From our perspective, winter is not a time of death but of deep, quiet rest. We are herbaceous perennials, meaning our foliage and stems die back to the ground, but our root systems and crown remain very much alive beneath the soil. Our entire survival strategy revolves around conserving energy. We cease active growth, as the cold temperatures and reduced sunlight make photosynthesis inefficient. Our sole purpose becomes protecting our vital core—the crown and roots—from freezing solid and from rot. Being in a pot presents a significant challenge; unlike our siblings in the ground, we lack the insulating mass of the earth, making our roots far more vulnerable to rapid temperature swings and deep freezing.
The primary danger we face in a container is the freezing of our root ball. When the soil in a pot freezes, it expands. This expansion can physically damage our delicate root tissues, tearing them apart. A completely frozen root system cannot take up water, leading to desiccation—we essentially die of thirst while surrounded by frozen water. Furthermore, cycles of freezing and thawing are particularly damaging, heaving our crown out of the soil and exposing it to killing air. The second major threat is "wet feet." Soggy, waterlogged soil suffocates our roots, promotes fungal growth, and causes the crown to rot, which is invariably fatal.
Your actions in late fall are crucial for our survival. Please stop fertilizing us by midsummer; any new, tender growth stimulated now will be too vulnerable to withstand frost. As our blooms fade, you can leave the seed heads. They provide food for birds and add winter interest. More importantly, do not cut our stems all the way back in the fall. While they may look unsightly to you, these dead stems trap insulating snow and leaves, and they help mark our location. Wait until spring, when new growth emerges from our crown, to remove the old foliage.
We require a sheltered location that mimics the stable conditions of the in-ground environment. An unheated garage, shed, or cold frame is ideal. These structures protect us from the worst of the wind and extreme cold while keeping us dormant. If such a space is unavailable, please group our pots together and place us in a sheltered spot on the ground, against the north or east side of a building where we will remain consistently cold and avoid premature warming from winter sun. Insulating our pots is key. You can bury the entire pot in the ground, mound mulch, straw, or shredded leaves over and around the pot, or wrap the container with bubble wrap or burlap to buffer the roots from temperature extremes.
Even in dormancy, we cannot be allowed to dry out completely. Our roots will die if they become desiccated. Please check our soil moisture every few weeks, especially during prolonged periods without snow cover or during a winter thaw. Water us sparingly on a day when temperatures are above freezing. The goal is to provide just enough moisture to prevent the root ball from turning into a dry dust clump, not to make the soil wet. One good drink every 4-6 weeks is usually sufficient if we are protected from the elements.
