Peonies are perennial plants that emerge from a specialized, permanent underground root system, not bulbs. This structural distinction dictates how the plant stores energy, develops new growth, and how it must be planted and cared for. Peonies are often sold as “bare roots,” referring to their storage organs being dug up and sold without soil. Understanding this anatomy is the first step to successful cultivation.
Peonies Grow From Tuberous Roots, Not Bulbs
The underground structure of an herbaceous peony consists of a crown attached to thickened, fleshy storage roots. The crown is the point where the stems transition into the root system, acting as the base from which new growth emerges each spring. The crown contains bright red or pink buds, known as “eyes,” which are the dormant shoots for the next season’s foliage and flowers. These eyes must remain near the soil surface to break dormancy correctly. The attached tuberous roots function as the plant’s primary energy reservoir, storing starches and nutrients that allow the perennial to survive winter dormancy.
Distinguishing Between True Bulbs and Peony Roots
The fundamental difference between a true bulb and a peony’s root system lies in their internal composition. A true bulb, such as a tulip or daffodil, is a complete, self-contained unit made of modified leaves. Inside a bulb, fleshy, layered scales surround a central growing point, with a flattened basal plate where roots emerge. The bulb is a compact stem and leaf structure designed to hold the entire plant’s blueprint and food supply.
The peony’s structure lacks these concentric, fleshy leaf layers; instead, its storage is decentralized in the thickened roots. The peony’s crown is a portion of the stem, not a modified leaf structure, and the eyes are external buds on this stem tissue. This organization means that a peony is propagated by splitting the crown and its attached roots, ensuring each section contains several eyes and a portion of the storage roots.
Practical Implications for Planting and Care
The peony’s reliance on its crown and eyes for new growth has direct implications for planting depth. Unlike true bulbs, which are planted deep (often two to three times their height), peony crowns must be positioned very shallowly. The eyes should be covered with only one to two inches of soil. Planting the crown deeper than two inches can prevent the eyes from receiving the necessary chilling or temperature signals required to initiate flowering.
Peonies are divided in the fall by separating the crown and root mass, a process distinctly different from separating bulb offsets. Each new division must contain at least three to five eyes and a healthy mass of the tuberous storage roots to ensure successful establishment and flowering within a few years. Ensuring the correct shallow planting depth is the most important action a gardener can take to guarantee that a peony will produce its characteristic large blooms.