Cultivation notes

To keep mandevilla healthy, here are a few tips on cultivation;

• As large woody climbers, mandevilla are at their best when planted in a conservatory or greenhouse border. As houseplants therefore, they can be difficult
• In pots, although any good general purpose potting medium is satisfactory, members report best results from using a loam-based John Innes No 3 compost with added grit to create an open, well-drained compost
• Place in full light, but with shade from hot, scorching sunshine
• Re-pot in February or early March
• The plant naturally flowers in the latter part of summer on the current year's growth and, therefore needs early warmth to ensure good vigorous shoots are produced
• Warm, humid conditions are required in spring, with daytime temperatures of 21ºC (70ºF) and night-time temperatures of 18ºC (65ºF)
• Overwinter at a temperature preferably not below 15ºC (60ºF) at night. In cold conditions it is likely to lose most of its leaves. One species – Mandevilla laxa – is hardy down to around 5°C
• In the growing season, water moderately and apply a balanced liquid fertiliser monthly. Water sparingly from October to February, then moderately until April when growth becomes vigorous. Mist daily in summer

Pruning and training

Mandevilla can make large plants so pruning largely helps keep them in check;

• After planting, create a framework of stems by selecting three-to-five strong, young shoots
• If there is only the one main shoot, reduce its length by one-third to encourage further growth from the base
• In late winter or early spring, once established, plants can be trimmed to keep them restricted to the available space
• Prune out any overcrowded or weak shoots
• Spur prune in late winter or early spring by taking side shoots back to within three or four buds of their permanent framework. This will encourage the creation of flowering wood

Propagation

Sow seed in temperatures of 18-23°C (64-73°F) in spring.

Softwood cuttings in early summer should be successful if placed in a propagator with bottom heat of 20-25°C (68-77°F).

Cultivar Selection

Mandevilla × amoena ‘Alice du Pont’ AGM (Syn: Mandevilla × amabilis): is a popular conservatory climber with large numbers of pink flowers in late summer. It reaches a height of up to 7m (22ft) and can tolerate temperatures of 10-15°C (50-59°F).

M. laxa AGM (M. suaveolens, M. tweediana; Chilean jasmine): The selling point of this mandevilla is its strongly scented flowers of white or creamy-white. It can reach a height of 3-5m (10-15ft). It can survive short periods of temperatures down to 5°C (41°F).

M. boliviensis AGM: At 3-4m (10-13ft), this is the least vigorous of those mentioned here and has white flowers with yellow eyes. Another one for the heated conservatory with minimum temperatures of 10-15°C (50-59°F).

Links

RHS Plant Selector

Problems

Mandevilla can suffer from the usual houseplant pests such as mealybugs.