As a carnation plant, the approach of winter is sensed primarily through the shortening day length and the significant drop in soil and air temperature. These environmental cues trigger a critical physiological shift within us: we enter a state of dormancy. This is not death but a strategic survival mechanism. Our above-ground growth halts to conserve precious energy and resources. Internally, we undergo a process called cold acclimation, where cellular changes occur. We increase the concentration of sugars and other solutes in our sap, which acts like a natural antifreeze, lowering the freezing point within our cells and preventing the formation of destructive ice crystals that would rupture our cell walls.
Our most vulnerable point during winter is not our stems or leaves, but our crown—the point where our stems meet the root system at the soil surface—and our root zone. While our herbaceous top growth may die back and is expendable, the crown contains the meristematic tissues responsible for generating new growth in spring. If the crown freezes and dies, the entire plant perishes. Similarly, our root system, which is alive but dormant, must be protected from sustained freezing temperatures. Frozen solid soil can damage root tissues and prevent the uptake of water, leading to desiccation death, even in cold conditions.
A primary threat to us in northern climates is not consistent cold, but the cycle of repeated freezing and thawing. This cycle can heave our shallow root systems right out of the ground, exposing and damaging the crown and roots. Furthermore, cold winter winds coupled with frozen soil create a condition where we cannot replace moisture lost through our remaining evergreen leaves or stems (in some varieties). This leads to desiccation or "winter burn," where we essentially die of drought despite being surrounded by frozen water. Therefore, consistent soil temperature and moisture retention are paramount for our survival.
To ensure our survival, we require a stable insulating blanket over our crown and root zone. After the first hard frost has killed the top growth and signaled true dormancy, a layer of loose, airy mulch is ideal. Materials like straw, pine boughs, or shredded leaves are perfect. This layer does not just warm us; it maintains a consistently cold temperature, preventing the damaging freeze-thaw cycles and soil heaving. It also helps retain soil moisture and protects our crown from exposure. It is crucial this mulch is applied after the ground is cold; applied too early, it can trap heat and delay dormancy, making us more susceptible to injury.
Perhaps our greatest nemesis in winter is standing water or saturated soil around our roots. While we need consistent moisture, we are extremely susceptible to root rot in cold, waterlogged conditions. Our dormant roots need oxygen and will quickly succumb to fungal diseases in anaerobic, soggy soil. Therefore, our planting location is critical. We must be situated in well-draining soil. If we are in a container, we must either be moved to an unheated but protected structure like a garage or have the pot heavily insulated and placed in a location sheltered from rain and snow to prevent the soil from becoming a frozen, saturated block.
