🌺 Mandevilla

What it looks like

How to grow

Mandevilla, also called rocktrumpet, is a tender twining vine with large trumpet flowers in pink, red, or white, often with a yellow throat. Plant outdoors in mid- to late spring, once nights are reliably warm and frost is past, in a large pot with drainage holes or in sandy, well-drained, fertile soil. Give it a trellis, obelisk, or fence from day one, since it grows fast and twines eagerly. In zones cooler than 10, treat it as a patio annual, or bring the pot indoors before first frost to a bright, cool spot and water sparingly until spring. Some compact forms are sold as Dipladenia; they are closely related, bushier, and need less support.

Water & feeding

Keep soil consistently moist but never waterlogged — mandevilla hates wet feet and rots quickly in a pot without drainage. Water when the top inch of soil dries, and feed every 4-6 weeks in the growing season with a balanced fertilizer. Avoid overwatering in winter indoors, when growth slows. Mulch in-ground plants to hold moisture, and mist or group pots in dry air to keep foliage happy.

Common problems

• Root rot from overwatering — use fast-draining mix, pots with holes, and let soil dry slightly between waterings.
• Yellow leaves — often overwatering, cold nights, or a pot-bound plant; check drainage, warmth, and root room before feeding.
• Spider mites, aphids, and mealybugs, especially indoors — wash foliage, isolate affected plants, and improve air flow.
• Milky sap irritates skin — wear gloves when pruning, and keep prunings away from pets and children; the sap is not food.

Harvest & notes

The flowers are the harvest, and they are generous: pick a few trumpets for a vase, where they last several days, and deadhead spent blooms to encourage more. At season’s end in cool zones, cut the vine back by about a third before bringing it indoors, and save cuttings in late spring or summer — softwood cuttings root readily in warm, moist mix, giving you next year’s patio plants for free.

Saving seeds

Mandevilla seed comes in long slender pods that split open to release plumed seed, and the harvest is a matter of catching the pods before they do their job. After flowering, watch for the paired pods. When they start to dry and split, cut them into a paper bag before the fluff carries the seed away. A pod checked a day too late is a pod that has already sown itself to the wind.

There is no stratification, no scarification, no fuss. Sow the seed fresh, the same season you collect it, barely covered, in warm moist mix. Germination is quick in warm soil and poor in cool soil, which is the plant telling you when it wants to grow. Prick the seedlings out once they have a few true leaves and grow them on in pots before planting out.

Named cultivars do not come true from seed, full stop. Most garden mandevillas are hybrids, and their seedlings will be a mix of colors and habits. If you want a particular flower — the exact pink or red or white that made you buy the plant — cuttings are the sure route. Semi-hardwood cuttings taken in warm weather root readily, and a cutting is a clone of its parent. Seed is the route to species plants and to the experiment.

Self-seeding happens in warm climates, where a vine left to ripen will sow itself into pots and bare ground. In most of Florida, mandevilla is a container plant or a warm-season annual, and the seed you save is next year’s patio vine. Stored dry, the seed keeps for a year or two, and Florida humidity is the enemy of stored seed, so dry it thoroughly before jarring it, add a silica gel packet, and keep the jar cool and dark.

Varieties

Every named variety of Mandevilla with its own growing guide:

• Alice du Pont Mandevilla — The classic pink mandevilla: large rose-pink trumpets with hot pink throats, the vine that started it all.
• Sun Parasol Crimson Mandevilla — The compact crimson: huge deep-red trumpets on a tidy, heavily blooming vine, the container mandevilla.
• Sun Parasol Pretty Pink Mandevilla — The clear-pink container mandevilla: delicate pink trumpets that never fade in hot sun, on a compact, heavily branching vine — the mandevilla for pots and trellises.
• Sun Parasol Giant Pink Mandevilla — The big pink mandevilla: oversized bright-pink trumpets on a vigorous, heat-loving vine — the mandevilla for arbors, walls, and big pots.
• Sun Parasol Giant White Mandevilla — The white giant mandevilla: huge, pure-white trumpets with gold throats on a vigorous vine — the mandevilla for moonlight patios and dark foliage.
• Rio Pink Mandevilla — The bushy pink mandevilla: soft-pink trumpets on a compact, mounding vine that needs no tall trellis — the mandevilla for baskets, borders, and small pots.