Although this plant is often referred to as the golden trumpet “vine”— it is after all a climber—its habit when grown in a pot is to sprawl or lean. Its demand for warmth, a humid atmosphere, and plenty of sun means that it is a plant for the sunroom or greenhouse, although it can be used as a short-term houseplant in other rooms.
If grown in large containers, climbing allamandas can be trained on a trellis or wire support to cover a wall; and they are very attractive when encouraged to grow up into the ceiling space.
Allamandas are spectacular in flower, and if it were not for their rather weak constitution, they would undoubtedly be seen more often. The glossy, dark green, oval leaves are 4-6in/10-15cm long and are borne on long stems.
The flaring, buttercup yellow trumpet blooms of Allamanda cathartica appear throughout summer and fall, and can be as much as 4in/10cm wide.
Leaves yellow and drop naturally. Prune any naked stems by half to encourage new leaf buds to break.
In damp conditions, collar rot fungus can attack the soft, fleshy stem. Scatter horticultural grit on the soil around the stem to help prevent it.
Honeydew, the sticky dark secretion from aphids, can be unsightly.If seen, wash the leaves with slightly soapy water.
ORIGIN Guyana; Brazil.
HEIGHT To 8ft/2.4m and more with a similar spread.
POTTING MIX Soil-based.
REPOTTING Move into a pot one size larger each spring.
PROPAGATION Take 3-4-in/8-10-cm tip cuttings in early spring.
KEEPING PLANTS To keep the plant healthy, cut it back to roughly half its size just before growth resumes after the winter rest.
Allamanda cathartica Apocynaceae PLANT CARE
- Bright light, with 3-4 hours of direct sunlight.
- Minimum of 60°F/16°C in winter.
- Water moderately in the growing season, sparingly in winter.
- Stand the plant on a tray of wet pebbles and mist it daily during summer.
- Apply a weak liquid fertilizer every 2 weeks from early spring to late summer.
- In smaller rooms, train this plant over a wire framework; although the stems are tough, they are flexible and easy to wind and unwind.