Oleander

Oleanders are ideal for large containers or planted into a sunny border in frost-free greenhouses or conservatory. They can occasionally be grown outdoors all year round in the extreme south west of England and in sheltered city gardens particularly in central London.

• Position in bright sunlight with good air circulation
• Pot up using a soil-based compost such as John Innes No 3, with added grit (up to 30 percent by volume) for good drainage
• Water freely in summer and apply a balanced liquid fertiliser every two weeks until June. Then switch to high potassium fertiliser, using it until the flower buds show colour
• In winter, stop feeding, reduce the watering, (keep plants on the dry side), and maintain a minimum night temperature 2-10ºC (35-50ºF)
• Re-pot if necessary, after pruning in late winter or early spring. Maintain plant at 16-18ºC (60-65ºF) and 10-13ºC (50-55ºF) at night and water sparingly until plant is growing strongly, then resume usual watering and feeding
• Where re-potting is impractical, top-dress by removing the top 2.5-5cm (1-2in) layer from the surface of the root-ball and replace with fresh compost

Toxicity

All parts of this plant are poisonous if eaten and contact with the foliage may irritate the skin.

Pruning and training

Flowering occurs in late summer (July to October) on new shoots of the current season’s growth, so prune in late winter or early spring. Gloves should be worn when pruning as the sap is potentially harmful.

• Remove all thin crowded shoots and tip-prune young plants
• Cut flowered shoots by half and the side shoots to 10cm (4in)
• If over-wintering large plants is difficult, reduce the plant’s size in late autumn
• Plants can be left un-pruned to grow into large bushes where space allows in conservatory beds or where plants are regularly re-potted
• Plants restricted in containers will flower less and become less vigorous over time and will need to be replaced

Propagation

Oleanders can be propagated in several ways:

• Take semi-ripe cuttings from July to September using 7.5cm (3in) sections or terminal shoots of the current year’s growth
• Place in propagator with bottom heat 12-20ºC (54-68ºF) to speed rooting, using half well-drained potting compost mixed half sharp sand or perlite
• Cuttings can also be rooted in water or by layering
• Collect seeds in autumn and sow in spring at 16ºC (60ºF) and should germinate in two weeks

Nerium oleander ‘Variegatum’ AGM: Attractive leaves with white to pale yellow margins and double pink flowers. Height 1-3m (3-9ft) and spread 1-2m (3-6ft).

Nerium oleander ‘Album’: Single white flowers and grey-green foliage, approximate height 2-6m (6-20ft) and spread 1-3m (3-10ft).

Nerium oleander ‘Splendens’: Double pink flowers and grey-green foliage, approximate height 2-6m (6-20ft) spread 1-3m (3-10ft).

Links

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AGM plants

Generally easy to grow but may suffer the following problems.

• Delayed flowering may occur in cool, dull conditions
• A fungal leaf spot was reported on oleander in 2012, but it is unclear if this will become a serious problem in Britain
• May suffer from common conservatory pests such as oleander scale, scale, red spider mite and mealybug

Bananas
Brugmansia (angel's trumpet)
Bougainvillea
Citrus
Cool conservatory and greenhouse plants
Oleander scale
Overwintering tender plants
Strelitzia
Tree ferns