Peonies are beloved perennial plants, known for their abundant, fragrant blooms and longevity. To keep these plants thriving, yearly autumn preparation is necessary to help them enter essential winter dormancy. This seasonal maintenance involves cutting back the spent foliage, which promotes plant health and prevents the carryover of diseases. Proper timing and technique ensure the peony has stored enough energy for the coming year, leading to a spectacular return of flowers in the spring.
The Critical Timing for Cutting Back
The ideal time to cut back peonies is late in the autumn, dictated by specific environmental cues rather than a calendar date. Peonies must retain their foliage throughout the summer and early fall because the leaves are responsible for photosynthesis. This process creates the carbohydrates the plant stores in its roots to fuel the following year’s growth and bloom. Cutting the plant back while the foliage is still green robs the root system of this stored energy, leading to a diminished flower display the next season.
Gardeners should wait until the plant has fully entered dormancy, visibly signaled by the foliage turning yellow, brown, or showing an autumnal color shift. This change indicates that the plant has completed its energy transfer process. The most commonly recommended time is after the first hard frost, which causes the stems to collapse naturally. Removing the dead foliage at this point eliminates potential overwintering sites for fungal diseases, such as botrytis blight, which can thrive in the dead plant material.
Different Requirements for Peony Varieties
The decision to cut back depends entirely on the type of peony being grown, as not all varieties behave the same way in winter.
Herbaceous Peonies
Herbaceous peonies (Paeonia lactiflora) are the most common garden type and die back completely to the ground each year. These varieties absolutely require a full cutback in the fall to remove all spent stems and foliage.
Tree Peonies
Tree peonies (Paeonia suffruticosa) are woody shrubs that maintain their structure above ground year-round. Their stems should never be cut down, as the plant blooms on old wood, and harsh pruning will eliminate the next season’s flowers. Pruning for tree peonies is limited to light shaping or the removal of dead wood, typically done in the early spring.
Itoh (Intersectional) Peonies
Itoh, or Intersectional, peonies are hybrids combining traits of both herbaceous and tree types. Like herbaceous peonies, the stems generally die back to the ground in the fall and should be cut back. Some growers suggest leaving a few inches of stem, up to four or five inches, above the ground, especially if buds are present. This allows for annual cleanup while respecting the plant’s slightly woody structure.
The Proper Technique for Cutting Back
When cutting back herbaceous peonies, use sharp, clean cutting tools, such as hand pruners, to ensure a smooth, precise cut. Sterilizing the blades between plants with a diluted bleach solution (one part bleach to nine parts water) or rubbing alcohol is recommended. This prevents the accidental transmission of fungal spores or bacteria from one plant to the next.
The foliage should be cut cleanly near the base of the plant, leaving approximately one to two inches of stem above the soil line. This low cut removes the maximum amount of organic matter that could harbor disease. Immediately gather and dispose of all removed foliage and debris. This material should not be added to a home compost pile, as the temperatures are often insufficient to kill fungal pathogens like botrytis blight, which could then be spread back into the garden.
Post-Cut Winterizing Care
After the foliage has been removed, the final step in winter preparation is ensuring the plant’s crown and roots are protected without being smothered. The crown, where the stems meet the roots, is sensitive to excess moisture and deep burial. Young or newly planted peonies benefit most from a light layer of protective mulch, especially in regions with severe winter temperatures.
Apply a two-to-three-inch layer of a loose, breathable material like shredded bark, straw, or compost around the base of the plant. The mulch should be pulled several inches away from the crown itself, forming a donut shape. Piling mulch directly on the crown can trap too much moisture, increasing the risk of crown rot and inhibiting the plant’s ability to produce flowers the following spring. Ensuring the area is free of debris and has good drainage completes the winterizing process, allowing the peony to rest until the spring thaw.