Mandevilla are woody perennial vines. Native to tropical parts of South America, they are desirable for their masses of showy, trumpet-shaped flowers that can grow as large as 4 inches across. The plant itself can grow to heights of 10 feet. There are over 100 species of mandevilla, according to Clemson University, and all of them will reward the home gardener with a nonstop show of blossoms if given proper care.
Mandevillas prefer climates with mild daytime and evening temperatures. The lowest temperatures these plants can tolerate are in the high 40s Fahrenheit. For that reason, they are often grown in containers where they can be brought indoors when cold weather threatens. They are also sometimes grown as houseplants. Mandevillas planted outdoors should only be grown in United States Department of Agriculture (USDA) hardiness zones 9 through 11.
Soil and Water
Plant indoor mandevillas in a potting soil that has a large amount of peat moss and coarse sand or perlite added, to aid in drainage. These flowers need well-draining soil. Overly soggy soil or standing water will cause the roots to develop a fungal infection called root rot. Outdoor mandevillas prefer well-drained soil rich in organic material. Add sand and humus to improve drainage and nutrients if needed. Support the vine as well with a trellis or stake. Water when the top few inches of soil dries out. The mandevilla vine can tolerate brief periods of drought.
Although mandevilla prefer warm temperatures, they do not like bright, direct sunlight, which can scorch the sparse foliage of the vine. Still, these plants do need some sun for optimum flowering. Home gardeners should plant outdoor mandevilla in a location where they will be protected by dappled shade, or where they will be exposed to the gentler morning sun followed by afternoon shade. Indoor mandevilla can be placed near a window, where they will receive bright but indirect light, or light that is filtered through an opaque curtain.
Mandevilla are heavy feeders. Feed the vine every two weeks during the growing season (spring through early fall) with a water-soluble, high-phosphorus fertilizer (10-20-10).
Insects can bother this plant, including whiteflies, scale, mealybugs and spider mites. Examine new plants carefully for signs of these insect pests, including under the leaves, before purchasing them. Signs may include tiny black or white specks, or leaves that are ragged or curled on the edges. If you notice insects on your mandevilla, try spraying them off with a powerful stream of water, or use an insecticidal soap. Follow the directions on the soap's label for best results.