Will Mandevillas Come Back Every Year?

Temperature Requirements

• Mandevillas require temperatures above 45 degrees Fahrenheit. A brief, light frost kills back the top of the plant, although the roots may survive if soil temperatures don't drop below 45 F. In frost-free climates you can overwinter mandevillas in the garden bed and they will dependably remain evergreen year-round. In USDA zone 8, where occasional light frosts occur, the plant may die back, but the vines usually regrow from the surviving roots the following spring. In colder regions with more prolonged frost, the mandevilla won't come back unless you take steps to overwinter it.

Overwintering Outdoors

• In warm climates, mandevillas require only light watering throughout winter so the soil doesn't dry out completely. In marginal hardiness areas that may experience light frosts, mulch around the plants with a two- to three-inch layer of mulch in fall. The mulch insulates the soil and protects the roots from any short cold snaps. If the vine dies back, cut it off near ground level in the spring as new growth begins to emerge. Growing mandevilla in a partially shaded and protected location, such as near a south-facing wall, further helps protect the roots from light frost so it will come back in the spring.

Overwintering Indoors

• Growing mandevilla in a pot outdoors and bringing it inside for winter provides the best method for ensuring your mandevilla comes back each year in a cold climate. Spray the plant forcefully with water and remove dead or diseased leaves and any pests before bringing it indoors. Provide the mandevilla with all-day sun by setting it near the sunniest window in your house. The vine won't flower in winter due to the reduced light, but it may remain alive and green. In lower light, the leaves may still brown and fall off, but if you water enough so the soil doesn't dry completely, new shoots will emerge in spring. Trim back the dead portions of the vine and move the plant back outdoors after frost danger has passed in spring.

Dormant Plants

• Forced dormancy provides another method for overwintering a mandevilla indoors, and works well if you don't have a suitably sunny area to keep the potted plant. Bring the potted plant indoors once temperatures begin to dip below 60 F. Cut back the vines to an eight- to 10-inch height and rinse the remaining foliage to remove any pests. Storing the vine in a dark 55 to 60 F location allows the vine to go semidormant, but water often enough so the soil doesn't dry completely. Move the plant to a sunnier location in spring so new shoots can begin to grow, while gradually increasing watering to summer levels.