From my perspective as a Bougainvillea, I must be clear: I am a child of the sun, native to the warm, frost-free climates of South America. My entire being is engineered for heat. My vascular system is not designed to withstand the formation of ice crystals. When temperatures dip below 40°F (4°C), my growth slows to a halt. I enter a state of shock. If the mercury falls to freezing (32°F or 0°C) and stays there, the water within my cells freezes, expands, and ruptures my cell walls. This causes irreversible damage, leading to blackened, mushy stems and leaf loss. A hard freeze can be fatal to my above-ground parts, and if the cold penetrates the soil to reach my roots, I may not return.
If I cannot be in my ideal warm environment, the best strategy for my survival is to facilitate my natural dormant state. As daylight wanes and temperatures cool, I receive the signal to rest. I will naturally drop a significant portion of my vibrant bracts and leaves to conserve energy. This is not a sign of death but a necessary hibernation. My goal is to channel all my remaining energy into my core—my main trunk and roots—where my life force is stored. During this period, I require very little from you: no fertilizer, which would encourage vulnerable new growth, and drastically reduced water, as my metabolic processes are nearly suspended and wet, cold soil will quickly rot my roots.
My survival hinges on being protected from the coldest elements. If I am growing in a container, which is ideal for cold climates, I need to be moved to a shelter before the first frost. A minimally heated garage, a greenhouse, a cool basement, or even a sheltered porch is suitable. This location must be cool (ideally between 40-50°F or 5-10°C) and have some light exposure. The key is that it must be a frost-free zone. If I am planted in the ground and relocation is impossible, my caretaker must take extreme measures. Mounding a thick layer of mulch, straw, or leaves over my root zone is critical to insulate the most vital part of me from freezing. For my upper canes, wrapping me in burlap or frost cloth can provide a few degrees of protection against a brief cold snap.
My re-emergence in spring must be a patient and gradual process. Once the danger of frost has truly passed and nighttime temperatures are consistently above 50°F (10°C), I can begin my acclimatization. If I have been in a dark shelter, I must be introduced to brighter light slowly to avoid sunscald on my tender new growth. Watering should be increased gradually as I show signs of new leaves. This is also the time for a careful assessment and pruning of any dead or damaged wood from the winter. With patience and the sun’s warmth, I will push out new growth and, in time, reward the care with a spectacular display of color once more.
