Now is the time to plant and prepare peonies to produce beautiful spring blooms. Peonies can be left undisturbed in the garden for several years, anywhere from 3-10 or more, before requiring division. However, plants that have stopped flowering or have developed a dead spot in the center are in need of division. Also, as a landscape grows and matures producing more shaded areas, full sun perennials like peonies may need to be relocated. The best time to divide or move peonies is September.
It is important to pick a planting site in full sun with well-drained soil. More than two or three hours of daily shade or poor drainage can prevent peonies from blooming. The site should be prepared two to four weeks before planting by spading organic matter into the site and adding a handful of garden fertilizer to the soil.
To divide or move peonies, first cut down the existing foliage. Carefully dig around and under the plant crown, avoiding damage to the thick, fleshy roots, and trying to retain as much of the root system as possible. Immediately replant peonies to be moved, into a full sun area with good drainage.
To divide peony clumps, gently shake the root ball to remove some of the soil. Carefully divide the clump into sections with at least three to five eyes each and a good section of root system. New growth develops from the tuber's buds, or eyes and divisions with three to five eyes bloom sooner than those with fewer. Dust all cut surfaces with a fungicide, such as Captan, to discourage infection and rot.
Dig the planting hole wide enough for the entire root system. Don’t bend or force the roots to fit into a too-small planting hole. Space plants about 3 feet apart. Place the plant in the hole so that the uppermost eye is no more than 1-2 inches below the natural soil surface. Planting the tubers too deep can prevent flowering. Add soil around the tuber to fill the planting hole, and water to settle the soil the roots.
After dividing or moving a peony, water as often as necessary to keep the soil moist. This helps the plant re-establish its root system. Consider applying a 2-3 inch layer of organic mulch in late fall to prevent frost damage to the roots. Mulch also helps conserve summer moisture. Newly transplanted peonies will not bloom well the first year, but should be back to full flower production by the third or fourth summer after division.
In established plantings, an application of fertilizer can help increase flower size. Work a handful of fertilizer into the soil around first-year plants before new shoots emerge. Older plants should be fertilized when flower buds are pea-sized.
SOURCE: Don Janssen, Extension Educator, Lancaster County, NU/IANR
