Overwintering Mandevilla: How to Protect Mandevilla Flowers

Mandevilla plants, or rocktrumpets, are a genus of dozens of tropical plants and flowering vines in the Apocynaceae family. These plants produce waxy, green leaves and fragrant, trumpet-shaped flowers similar in appearance to those of a hibiscus or dipladenia. Mandevilla flowers bloom in warm climates, akin to its native South America, producing vibrant colors, such as scarlet red or bright yellow. Home growers often plant mandevilla vines outdoors in large pots with a trellis, but some species can also serve as ornamental houseplants in indoor plant containers or hanging baskets.

Follow these gardening tips and winter care techniques to help your mandevilla survive and thrive next year.

1. 1. Prune your mandevilla in early fall. Before temperatures drop below freezing, prune the whole plant back to just a few inches above the soil. This keeps the mandevilla compact so it can more easily recover in spring and produce new growth. As you prune, a milky sap—similar to that of a poinsettia—might appear on the cut end of the vine. This is completely natural and will not harm the plant. If you prefer to keep your mandevilla as a houseplant, keep the vines as long as you find manageable.
2. 2. Move your plant indoors before the first frost. Mandevilla vines can survive consistent nighttime temperatures above 45 degrees Fahrenheit. However, once temperatures shift to lower than 40 degrees Fahrenheit and the first frost is imminent, you should bring your plant indoors for the winter months. Inspect your vines for insects and treat any infected leaves with insecticidal soap or neem oil to avoid bringing pests into your home.
3. 3. Water your mandevilla plant carefully. Indoor mandevilla care might require more frequent or less frequent watering depending on the humidity levels in your home. If your mandevilla is in an area that stays above 60 degrees Fahrenheit, the plant will likely not go dormant over the winter, and you can water it as you normally would whenever the soil around the stems appears on the dry side. If you keep the plant very cool, however, it might enter a natural dormant state to reserve energy and moisture. The vines will experience limited growth and leaf drop until the next growing season in early spring. Begin watering your mandevilla sparingly during dormancy, adding only enough moisture to prevent the soil from becoming bone-dry but to still avoid root rot.

Grow your own garden with Ron Finley, the self-described "Gangster Gardener." Get the MasterClass Annual Membership and learn how to cultivate fresh herbs and vegetables, keep your house plants alive, and use compost to make your community—and the world—a better place.