Peonies are beloved perennials, celebrated for their large, fragrant blooms that signal the arrival of late spring and early summer. As the growing season ends, gardeners often wonder if the fading foliage requires intervention before winter. The answer depends entirely on the specific type of peony growing in the landscape. Different peony categories and their distinct growth habits dictate a specialized approach to autumn maintenance.
The Definitive Answer for Herbaceous Peonies
The most common garden variety, the herbaceous peony (Paeonia lactiflora), benefits from a thorough cutback in the fall. These plants die back completely to the ground each year, storing energy in their underground root system for the next season. The ideal time for this task is after the foliage has turned yellow or brown, typically following the first hard frost. Waiting ensures the plant has completely finished transferring its stored energy back to the roots. Cutting still-green stems too early can weaken the plant and potentially reduce the quality of next year’s bloom.
The Rationale for Fall Cleanup
Removing dead foliage in the autumn is a proactive measure centered on disease management. Peony leaves and stems are susceptible to various fungal pathogens, most notably Botrytis blight, which causes stems to rot and buds to fail. Fungal spores from diseases like Botrytis blight and powdery mildew can easily overwinter on debris left on the ground. Leaving this infected material near the plant’s crown provides a source of inoculum for the next spring’s emerging shoots. Performing a clean cutback and removing all above-ground material effectively breaks the disease cycle, significantly reducing the likelihood of infection in the following growing season.
Step-by-Step Guide to Autumn Pruning
When the foliage has fully collapsed and yellowed, use a clean, sharp pair of bypass pruners. Sterilize the tool blades with rubbing alcohol or a diluted bleach solution before and between plants to prevent the spread of spores. Make cuts approximately one to two inches above the soil line, taking care not to nick the plant’s crown, which contains next year’s dormant buds. All cut foliage must be immediately bagged and disposed of to remove the potential source of disease. Do not add the old stems or leaves to a home compost pile, even if they appear healthy, because composting may not kill fungal spores.
Handling Tree and Intersectional Peonies
The guidelines for woody peony types differ substantially from their herbaceous cousins because they do not die back to the ground. Tree peonies (Paeonia suffruticosa) develop permanent, woody stems that remain above ground and are not cut back in the fall. These shrubs set flower buds on old wood, so cutting them down would eliminate the next season’s display. Maintenance for tree peonies involves only removing dead or damaged branches; structural pruning is reserved for early spring.
Intersectional Peonies
Intersectional, or Itoh, peonies are hybrids between herbaceous and tree types. Their stems will die back like herbaceous varieties, and they require a fall cutback. They should be trimmed to about one to two inches above the soil surface to maintain garden hygiene.