As the days shorten and the air cools, my internal biological clock begins to tick differently. I, a Calibrachoa, sense the diminishing light and lower temperatures. My vibrant flowering, which was so prolific in the long, warm days of summer, starts to slow. This is not a sign of weakness, but a natural response. My energy is shifting from prolific blooming and vegetative growth to preservation. The sugars I produced through photosynthesis are now being directed to my core structures—my stems and root system—to build up reserves for the challenging season ahead. I am preparing for dormancy, a period of rest, not death.
To successfully accompany me through the winter, you must assist in this energy conservation. Before the first hard frost threatens, please prune my stems back significantly. Remove about half to two-thirds of my growth. This might seem drastic, but from my perspective, it is a tremendous relief. It drastically reduces the amount of leafy tissue I need to sustain through the low-light winter months. With less foliage, I lose less water through transpiration and can focus every bit of my stored energy on simply staying alive, not supporting excessive growth. This pruning also helps remove any tender, new growth that would be highly susceptible to cold damage and disease.
I cannot survive freezing temperatures. My ideal overwintering location is a sheltered environment that is cool but never freezing—a consistent temperature between 40-50°F (4-10°C) is perfect. A cool garage, a basement with a window, or an unheated sunroom are excellent choices. This coolness is crucial as it keeps me properly dormant. If I am kept too warm, I will be tricked into attempting weak, spindly growth that depletes my energy reserves under insufficient light. The location should also be bright; a south-facing window is ideal. While I require far less light than in summer, some light is essential for basic photosynthetic function to keep my core leaves green and healthy.
During my dormancy, my needs are minimal but specific. Water is my most critical requirement, yet the amount needed is vastly reduced. The goal is to prevent my soil from completely drying out and becoming a dust-like brick, which would desiccate and kill my roots. Water me sparingly, only when the top inch or two of soil is dry to the touch. This might mean watering only once every few weeks. The cooler temperatures and my dormant state mean I use water extremely slowly. Overwatering is a grave danger; soggy, cold soil will quickly lead to root rot, from which I cannot recover. Please withhold all fertilizer during this time; I am not growing and cannot use the nutrients.
As daylight increases and temperatures slowly rise in late winter or early spring, I will begin to show signs of life. You will notice new, small leaves emerging from my stems. This is the signal to gradually increase watering and, once I am producing consistent new growth, apply a diluted, balanced fertilizer. After the danger of frost has passed, you can acclimate me slowly to the outdoors again. This process of "hardening off" is essential to prevent shock. Once acclimated, I can be repotted with fresh potting mix, placed in a sunny spot, and will reward your care with a new season of abundant, colorful blooms.
