Pruning peonies is a maintenance practice focused less on shaping the plant for aesthetic purposes and more on ensuring its long-term health, promoting robust flowering, and preventing disease. The correct technique and timing depend entirely on the type of peony you are growing: the common herbaceous variety, woody tree peonies, or intersectional hybrids. Implementing the proper yearly care cycle is important for the perennial health and vigor of these plants, which can otherwise be susceptible to fungal issues. Understanding these distinctions is the first step toward a successful peony season.
Deadheading Spent Blooms
Removing faded flowers, a process known as deadheading, is primarily a hygiene measure performed during the blooming season, typically in late spring or early summer. This targeted removal prevents the plant from expending valuable energy on producing seeds, instead redirecting those resources to the roots for storage to support the next year’s growth and blooms. By eliminating the spent flower, you also improve the overall appearance of the plant, keeping the foliage attractive for the rest of the growing season.
To deadhead correctly, trace the flower stem down to the first set of strong, healthy leaves and make a clean cut just above this point. It is important to leave the maximum amount of foliage intact because these green leaves are necessary for photosynthesis, which is how the plant creates and stores energy for the winter. Simply snapping off the flower head is not advisable, as this leaves an unsightly stem that will eventually die back and potentially harbor disease.
Annual Cutback for Herbaceous Varieties
The most necessary annual pruning task for herbaceous peonies, which die back to the ground each year, is the complete removal of all foliage in late autumn. This cutback is not about aesthetics; it is a fundamental disease prevention strategy. Timing is important, and the cutback should occur after the first hard frost, when the leaves have yellowed or browned completely, signaling that the plant has finished storing energy for the year.
Cutting back the dead stems eliminates a major source of overwintering fungal diseases like Botrytis blight and powdery mildew, which can survive on the old foliage and reinfect the new shoots in spring. The stems should be cut cleanly down to about one or two inches above the ground, being careful not to damage the crown where the new growth buds are located. All removed material must be collected and destroyed—either by burning or disposal in the trash—and not added to a compost pile, as the composting temperatures are often insufficient to kill fungal spores.
Shaping Tree Peonies and Woody Hybrids
Tree peonies and intersectional (Itoh) hybrids require a less aggressive approach because they maintain a permanent woody structure above ground year-round. Unlike their herbaceous cousins, you should never cut these plants back to the ground, as their stems are the source of next year’s growth and flowers. Pruning for these varieties is limited to maintenance and structural adjustments.
Pruning should focus on removing dead, damaged, or diseased wood, which can be done at any time of year to maintain plant health. If light shaping is desired, it is best performed immediately after flowering, which allows the plant time to set new buds for the following year. To rejuvenate an older, unproductive tree peony, you may need to cut back a few of the oldest, thickest stems to a lower bud to encourage vigorous new shoots.
Intersectional hybrids, which are a cross between herbaceous and tree peonies, also retain a portion of their stem structure but often die back more substantially than true tree peonies. For Itohs, the annual fall cutback is typically performed, but instead of cutting to the ground, leave a few inches of stem (up to four to five inches) to protect the emerging “eyes” or buds for the following season. This minimal pruning respects the woody nature of the stem while still performing the necessary hygiene cleanup.