From our perspective as plants, winter is a period of immense physiological stress. Our shallow, fibrous root systems are highly susceptible to freezing temperatures, which can cause the water within our root cells to form ice crystals. These crystals can rupture cell membranes, leading to dehydration and cell death. Furthermore, our evergreen foliage continues to lose moisture through transpiration, especially on sunny or windy days. When the ground is frozen, we cannot replace this lost water from the soil, leading to a condition known as desiccation or "winter burn," where our leaves turn brown and crispy. Deciduous azaleas avoid this by dropping their leaves, but their flower buds for next spring remain vulnerable.
The most critical protection you can offer is to our roots. Applying a thick, 3 to 4-inch layer of organic mulch (like pine straw, shredded bark, or oak leaves) around our base in late fall is akin to tucking us in with a warm blanket. This layer does not generate heat but acts as a superb insulator. It buffers the soil from rapid temperature fluctuations, prevents the freeze-thaw cycles that can heave our roots from the ground, and helps retain crucial soil moisture. Ensure the mulch is not mounded against our main stem, as this can encourage rot and provide a habitat for pests.
For evergreen azaleas, our leaves need protection from harsh, drying winds and intense winter sun. A physical windbreak is immensely helpful. This can be a burlap screen erected on the windward side (usually north or west) or strategically placed on the sunny side to provide shade. The screen should break the wind without creating a damaging tunnel. Alternatively, an anti-desiccant spray can be applied to our leaves in late fall. This coating forms a thin, waxy film that significantly reduces moisture loss through the leaf surfaces, helping us conserve our internal water reserves.
Do not enter winter thirsty. A deep, thorough watering in late autumn, before the ground freezes solid, is vital for our survival. This provides a critical reservoir of moisture that our roots can slowly draw upon throughout the winter. Well-hydrated plant cells are also slightly more resilient to cold damage. Conversely, avoid fertilizing us in late summer or fall, as this can stimulate a flush of tender new growth that is exceptionally vulnerable to frost kill, wasting our stored energy on tissue that will not survive.
Our potted kin are in an even more precarious position. Their roots are completely exposed to the air temperature on all sides, lacking the insulating mass of the earth. They must be moved to a sheltered location, such as an unheated garage, shed, or against the protected foundation of your home. If left outdoors, the entire container must be heavily insulated. Grouping pots together and wrapping them with bubble wrap, burlap, or burying the pot in a mound of mulch or soil can provide the necessary buffer against the cold to keep our root ball from freezing completely.
