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Allamanda spp.

golden trumpets

Apocynaceae

Tropical America (Mexico to Argentina, centered in Brazil)

Attracts Pollinators Attracts Butterflies Container Friendly

Native to North America

SunFull Sun

WaterMedium

HardinessZones 10–11

Overview

Allamanda spp. is a genus of about 15 species of evergreen shrubs and scrambling vines in the dogbane family (Apocynaceae), native to tropical America from Mexico to Argentina. Stems are woody, sometimes climbing 6–20 feet (1.8–6 m), with whorled or opposite leathery leaves 3–6 inches (8–15 cm) long and milky sap throughout. Flowers are trumpet-shaped with five overlapping lobes, 2–5 inches (5–13 cm) across, mostly bright yellow, with purple-pink in A. blanchetii. Bloom is nearly continuous in warm conditions. Fruit is a spiny capsule that splits to release winged seeds. A. cathartica is the widely grown golden trumpet, a vigorous scrambler, while A. schottii forms a more compact shrub. All parts contain toxic compounds, and the milky sap irritates skin and acts as a purgative if eaten. Plants are frost-tender, hardy only in USDA zones 10–11, and grown under glass or as container plants elsewhere.

Native Range

Native to tropical and subtropical America, from Mexico and the Caribbean through Central America to Brazil and Argentina, with the greatest diversity in Brazil. Grows along riverbanks, in moist thickets, and at forest margins in warm, humid lowlands from sea level to about 3,000 feet (900 m).

Suggested Uses

Grown on fences, trellises, and pillars and as a free-standing or container shrub in frost-free and Mediterranean climates, spaced 4–8 feet (1.2–2.4 m) apart. In cooler regions plants are grown in greenhouses and conservatories. The toxic sap limits use in gardens shared with pets and small children.

How to Identify

Recognized by large trumpet-shaped flowers with five overlapping lobes, mostly yellow, milky sap in all parts, and whorled leathery leaves. Flowers are 2–5 inches (5–13 cm) across. The spiny seed capsule and the trumpet flowers separate Allamanda spp. from the related Mandevilla spp., which has smaller, smooth pods.

Appearance

Size & Dimensions

Height3' - 20'

Width/Spread3' - 10'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~20 weeks

Spring Summer Fall

Flowering is nearly continuous through the warm season and year-round in frost-free climates, slowing in cool or dry spells. Each flower lasts several days, and plants carry a steady succession of blooms. Warmth, full sun, and regular feeding sustain heavy flowering.

Detailed Descriptions

Flower Description

yellow, sometimes purple-pink

Foliage Description

glossy green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

loam sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

2–3 years

Care & Maintenance

Care Guide

Grows in full sun and moist, fertile, well-drained soil with regular water and feeding through the warm season. Plants are frost-tender and killed below about 32°F (0°C), needing protection or indoor space in cool climates. Climbing species need support and respond to pinching with denser growth. Spider mite, mealybug, and whitefly occur on plants grown under glass. The milky sap irritates skin and is toxic if eaten. Flowering drops sharply in shade or cool weather.

Pruning

Prune in late winter or early spring before new growth to control size, since flowers form on new wood. Cutting back hard renews old, bare plants and increases flowering shoots. Removing seed capsules directs energy into further bloom.