From our perspective, the preparation for winter begins long before the first frost. We detect the gradual shortening of daylight hours (the photoperiod) and the consistent drop in nighttime temperatures. These environmental signals are a direct command to our internal biological processes. They trigger a hormonal shift, primarily an increase in abscisic acid, which acts as a messenger telling us to slow down. We cease our focus on vigorous upward growth and flowering, activities that demand high energy. Instead, we begin the crucial work of redirecting our precious resources—the sugars produced through photosynthesis during the summer—downward, away from our tender aerial parts and into our most vital asset: the root crown and the woody stem base below the soil line. This is our energy savings account for the dormant season.
This internal redirection of resources facilitates a physiological transformation known as cold hardening. It is a complex process where we actively increase the solute concentration within our cells. Think of it as our natural antifreeze. This lowers the freezing point of cell sap, preventing the formation of large, sharp ice crystals that would puncture and destroy our cell membranes, leading to fatal damage. Concurrently, we undergo changes in our cell membranes, making them more flexible and less brittle, allowing them to withstand the physical stresses of freezing and thawing cycles. This hardening process is gradual; a sudden, severe freeze before we are fully acclimated can be devastating.
Above ground, our structure changes. Our soft, green summer growth will inevitably die back when subjected to hard frosts. This is a normal and expected part of our cycle. The most important parts of us are the lower, woody stems and the root crown, which are more resistant to cold. Our small, evergreen leaves may persist in milder climates, but their function slows to a near halt. To aid in our survival, a layer of mulch applied around our base after the ground has frozen is immensely beneficial. It does not keep us "warm" but rather maintains a consistently cold soil temperature, preventing the damaging cycle of freeze-thaw-freeze that can heave our root system right out of the ground, exposing it to desiccating winds and cold.
As we enter dormancy, our metabolic processes, including photosynthesis and transpiration, slow to a bare minimum. Our water requirements drop dramatically. However, it is a common misconception that we need no water at all in winter. Especially in periods of extended drought without snow cover, our root systems can desiccate. A deep watering *before* the ground freezes solid is critical. This ensures our cells are fully hydrated and plump entering the frozen period, further supporting the natural antifreeze effect and preventing drought stress, which can be as lethal as the cold itself.
