Peonies are beloved perennial flowers, famous for their lush, romantic blooms and impressive longevity. Although often referred to as a “peony bulb,” the plant is correctly started from a bare root, which is a tuberous root system with growth buds attached. These long-lived plants can thrive in a single location for decades but require specific planting techniques to ensure they produce spectacular flowers year after year.
Timing and Selecting the Bare Root
The ideal time for planting a peony bare root is in the autumn, typically from late September through the end of October, about six weeks before the ground is expected to freeze. Fall planting allows the root system to establish itself in the still-warm soil throughout winter dormancy, preparing it for vigorous spring growth. Although spring planting is possible, fall-planted peonies generally perform better and establish themselves faster.
A healthy bare root division should be firm and have at least three to five reddish-pink buds, known as “eyes,” which are the starting points for next year’s stems. Herbaceous peonies die back to the ground each winter, while tree peonies develop a permanent woody structure. Herbaceous and intersectional (Itoh) peonies require shallow planting, but grafted tree peonies must be planted deeper to encourage rooting from the graft union.
Preparing the Permanent Location
Selecting the correct site is important, as peonies dislike being moved once established. They require a location that receives a minimum of six hours of full, direct sunlight daily; insufficient light often causes a lack of blooms. The site should also be sheltered from strong winds, which can damage the large flowers and cause stems to snap.
The soil must be well-draining, as peonies quickly succumb to root rot in soggy conditions. If the native soil is heavy clay or very sandy, amend it by digging in organic matter, such as compost or well-aged manure. Dig a generous hole roughly two feet wide and two feet deep. This preparation ensures the plant has a rich, aerated environment to develop its root system.
The Planting Depth
The most important factor for success with herbaceous peonies is the precise planting depth of the eyes. These buds must be positioned facing upward and covered with no more than one to two inches of soil. This shallow placement is necessary because the buds require exposure to cold winter temperatures, a process called vernalization, to set flower buds for the coming season.
If a peony is planted too deeply, the eyes will not receive the necessary chilling, causing the plant to focus on foliage production instead of flowering. This is the most frequent cause of “blind” peonies, where the plant grows robustly but fails to bloom. To plant, build a small mound of amended soil at the bottom of the hole and spread the bare root’s long, fleshy roots out over the mound. The top of the eyes should sit at or just below the two-inch depth before gently backfilling the hole with soil.
First-Year Aftercare
Immediately after covering the bare root, the planting area needs a thorough watering to settle the soil and eliminate air pockets. Consistent moisture is important for the first year to establish a strong root system, but avoid overwatering to prevent rot. Fertilization is not typically needed if the soil was amended with organic matter, but a balanced, low-nitrogen feed can be applied early in the spring.
Gardeners should manage expectations in the first year, as newly planted peonies focus on root development and rarely produce flowers. Allow the plant to grow its foliage all season, as the leaves collect energy to store in the roots for future blooms. A light layer of mulch can be applied after the ground has frozen in late fall to prevent soil heaving during freeze-thaw cycles. Keep the mulch away from the plant’s crown.