What is Allamanda?

Allamanda is a genus of tropical plants native to Central and South America. These plants characteristically grow as vines or shrubs and are very rapid growers in environments they like. They are grown as ornamentals in tropical gardens all over the world and can also be cultivated in greenhouses. Gardeners interested in growing Allamanda should be aware that these plants are poisonous, producing a sticky sap known to be a skin and eye irritant.

Depending on how heavily a plant is pruned and trimmed, Allamanda can grow as a vine, an upright shrub, or a low tree. The leaves are dark green and leathery with a lance-like appearance, and the flowers are bright yellow and very large. This plant is also known as the golden trumpet or yellow bell, referencing the distinctive shape of the flowers. Some cultivars have been bred to produce cream, white, and pinkish flowers.

These plants are hardy in United States Department of Agriculture (USDA) zones nine through 11. They need relatively humid weather and require full sun or very bright light. In extreme heat, it is necessary to water the plants thoroughly to keep them from wilting, and the plants require rich, well-drained soil with a relatively neutral pH balance. In nature, Allamanda plants are often found along the edges of streams and rivers, taking advantage of the increased humidity and the rich deposits of nutritious decaying organic material that tend to accumulate near waterways.

Gardeners in the tropics can cultivate Allamanda as a hedge or standalone garden feature. Plants in this genus can become invasive in some regions, growing rapidly and aggressively and taking over large areas of the garden. It is advisable to keep them well pruned to prevent them from spreading where they are not wanted. Careful pruning can also help shape bushes into a more aesthetically pleasing shape. The plants can bloom year round in many environments although it is advisable to slack off on fertilizer and water in the fall to give Allamanda some time to rest and recover.

Greenhouse gardeners can also cultivate plants in this genus, and some people have success growing Allamanda in sun rooms and other indoor areas. It is important to keep the plants in an area where pets cannot go, because animals can become severely ill if they eat parts of these plants. Gardeners should also wear gloves when pruning and shaping, and if they burn the cuttings, respiratory protection should be worn.

Nurseries sometimes carry seedlings, and gardeners can also grow these plants from cuttings or seed if they have friends and neighbors cultivating Allamanda.