Allamanda blanchetii: Purple Allamanda

This document is part of a series originally authored by Edward F. Gilman.

Introduction

Purple allamanda (Figure 1) is an evergreen vine or climbing shrub with 3-inch-long, funnel-shaped blooms (Figure 2), which are reddish-purple fading to pink, giving a two-toned effect. The light green, pubescent leaves are arranged in whorls on weak, sprawling stems (Figure 3). Seed pods are spiky capsules, which turn brown once mature (Figure 4). While it can be allowed to rapidly cover an arbor or other support structure, with careful pruning, purple allamanda can also make an attractive free-standing shrub. It is often used to cover the base of a mailbox or pole. Allamanda has a cascading effect when planted near the edge of a wall, or is suitable for a large hanging basket. This plant is also well suited as a groundcover, or for a container/above ground planter. Rapid growth creates a sprawling form with individual shoots growing alone, away from the rest of the plant. Regular pinching of the new growth will keep the plant fuller and within bounds but should be done when buds are not visible on the plants to maximize the blooms. Over-pruning this plant will decrease flowering, as the plant generally blooms on new growth.

General Information

Scientific name: Allamanda blanchetii

Previous name(s): Allamanda violacea

Pronunciation: al-luh-MAN-duh blan-chet-E-eye

Common name(s): purple allamanda

Family: Apocynaceae

Plant type: vine; shrub; groundcover

USDA hardiness zones: 9B through 11B (Figures 5 and 6)

Planting month for zone 9: year-round

Planting month for zones 10 and 11: year-round

Origin: not native to North America

Invasive potential: not known to be invasive

Uses: container or above-ground planter; ground cover; cascading down a wall; large hanging basket; veils a trellis

Availability: generally available in many areas within its hardiness range

Description

Height: depends upon supporting structure

Spread: depends upon supporting structure

Plant habit: spreading

Plant density: moderate

Growth rate: moderate

Texture: coarse

Use and Management

Purple allamanda produces best growth and blooms when planted in full-sun locations. This plant should be planted in frost-free sheltered locations in nematode-free soil; however, it may be planted in a variety of soil types. Water plants generously until well-established. Pruning may be needed to keep this plant in a desired shape or within bounds of the planting area. Purple allamanda is a highly adaptable plant to use in the landscape in a variety of ways. Its evergreen leaves and year-round flowers bring added interest and lend a tropical feel to the landscape. It may be used to veil a trellis, cascade down a wall, espalier; or grown in a container or large hanging basket. With maintenance, this plant also makes a suitable specimen plant or shrub. Use caution around children and pets as all parts of this plant are toxic.

Propagation is by cuttings.

Design Considerations

The purple allamanda works well as a background or massing plant when grown on a trellis or fence to block undesirable views or fill gaps along walls. It can also be used to add interest to an arbor or pole. The medium-size, light green foliage of the allamanda shows well with contrasting plant features such as large leaves, coarse texture, thick stems, and dark green or burgundy color. The loose, sprawling form of the vine contrasts with neat plants such as the clumping, arching forms of grasses and other vase-shaped, small-leaved shrubs. Low-growing groundcover with a mounding or matting form will emphasize the upright form of a trained allamanda on a trellis or arbor. To create a large plant mass along a fence, select other vines with a variety of flower colors, such as white, pink, or yellow to mix with the allamanda for more interest.

Pests and Diseases

Minor (occasional) pest issues include scale, mites, and nematodes. No diseases of major concern.