A striking ornamental, mandevilla (Mandevilla splendens, formerly Diplandenia splendens) is a woody vine that you can prune into a shrub-like form. Native to Brazil, mandevilla can climb up to 10 feet, yielding clusters of white or pink funnel-shaped flowers with gold throats. The flowers are about 4 inches wide.The plant is hardy in U.S. Department of Agriculture plant hardiness zones 9 through 11.
Mandevilla displays its showy flowers in the summer but puts forth a small amount of flowers all year long. The flowers are complemented by handsome, dark, leathery leaves that grow up to 8 inches long. Its fuzzy young stems twine around supports. Mandevilla grows rapidly, quickly filling in space. To get a shrub-like form, prune its top, inducing it to grow more foliage and flowers at the bottom.
Mandevilla tolerates salt moderately well, and you can use it to block the spread of dunes. Train it to climb up a lattice for a quick-growing, colorful screen or let it trail from the rail of a porch, patio or deck. Mandevilla looks especially good twining over a mailbox or arbor or growing on a fence. It is a colorful addition to a hanging basket or trailing down a wall.
Either buy potted mandevilla starts from a nursery or plant cuttings in summer. Before you plant a cutting, dust its stem end of with rooting hormone, available at most garden supply centers. This will stop the flow of sap from the cut and stimulate root growth. Mandevilla flowers best in the sun, but midday shade is recommended in very hot locations. It tolerates a wide range of soil from slightly acidic to slightly alkaline and from clay to sand. Space multiple mandevilla plants at least 36 inches apart.
If you live in a climate that’s colder than mandevilla’s outdoor growing range, grow it in a container that stays outdoors in the summer and is brought inside in the winter. Plant it in a mixture of equal parts sand, potting mix and peat moss. Prune it back to a comfortable size before you move it indoors -- up to half its size or less. Mandevilla will grow slowly over the winter, so reduce watering. It does best indoors when night temperatures are 60 to 65 degrees Fahrenheit and daytime temperatures above 70 F. Remove old or crowded stems in late winter or early spring.