Answer: Mandevilla is a sub-tropical plant and won't live if left outdoors in your winter weather. If you have the mandevilla growing as a potted plant, you can certainly keep it from year to year with very little effort. Even in a container you can set it near your arbor and allow it to climb. In the fall, simply cut it back and take it indoors. It will grow and climb (or cascade over a tabletop). Then in the spring you can cut it back and set it outdoors near your arbor again. Here's what you would normally do: In the fall, when nightime temperatures average about 50F, trim it back as needed to either disengage it from the trellis and/or make it fit indoors. Move it gradually to a shadier location so it will get used to lower light levels such as you would have indoors, but do not leave it outside when temperatures drop below about fifty (if this threatens, take it indoors at night and back outdoors to a shady spot during the day). After 3-4 days of exposure to shade, move it indoors to the brightest (hopefully sunniest( spot you have. Keep it out of drafts and keep the humidity around it high if possible. Expect some yellowing of leaves in protest of the move. Reduce watering and fertilizing as the plant's growth slows. In spring, reverse the process to reacclimate it to the outdoors and brighter light levels. You might also repot it in the spring and trim it back a bit in preparation for the coming growth spurt outdoors. Hope this information clarifies things for you!
Q&A Library Searching Tips