Peonies are beloved garden perennials, known for their lush foliage and spectacular blooms. Whether to cut back a peony depends entirely on the variety, as different types have distinct growth habits. Herbaceous peonies die back to the ground annually, requiring seasonal cleanup, while tree peonies maintain a permanent woody structure. Understanding this difference is the first step in providing the correct care to ensure a healthy plant and abundant flowers.
Seasonal Cutback for Herbaceous Peonies
Herbaceous peonies, including the familiar garden peony (Paeonia lactiflora), die back completely once cold temperatures arrive. This annual cutback is necessary primarily for plant hygiene and preventing disease carryover. The best time for this procedure is in late fall, typically after the first hard frost causes the foliage to yellow, brown, or fully collapse.
The foliage must remain green as long as possible after blooming because the leaves continue to photosynthesize, storing energy in the root system for the following season. Cutting back the stems prematurely interrupts this energy storage process, which could result in diminished flowering the next year. Once the leaves have withered, use clean, sharp pruners to cut all stems down to about one to two inches above the soil line.
Immediately remove all pruned material from the garden area and dispose of it, rather than composting. This debris frequently harbors fungal spores, such as those responsible for powdery mildew or peony leaf blotch, which can overwinter and reinfect the plant in the spring. Removing this infected debris significantly reduces the risk of disease spread, promoting healthier growth the following season.
Pruning Requirements for Tree Peonies
Tree peonies (Paeonia suffruticosa) are woody shrubs that do not die back in the winter, so they should never be cut down to the ground like herbaceous varieties. These plants retain a permanent woody framework year-round, and their pruning needs are minimal and structural. Pruning focuses on light shaping and maintaining the overall health of the plant, rather than a full seasonal cutback.
The primary goal is removing any dead, damaged, or diseased wood, which is best done in early spring before new growth begins. Dead stems can be cut back to a healthy bud or removed entirely to the ground to encourage new growth. Heavy or aggressive pruning should be avoided, as this can easily remove next year’s flower buds, which are set on old wood.
For older, neglected plants, rejuvenation pruning can be performed by selectively removing one or two of the oldest, leggiest stems down to the ground over several years. This encourages bushier growth and a refreshed appearance without sacrificing the following season’s blooms. Tree peonies require a gentler, more targeted approach to maintain their structure and longevity.
The Practice of Deadheading
Deadheading is the practice of removing spent or faded flowers and is distinct from seasonal cutback or structural pruning. This technique applies to both herbaceous and tree peonies and should be performed during the blooming season, typically in late spring or early summer, as flowers begin to wilt. The main purpose of deadheading is to prevent the plant from expending energy on seed production.
Removing faded blooms before seed pods fully develop signals the plant to redirect energy reserves back into the root system and foliage. This stored energy supports the formation of new buds for the next spring and contributes to the plant’s overall vigor. Deadheading also improves the plant’s appearance and reduces the risk of mold or fungal development on decaying petals.
To deadhead, use clean shears to snip the flower stem just above the nearest set of healthy, full leaves. Cutting back to a set of leaves helps camouflage the remaining stem and preserves the foliage needed for continued photosynthesis throughout the summer. This simple maintenance task promotes a healthier plant and potentially more robust blooms the following year.