Mandevilla is a tropical, vining plant prized for its glossy foliage and showy, trumpet-shaped flowers that bloom in vibrant shades of pink, red, or white. Native to Central and South America, this plant brings a lush, exotic look to gardens and patios throughout the summer season. The classification of the Mandevilla as a perennial or an annual depends entirely on the climate where it is grown.
The Hardiness Question: Perennial or Annual?
The Mandevilla is botanically a perennial, meaning its natural life cycle is to live for more than two years. However, its survival is deeply tied to temperature, as it is a tropical plant that cannot tolerate freezing conditions. Only gardeners residing in United States Department of Agriculture (USDA) Hardiness Zones 9, 10, and 11 can consistently grow the Mandevilla outdoors year-round as a true perennial.
In these warm, frost-free zones, the vine continues to grow and rebloom season after season. Outside of these specified zones, the plant behaves strictly as a tender annual because colder winter temperatures will cause it to die back after the first hard frost. For the majority of the country, Mandevilla must be replanted each spring or actively protected through the winter to survive. The plant cannot withstand temperatures below approximately 45 to 50 degrees Fahrenheit.
Bringing Mandevilla Indoors for Winter
Successfully keeping a Mandevilla alive in cooler climates requires moving it indoors before the first frost, ideally when nighttime temperatures consistently drop below 50 degrees Fahrenheit. Preparation begins with pruning back the plant’s long canes and foliage to a manageable size, often to just a few inches above the soil line if planning for a dormant winter. Heavy pruning is well-tolerated and helps the plant conserve energy during its indoor rest period.
Before relocating the plant inside, a thorough inspection for pests is necessary to prevent introducing insects like spider mites or whiteflies into the home. Any signs of infestation should be treated with insecticidal soap or neem oil before the move. Once inside, the plant should be placed in a cool, dark location, such as a basement or unheated garage, where temperatures remain above 45 degrees Fahrenheit to encourage a natural dormant state.
During this period of dormancy, the plant’s growth slows significantly, and it may experience some leaf drop. Watering must be drastically reduced, only providing enough moisture to keep the soil from becoming completely dry and preventing root rot. Fertilization should be entirely suspended until early spring, signaling the end of the resting period.
Essential Care for Vigorous Summer Growth
Once the threat of frost has passed and temperatures are consistently above 55 degrees Fahrenheit, the Mandevilla can be returned outdoors to begin its active summer growth cycle. For the most abundant production of its trumpet blooms, the vine requires a location that receives a minimum of six hours of direct sunlight daily. While it tolerates some partial shade, too little light will result in significantly fewer flowers.
The plant thrives in a well-draining potting mix that is rich in organic matter, which prevents the roots from becoming waterlogged. During the summer, Mandevilla requires consistent watering, keeping the soil evenly moist, but allowing the top inch or two of soil to dry out between waterings. Frequent watering is particularly important for container-grown plants due to faster moisture evaporation.
To support continuous blooming throughout the season, the Mandevilla benefits from regular feeding with a balanced, water-soluble fertilizer. Applying a general-purpose fertilizer every two to three weeks during the growing season provides the necessary nutrients for flower development and new vine growth. Providing a trellis or other support structure is also necessary, as the vines naturally climb and twine as they grow.