Peony “bulbs” are actually fleshy, tuberous roots or rhizomes that store carbohydrates for the plant. Gardeners typically lift and store these root structures when dividing the plant to propagate new ones or when moving the entire clump. Proper storage ensures the roots remain cool and dormant, allowing them to survive the winter before replanting.
When to Dig and Lift Peony Roots
The optimal time to lift peony roots is during late summer or early fall, after the foliage has naturally died back. This period, usually mid-September to late October, coincides with the plant’s natural dormancy cycle. Digging then is beneficial because the plant has finished storing energy in the roots for the next season.
Before lifting, cut all above-ground foliage back to a couple of inches above the soil line. Use a sturdy garden fork to carefully dig a wide circle, about 12 inches away from the center of the crown. Peony roots are brittle, so this wide perimeter helps avoid snapping the main storage tubers. Once the root mass is loosened, gently lift the entire clump, taking care not to damage the small, reddish growth buds, known as “eyes,” visible at the crown.
Preparing the Roots Before Storage
Immediately after lifting, rinse the root mass thoroughly with a hose to remove excess soil. Removing the soil allows clear visibility of the crown and the dormant “eyes,” which are the buds for next year’s stems. At this stage, remove any old, woody, or diseased portions, retaining only firm, healthy tissue.
If the goal is propagation, divide the root mass using a sharp, clean knife or pruners. Each new section must contain a healthy root system and at least three to five visible “eyes” for successful division. Divisions with fewer eyes will grow but take longer to produce a full display of blooms.
After cleaning and division, the roots must be air-dried or “cured” for about 24 hours in a cool, shaded location. This allows cut surfaces to dry and form a protective layer. Curing is a preventative measure against fungal diseases and rot during storage.
Choosing the Right Storage Environment
The storage environment must replicate the cold conditions roots naturally experience while preventing freezing or drying out. The ideal temperature range is a stable 35 to 45 degrees Fahrenheit (2 to 7 degrees Celsius), just above freezing. This chilling period satisfies the plant’s vernalization requirement, ensuring proper blooming in the spring. Constant temperature and high ambient humidity prevent the roots from shriveling.
Packing the Roots
To protect the roots, pack them in a slightly damp, loose medium. Suitable materials include peat moss, vermiculite, or sawdust. The packing material should feel moist, like a wrung-out sponge, but never wet, as excessive moisture promotes mold and rot.
Use breathable containers, such as cardboard boxes, paper bags, or mesh sacks, instead of sealed plastic bags which trap moisture. Place the packed roots in a dark location, like an unheated basement or root cellar, that maintains the preferred temperature range.
Check the roots monthly throughout the winter. If the packing material feels dry, mist it lightly. If mold is present, remove the affected roots and repack the others in fresh, dry medium.
Replanting After Dormancy
Replant the stored peony roots in late winter or early spring, as soon as the soil is workable after the thaw. The technique for replanting is specific and impacts future flowering success. Position the roots in the planting hole so the “eyes” face upward toward the soil surface.
The most important factor is planting depth, which must be very shallow. Cover the eyes with no more than one to two inches of soil. Planting deeper than this maximum is the primary reason peonies fail to flower, as the crown needs cold exposure to trigger bloom development. Once planted, gently firm the soil around the roots and water thoroughly.