The tree peony, cultivated first in China, offers a dramatic and luxurious floral display. This revered garden plant is highly prized for its large, often fragrant blooms and robust, shrub-like form. Understanding its nature is the first step toward successful cultivation, especially for gardeners familiar only with common peony types. This article defines the tree peony and clarifies the distinct features that separate it from its herbaceous relatives.
Structural Identity of the Tree Peony
The defining characteristic of the tree peony (Paeonia suffruticosa) is its woody stem structure that remains above ground year-round. This makes the plant a deciduous shrub, not a true tree, though it can achieve impressive size. The stems persist through winter, creating a permanent framework for new growth, unlike plants that die back to the soil.
A mature tree peony typically reaches four to seven feet in height and spread, forming a substantial presence in the garden. The foliage is often deeply lobed or dissected, giving it a finer texture than other peony varieties. This deep green foliage turns to shades of bronze and purple in the autumn, providing season-long interest.
The flowers are the tree peony’s greatest draw, with some cultivars producing blooms up to ten inches across. These magnificent flowers come in a wide spectrum of colors, including shades of yellow, purple, and apricot, which are rare in other peony types. Supported by the strong woody stems, these large, upright blooms emerge in early to mid-spring, earlier than the common garden peony.
Key Differences from Herbaceous Peonies
The fundamental difference between the tree peony and the herbaceous peony lies in their winter dormancy habit. Herbaceous peonies, such as Paeonia lactiflora, are perennials whose soft, non-woody stems die completely back to the ground when winter arrives. New shoots must then emerge from underground roots, or “eyes,” each spring.
This structural difference results in an opposite approach to maintenance, particularly pruning. Herbaceous peonies require being cut back to within a few inches of the ground in the fall to clean up dead foliage. Conversely, tree peonies should never be cut back entirely, as this would remove the permanent woody stems that produce the following year’s flowers.
The growth rate and establishment period also diverge significantly. Tree peonies are notoriously slow to establish, often following the adage of “first year roots, second year shoots, third year flowers.” While they grow slowly, adding only an inch or two of woody growth annually, they rarely require staking due to their sturdy stems.
Essential Cultivation Requirements
Successfully growing a tree peony depends on meeting its specific needs regarding sun exposure, soil composition, and planting depth. The ideal location provides full morning sun and protection from harsh afternoon sun, which can scorch the foliage and cause blooms to fade quickly. Planting the shrub in a spot sheltered from strong, cold winter winds is also advisable to prevent damage to the woody stems.
The plant requires well-drained soil and thrives in a neutral to slightly alkaline pH, as it is highly susceptible to root rot in overly wet conditions.
When planting a grafted tree peony, which is common commercially, it is necessary to bury the graft union four to six inches below the soil surface. This deep planting encourages the scion, or the desired peony variety, to develop its own root system, leading to a more robust, long-lived plant.
Watering should be consistent during the establishment phase, ensuring the soil remains evenly moist. Once established, the tree peony is quite drought tolerant, but deep watering during extended dry spells will benefit the plant. Pruning is minimal, focusing mainly on removing dead or damaged wood in late winter, and is usually limited to light shaping.
Lifespan and Mature Growth
The long-term reward of growing a tree peony is its exceptional longevity. These plants are known to live for decades, with some specimens surviving for a century or more, becoming true heirloom pieces in the landscape. This impressive lifespan makes the initial investment of time and care worthwhile for gardeners seeking enduring beauty.
Despite this long life, the growth rate remains slow to moderate, meaning patience is required before the plant reaches its full potential. A newly planted tree peony may take up to ten years to achieve a mature height and substantial width. The plant’s slow growth also means it should not be moved once established, so selecting the final planting spot carefully is paramount.