AMES, Iowa -- Peonies can thrive up to 100 years if maintained properly. Horticulturists with Iowa State University Extension and Outreach answer questions about peony care, specifically how and when to divide the plant. To have additional plant and garden questions answered, contact the ISU Hortline at 515-294-3108 or firstname.lastname@example.org.
September is the best time to transplant peonies. Begin by cutting the peony stems near ground level. Then carefully dig around and under each plant. Try to retain as much of the root system as possible.
If desired, large peony clumps can be divided at this time. Using a sharp knife, divide the clump into sections. Each division should have three to five buds and a good root system.
When replanting, dig a hole large enough to accommodate the entire root system of the peony. Position the plant/division in the hole so the buds are 1 to 2 inches below the soil surface. Fill the hole with soil and water thoroughly.
Peonies do not need to be divided on a regular basis. Peonies can be left undisturbed in the garden for 50 or more years. However, large peonies can be divided if additional plants are desired.
September is the best time to divide peonies. By September, peony plants have been able to store adequate food reserves in their roots for the following year. Also, the replanted divisions have several weeks to get reestablished at their new sites before the onset of winter.
Begin by cutting the peony stems near ground level. Carefully dig up the plants and wash or gently shake off the soil. Using a sharp knife, divide the clump into sections. Each section should have three to five buds (eyes) and a good root system. Divisions with fewer than three buds may take two or more years to flower.
When planting, dig a hole large enough to accommodate the root system of the peony. Position the peony in the hole so the buds are 1 to 2 inches below the soil surface. (Plants may not bloom well if the buds are more than 2 inches deep.) Fill the hole with soil, firming the soil around the plant as you backfill. Then water thoroughly. Space peonies 3 to 4 feet apart.
Peonies perform best in full sun and well-drained soils. When selecting a planting site, choose a location that receives at least six hours of direct sun each day. Avoid shady areas near large trees and shrubs. Poorly drained soils can often be improved by working in large amounts of compost, sphagnum peat moss or leaf mold.
Visit the Yard and Garden FAQs website at http://expert.hort.iastate.edu/ to find answers to other yard and garden questions.