From our perspective as peonies, the need for a cold period is not a preference but a biological imperative called vernalization. Our growth cycle is hardwired to require a sustained period of chilling hours (hours between 32°F and 40°F/0°C and 4°C) to break dormancy and initiate the hormonal processes that lead to spring growth and flowering. Without this signal, our internal systems remain "asleep," resulting in weak growth, few to no leaves, and a complete absence of the blooms you cherish. In our native habitats, winter provides this naturally. In warmer zones, you must simulate it for us.
To begin this process, you must first acquire us while we are in our dormant state, typically as bare-root tubers in the fall. It is crucial that we are healthy and firm, not soft or moldy. Before our cold treatment, we require a brief period of preparation. Please soak our roots in lukewarm water for a few hours to rehydrate us after the dryness of storage. This helps us absorb moisture before our long chill and gives us a vital head start for when we are eventually planted.
There are two primary methods to provide us with the chilling hours we need, mimicking the winter we crave.
This method offers the most precise control over our environment. After hydrating us, place our bare-root tubers in a plastic bag or container filled with slightly moist (not wet) peat moss, sawdust, or potting mix. The medium should feel like a wrung-out sponge; excess moisture will cause us to rot. Ensure the bag or container has a few ventilation holes. Then, place us in the main compartment of your refrigerator, away from fruits like apples that emit ethylene gas, which can harm our buds. We need to remain at a consistent temperature between 33°F and 40°F (1°C and 4°C) for a period of 6 to 8 weeks. Please monitor us periodically for any signs of mold or desiccation.
An alternative is to plant us in large containers with well-draining potting soil immediately after hydration. Bury our eyes (the pinkish-red buds) no more than 2 inches below the soil surface. Water the pot thoroughly and allow it to drain. Then, place the entire pot inside a large plastic bag to conserve moisture and put it into the refrigerator for the same 6- to 8-week chilling period. This method minimizes root disturbance later but requires more refrigerator space.
After our artificial winter is complete, we are ready to be awakened. Carefully remove us from the refrigerator and plant us immediately in your garden. Choose a location with at least 6 hours of full sun and excellent drainage. Plant us so our growth buds are no deeper than 2 inches below the soil surface; planting too deep is a primary reason we fail to bloom. Water us in well to settle the soil around our roots. We will then respond to the warmer soil temperatures and begin to grow, having received the necessary chilling signal to produce strong stems and beautiful flowers for the coming season.
