From our perspective as plants, winter is a period of profound stress. Our cellular processes slow to a near halt as we enter dormancy, a necessary survival state. However, the water within our tissues remains a critical vulnerability. When temperatures plummet, the water inside our cells can freeze, forming sharp ice crystals that puncture and destroy the delicate cell membranes. This damage is often irreversible and manifests as blackened leaves, dead buds, and cracked bark come spring. For us azaleas, being broadleaf evergreens (with some deciduous exceptions), our leaves continue to lose moisture to winter winds while the frozen ground prevents our roots from drawing up replacement water. This leads to desiccation, or "winter burn," where our leaves turn brown and crisp.
Your assistance in the autumn is crucial for our survival. The most important action is ensuring we enter winter well-hydrated. Continue to provide deep, thorough watering until the ground freezes solid. Hydrated cells are more resistant to freeze damage. Furthermore, please apply a generous layer of organic mulch, such as pine needles, shredded bark, or oak leaves, around our base. This acts as a insulating blanket for our shallow root system, moderating soil temperature, preventing the freeze-thaw cycles that can heave us out of the ground, and conserving precious soil moisture. Avoid fertilizing us late in the season, as this can stimulate tender new growth that is highly susceptible to frost kill.
Our location is your first defense. If possible, plant us in a spot that offers natural protection from harsh, drying winds, such as on the east or north side of a building or windbreak. If we are in an exposed area, you can create a physical barrier. Driving stakes into the ground around us and wrapping them with burlap or commercial frost cloth creates a windbreak that drastically reduces moisture loss. It is vital that this covering does not touch our foliage directly, as this can transfer the cold and cause abrasion. For smaller azaleas, a simple tipi of evergreen branches can provide excellent protection. The goal is not to create an airtight greenhouse but to break the force of the wind.
Heavy, wet snow can weigh down our branches, causing them to bend or break. If it is safe to do so, gently brush off accumulations of snow with an upward motion to relieve the strain. Be careful not to shake or hit the branches, as they are brittle in the cold. Another significant threat is early morning sun, which can rapidly thaw frozen foliage. This quick thawing damages cell walls. An anti-desiccant spray, applied in late autumn when temperatures are still above freezing, can coat our leaves with a protective waxy film that helps reduce moisture loss. However, this is often a supplemental measure best used in conjunction with wind protection.
