While dividing peonies is not required, Kansas State University horticulture expert Cynthia Domenghini said doing so can increase bloom production, reduce disease and provide more peony plants for the garden.
“If you choose to divide your peonies, it needs to be done this time of year,” Domenghini said.
To start dividing peonies, Domenghini said gardeners should cut the stems just above the soil surface. Next, dig up the entire root system and remove soil from the roots.
“Divide the root clump into small sections using a sharp knife,” Domenghini said. “Ensure each section has 3 to 5 buds as well as healthy roots.”
The planting location should receive sunlight at least half the day. Dig a hole large enough to fit the roots of the divided peonies so the buds will be covered by 1 to 2 inches of soil.
“Plants buried too deep may not flower,” Domenghini said. After planting, water thoroughly.
Space dwarf peonies at least two feet apart and standard peonies four feet apart. To protect the newly divided peonies in cold weather, add a layer of straw, leaves or compost after the soil freezes.
Domenghini warns that it may take a couple years for divided plants to return to full bloom productivity.
