough to fit the peony’s root ball. You may want to use garden soil if your dirt is poor in nutrients. If you are dividing several peonies, plant them 2 or 3 feet apart so they have room to grow. Once soil has been backfilled, water the plants.
After dividing
University of Illinois Extension recommends putting down shredded bark or pine needles as mulch in early winter.
Come spring, you won’t see peony blooms. Blooms should be full in three to four years, according to Iowa State University Extension.
If you don’t get around to dividing peonies this fall, you can divide them in spring as soon as the soil is workable.
More about fall gardening:
- Plant bulbs this fall
- How to prepare your garden for fall frost and freeze
- How to clean up your garden for fall
- September’s gardening to-do list
