I've been over-wintering Mandevilla vines for about 3 years with some success. Every year seems to be a little better. Even though I have lots of windows in my house, I don't have enough light for Mandevilla vines because I live in Michigan with cold dark winters and my windows are mostly Northern exposure. My Mandevilla vines live in the basement where there are no windows...only grow lights. I use an Orchidarium. This provides humidity, air flow and substantial light. The plant blooms all winter, and then goes sort of dormant and is re-awakened in May/June when it's replanted outdoors. My Mandevilla vine lives in a pot on a shepherd's hook outside...so there probably aren't many bugs to begin with. I do wash the leaves and rinse the soil and repot it before bringing it in. I put a Krogers bag loosely around the pot. This makes it easy to spot soil type bugs. I use a wet-vac to vaccuum any dropped leaves ASAP. As the plant begins to drop more leaves, I begin light fertilizing. Hope this helps.

Wow! what an amazing thread for such a beautiful plant, from my experience and what ive seen is that these do fine-- given light-- not cut back at all maybe for height and space convenience near a bright window, preferably south, and it will bloom still, not as much but still something to make you smile in december and january. Then once your area starts to get warm and nights are above 55-65, watch this thing take off! and pinch back for blooms if you like

marshgirl, Mandevilla are easy to overwinter. There are two methods. Both work. In both cases place plant in a good sized pot with good draining soil. Then.... 1. Cut the vine back to within 12' inches of the soil line. Place pot in a bright, sunny window and be patient. Or.... 2. Before potting cut back the vine so that it is about 4' to 6' long. Now work along the length of the vine cutting off every side branch to within 4" of the stem. This is called 'saddle pruning'. Now, pot the vine and jam some sort of support for the vine in the pot. I loop a long, fresh cut piece of bamboo in an arch form which works well. Again place in a sunny window. Don't be surprised if your vine is grumpy over the winter and looks dead. As spring approaches it will spring to life. When you return it to the outdoors remember to give it a hardening off period to adjust.

I have overwintered my mandevilla vine in my above ground basement window for the last three years. I sit the pot on the window ledge where it gets sun from the southern exposure. The basement is not heated so it stays cool but the plant survives just fine. I cut the vine back to about 2 feet long, it does lose some leaves over the winter but it rebounds as soon as I put it back outside in the spring. It has even bloomed while in the basement. Linda