The Mandevilla (also called the rocktrumpet) is a genus of lush, tropical vines identified by showy, trumpet-shaped flowers that bloom continuously from spring until the first frost. Native to Central and South America, it thrives in warmth and humidity. Its vigorous, twining growth habit and vibrant pink, red, or white blossoms make it a popular choice for gardeners seeking a dramatic flowering container plant. Successfully growing this tender perennial requires understanding its specific environmental needs.
Creating the Perfect Habitat
The Mandevilla thrives with ample light but must be protected from the harshest sun. It requires at least six hours of bright light for optimal blooming, but intense afternoon sunlight can easily scorch its foliage. A spot providing morning sun followed by bright, indirect light or filtered shade in the afternoon is the best choice for plant health and flower production.
Proper drainage is essential for a healthy Mandevilla, as its roots are highly susceptible to rot. The ideal potting medium is a sandy, well-draining mix, rich in organic matter, maintaining a slightly acidic to neutral pH (6.0 and 7.8). Always use a container with functional drainage holes to allow excess water to escape freely.
As a tropical plant, the Mandevilla is highly sensitive to cold. Growth slows significantly below 60°F, and it cannot tolerate temperatures consistently below 50°F (10°C) without cold damage. When daytime temperatures are reliably above 50°F, the plant can safely be moved outside to begin its active growing season.
Daily and Weekly Maintenance
A consistent watering regimen supports the Mandevilla’s rapid growth and heavy flowering, but overwatering must be avoided. Water the plant thoroughly until it drains from the bottom of the container, then allow the soil to dry slightly. Wait until the top one to two inches of soil feel dry to the touch before watering again.
During the active growing season (spring and summer), the Mandevilla benefits from regular fertilizer to fuel continuous flowering. It responds best to a liquid, water-soluble fertilizer high in phosphorus, which boosts bloom production. Apply this formula every two weeks, following dilution instructions to avoid root burn.
Since the Mandevilla is a twining vine, providing a vertical support structure (like a trellis, cage, or arbor) is essential for climbing varieties. This support encourages upward growth and showcases the flowers. While removing spent flowers (deadheading) keeps the plant tidy, it is not necessary to promote more blooms.
Pruning maintains shape, manages size, and encourages a bushier habit, as flowers form on new growth. Light trimming of unruly vines can be done anytime during the summer. Hard pruning to shape the plant should be saved for late winter or early spring before the new season’s growth begins. To encourage a denser appearance, pinch back the tips of young, non-flowering stems by about a half-inch.
Protecting Your Plant from Seasonal Threats
For gardeners in cold climates, the most important task is preparing the Mandevilla for overwintering indoors. Bring the plant inside before the first frost, or when nighttime temperatures consistently drop below 50°F. Prior to moving it indoors, prune the vines back to a manageable size, often by as much as one-third of the plant’s mass.
The Mandevilla can be overwintered in two ways: kept as an active houseplant near a bright window, or forced into a semi-dormant state. For dormancy, store the plant in a cool, dark location, such as a basement or garage, where temperatures remain above 45°F. Water must be drastically reduced during this period, providing only enough moisture to prevent the soil from becoming bone-dry.
Moving the plant indoors for the winter can stress it, making it susceptible to pests. Common pests include spider mites (leaving fine webbing and tiny yellow dots) and mealybugs (appearing as small, cottony masses on stems and leaf joints). Inspect the plant thoroughly before bringing it inside to prevent an infestation from spreading to other houseplants.
Small infestations can be controlled by applying a strong spray of water to dislodge the pests. Persistent problems require more targeted intervention. Both insecticidal soap and horticultural neem oil are effective treatment methods for controlling these common pests, applied according to package directions. These treatments work by suffocating the insects and should be repeated weekly until the threat is eliminated.