Oleander

Leaves, shoots, and flower clusters

The narrow leaves are lance-shaped or linear-lance-shaped and leathery, with smooth or slightly scalloped edges. A pale midrib is clearly visible, and the leaves grow in opposite pairs or whorls of 3 or 4.

The shoots are branched, and mature plants may have light gray or brown bark. Flower clusters form at the shoot tips; the flowers have five parts and are most often white or pink, less often red or yellowish. Some cultivars have double flowers.

• evergreen, leathery leaves
• a pale midrib on each leaf
• flower clusters at the shoot tips
• fruit consisting of two follicles
• seeds with feathery tufts

Indoors, the plant is usually shaped by pruning: without it, the shoots become elongated and the canopy less dense.

Origin and natural conditions

The species is native to the Mediterranean and southwestern Asia. In the wild, it grows in warm subtropical areas where sunny summers alternate with periods of limited moisture.

Wild plants often grow in riverbeds that dry out. This explains its two-sided care needs: oleander tolerates heat and drier air, but should not be left in excessively dry potting mix throughout the growing season.

In regions with colder winters, the plant is grown in a large container or as a houseplant so it can be brought indoors for winter.

Light and placement

Bright sunlight is needed for active growth and flowering. At a north-facing window, the plant may shed leaves because of insufficient light, so supplemental lighting is often needed there.

Gradually acclimate the plant to direct sun after purchase or winter dormancy. Ventilation is helpful in summer, but avoid cold drafts, especially when the plant is in a cool room.

• a south-facing or very bright window
• gradual acclimation to direct sun
• regular ventilation without cold drafts

If light is insufficient, watering and feeding will not make up for it: growth weakens and flowering becomes unlikely.

Watering, potting mix, and feeding

In spring and summer, water after the top layer of potting mix dries out. In very hot weather, excess water is sometimes left in the saucer, but persistent waterlogging around the roots is undesirable.

In fall and winter, let the potting mix dry out more deeply as growth slows. A well-drained mix reduces the risk of rot: sources give a recipe of sand, leaf mold, peat, well-rotted manure, and a larger proportion of loam.

Apply a mineral fertilizer for flowering plants in spring and summer. It is better to pour the solution onto already moist potting mix rather than dry roots.

Pruning and repotting

Prune after flowering has finished. Pruning does more than control size: shortened shoots branch more readily, helping the shrub stay compact for longer.

Repot young plants annually and mature plants every 2-3 years. For very large specimens, you can replace the top layer of potting mix in spring instead of repotting the whole plant.

• prune after flowering
• repot young plants every year
• repot mature plants every 2-3 years
• replace the top layer of potting mix in large containers
• protect your hands when working with shoots

Remove all prunings immediately, especially if there are animals at home. The sap and leaves are toxic, so do not move from pruning to preparing food or caring for other plants without washing your hands.

Toxicity and safe handling

Oleander is toxic to cats and dogs. All parts of the plant contain cardiac glycosides, including oleandrin; if swallowed, these can cause severe digestive, heart, and nervous system problems.

This is not a plant for a spot where animals or children might chew the leaves. Wash tools after pruning, and do not leave leaves, flowers, or pieces of shoots within reach.

• keep out of animals' reach
• wear gloves when pruning
• wash your hands after contact with sap
• collect fallen leaves separately
• do not use the plant as a home remedy

Medicinal uses of oleander are mentioned in botanical and pharmacological sources, but this does not make the plant safe for self-treatment.

Flowering and propagation

Flowering time depends on the climate and growing conditions. In cultivation, the period is often given as June to October, while botanical descriptions of the species also give a shorter period, from June to August.

The main propagation methods are seeds and cuttings; layering is also used in summer. For indoor growing, cuttings are more common because they preserve the cultivar's traits.

• seeds in spring
• cuttings in spring
• layering in summer

Light, a seasonal drop in temperature, and pruning after flowering are important for bud formation. If the plant is kept in shade or too warm over winter, it may produce leaves without flower clusters.