How can I overwinter a mandevilla in my south facing sunroom in Niagara-on-the Lake. We keep the room around 8 degrees Celsius.
Mandevilla is a woody vine that should be brought in before temperatures drop below 15C. Your sunroom is too cold to over-winter a mandevilla vine. Generally it needs a sunny room where a temperature of at least 12.5 C to 15 C. is maintained. If you don’t have another sunny room which is kept at a warmer temperature you can let the plant go dormant. This involves placing it in a dark area which is kept at 10 – 15 C. To prepare the plant, cut it back to about 30cm above the soil line. Wash the remaining leaves with a damp rag or wet paper towel to remove any pests. Treat for insects if needed. To ensure the plant doesn’t wilt, water it about once per month or when the top 2.5cm of soil begins to dry. It will eventually lose some of its leaves. Early spring growth indicates the plant is breaking dormancy. The mandevilla vine can be moved to the sunniest room in your home where the temperature is at least 15 C. Resume normal watering and fertilization. Move it back outdoors when temperatures are consistently above 15C. At this point the plant can be repotted in a larger pot with fresh potting mix.
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