Golden Trumpet

Allamanda cathartica is native to Brazil, where it grows in the Atlantic Forest region and other tropical lowland habitats. It has been cultivated for so long across the tropics that its exact native range within Brazil is somewhat uncertain.

• Named in honor of Dr. Frederik Allamand, an 18th-century Swiss-Dutch botanist who sent specimens to Linnaeus from Suriname
• The species name cathartica means "purging" or "cleansing," referring to its traditional (and dangerous) use as a purgative medicine
• Has been cultivated in tropical gardens worldwide for over 200 years
• One of the most commonly planted ornamental vines in tropical Asia, the Caribbean, and Central America
• The genus Allamanda contains approximately 15 species of tropical American shrubs and vines
• In its native Brazil, the plant is called "alamanda" or "chapéu-de-napoleão" (Napoleon's hat)
• All Allamanda species are toxic — the plant has been used as a fish poison in some traditional cultures
• Widely available in the horticultural trade, with several cultivars selected for flower size and color intensity
• Has naturalized in many tropical regions but is not generally considered a serious invasive species

Golden Trumpet is a vigorous evergreen vine or scrambling shrub climbing by twining stems to heights of 3–6 m, or forming a rounded shrub 1.5–2.5 m tall and wide.

Stems: Green, smooth, somewhat succulent, producing copious milky white latex sap when cut or broken. Young stems are green; mature stems become woody at the base.

Leaves: Whorled in groups of 3–5 (typically 4), elliptic to obovate, 7–15 cm long and 3–6 cm wide, leathery, dark glossy green, with smooth margins and a prominent midrib. Leaves are arranged in distinctive whorls rather than the pairs typical of most plants.

Flowers: Spectacular — large, broadly trumpet-shaped (salverform), 8–12 cm across, with 5 broad, overlapping, brilliant golden-yellow petals that flare from a narrow tube. The throat is often marked with deeper orange-red lines that serve as nectar guides. Flowers are produced in terminal cymes of 2–6 blooms, continuously through the warm season. Each flower lasts 2–3 days, but production is continuous.

Fruit: Large, spiny, rounded capsules 3–5 cm in diameter, covered in soft prickles, containing numerous winged seeds. Rarely produced in cultivation.

TOXIC: All parts contain a toxic milky latex sap and poisonous alkaloids (including allamandin, plumericin, and ursolic acid). The sap causes contact dermatitis and eye irritation. Ingestion causes vomiting, diarrhea, and potentially cardiac effects. Handle with gloves.

Golden Trumpet grows naturally in the warm, humid lowland tropical forests of Brazil, where it scrambles through the understory and along forest edges.

• Requires warm tropical or subtropical conditions — thrives in temperatures of 20–35°C
• Best in full sun for maximum flowering — tolerates partial shade but blooms less
• Prefers moist, fertile, well-drained soils rich in organic matter
• Sensitive to cold — damaged below 10°C and killed by frost
• The whorled leaf arrangement is distinctive and makes identification easy
• Flowers are pollinated by hummingbirds and large bees in the wild
• The brilliant yellow color is visible from great distances, making the plant a dramatic landscape specimen
• In the tropics, it can be maintained as a free-standing shrub or trained as a vine on pergolas and fences
• Not typically invasive, though it has naturalized in some tropical regions
• The toxic sap deters most herbivores from browsing

Golden Trumpet is a bold tropical vine that requires warm conditions and careful handling due to its toxic sap.

Light: Full sun — at least 6–8 hours of direct sun for best flowering. Will tolerate light afternoon shade in the hottest climates.

Soil: Fertile, moist, well-drained soil. Enrich with organic matter. pH 5.5–6.5. Slightly acidic conditions preferred.

Planting: Plant container-grown plants in spring in warm climates. Provide a trellis, pergola, or fence for climbing, or plant as a freestanding shrub. Space 1–2 m apart.

Container Growing: In cold climates, grow in large containers and bring indoors before temperatures fall below 10°C. Use a well-draining potting mix.

Watering: Regular, deep watering during the growing season. Do not allow to dry out completely. Reduce water in winter.

Fertilization: Feed monthly during the growing season with a balanced or bloom-boosting fertilizer.

Pruning: Prune in late winter or early spring to control size and shape. Can be cut back hard — it regrows rapidly. Remove dead or damaged wood.

Caution: Wear gloves when pruning or handling — the milky sap can cause skin irritation and eye inflammation. Wash hands thoroughly after contact. Keep away from children and pets.

Hardiness: USDA Zones 10–11. Grow as an annual or container plant in cold zones.

Propagation: By semi-hardwood cuttings in summer. Root in moist potting mix with bottom heat.