Oleander

Oleander: how do you recognise it?

Habit

Upright, multi-stemmed shrub; in a tub usually 1.5–2 m tall and 1–1.5 m wide.

Leaves

Narrowly lance-shaped, 10–20 cm, leathery, dark green to grey-green, usually in whorls of three.

Flower

Funnel-shaped, 3–5 cm across, single or double, in clusters at the shoot tips, from June to September.

Colour

Pink, red, white, salmon, apricot or pale yellow.

Fruit

Long, narrow pods that split open and release seeds with a tuft of hairs.

Flowering: June–September · Plants: May · Pruning: March and October

Why grow it?

• Four months of flowers, from June to September, in many colours.
• Evergreen: a full, sturdy container plant even when not in flower.
• Copes with heat, strong sun and dry air on a sunny patio.
• Instantly brings a southern feel to a patio or balcony.
• Easy to root from cuttings, even in a glass of water.

Oleander: where does it grow best?

• Full sun and warmth: the more sun, the more flowers.
• Firm, rich potting compost with some clay or loam; lime is no problem.
• Needs plenty of water in summer; very little in winter.
• Sheltered from strong winds and, for double cultivars, preferably under cover from prolonged rain.
• Use a heavy, stable pot with a drainage hole so it does not blow over.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Dry or normal

Size

2 m tall, 1.5 m wide

Hardiness

Half hardy (to -5 °C): protect it in harsh winters

Goes well with

• Olive: Grey leaves and a Mediterranean feel; also overwintered frost-free.
• African lily: Blue globes of flowers next to the pink or white oleander flowers.
• Myrtle: Evergreen, with fragrant white flowers in the same summer months.
• Lavender: Purple spikes and silvery leaves for a sunny group of pots.
• Lemon tree: Another classic container plant that overwinters the same way, bright and cool.

Oleander: when and how to plant it?

Plant in May.

1. Pot up or repot in May and only put it outside after mid-May, once night frosts are over.
2. Choose a sturdy pot one size larger than the last, with a drainage hole and a layer of grit at the bottom.
3. Mix potting compost with one third garden loam or clay granules for a firm, moisture-retentive mix.
4. Set the plant at the same depth as before and firm the compost well.
5. Water thoroughly straight away.
6. Wear gloves when repotting, as the sap is poisonous.

Care

Watering

Generously in summer, every day in hot weather; during that period a little water may stay in the saucer. In winter only when the compost is almost dry.

Feeding

From April to the end of August, liquid feed for flowering container plants every week. Then stop.

Repotting

Young plants every 1–2 years in spring. For large, older plants, replace the top layer of compost.

Deadheading

Do not cut spent clusters back too far: new buds often appear in the same place.

Moving out

After winter, let it acclimatise in partial shade for a few days, or the leaves will scorch in strong sun.

Tip: In summer, give oleander really plenty of water and a weekly feed: in the wild it grows along streams and needs a lot at that time. That way it flowers from June into September.

Oleander: when to prune it?

Pruning months: March and October.

When: In March, before it goes back outside, or in October after flowering, before you bring it in.

How:

• Each year, remove a few of the oldest, bare stems low down: this keeps the shrub young and full.
• Shorten overlong shoots to just above a whorl of leaves; three new shoots usually grow from there.
• Spare shoots that have visible flower buds at the tip.
• A badly neglected shrub can be cut back to 30–40 cm in March; it will then flower less for a year.

Caution: Wear gloves and long sleeves. Never burn the prunings, as the smoke is poisonous too, and do not leave them where children or animals can reach them.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings in water

From June to August: a non-flowering shoot 15 cm long, lower leaves removed, in a glass of water in a bright, warm place. Roots form after 3–6 weeks; then pot it up.

Semi-ripe cuttings

In July–August: 10–15 cm cuttings in moist cutting compost under plastic. Keep frost-free during the first winter.

Oleander: how does it get through the winter?

Hardy to −5 °C: protect in harsh winters.

• It can briefly take a few degrees of frost, to about −5 °C, but will not survive a Belgian winter outdoors.
• Leave it outside as long as there are only light frosts and bring it in before the first hard frost, usually in late October or November.
• Overwinter in a bright, frost-free place at 5–10 °C, such as a cold greenhouse, a light garage or a cool stairwell. A heated living room is too warm and too dry.
• Water sparingly in winter, do not feed, and check regularly for scale insects and spider mite.

Diseases and pests

• Scale insects: Brown or white scales on stems and leaves, and sticky foliage. Mainly in winter quarters. Wipe them off with a brush or cloth, wearing gloves.
• Aphids: Yellow aphids on young shoots and flower buds in summer. Blast them off with a strong jet of water; ladybirds help too.
• Red spider mite: Dull, finely speckled leaves in dry, warm air, especially in winter. Move the plant somewhere cooler and mist the leaves now and then.
• Bud drop: Buds that fail to open or drop off point to too little light, a dried-out root ball or a cold, wet summer. Give it more sun and water regularly.

Through the year

• January: Overwinter bright and cool. Water sparingly. Watch for scale insects.
• March: Prune and thin out. Repot if needed.
• April: Start feeding. In mild weather, put it out during the day to acclimatise.
• May: Pot up or repot. Move outside after mid-May.
• June: Flowering begins. Plenty of water and a weekly feed.
• July: Flowering. Water daily in hot weather. Root cuttings in water.
• August: Flowering. Last feed at the end of August. Take semi-ripe cuttings.
• September: Last flowers. Reduce watering.
• October: Light prune after flowering. Bring in before the first hard frost.
• November: Overwinter bright and cool at 5–10 °C.
• December: Water sparingly. Check for spider mite and scale insects.

Edible and useful

Not edible. Every part of oleander is highly poisonous to people and animals, even when dried: a few leaves can stop the heart of a child or pet. Never use the stems as skewers or as barbecue fuel (the smoke is poisonous too), wear gloves when pruning and keep the pot out of reach of children and pets. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• Oleander is the official flower of the city of Hiroshima: it was one of the first plants to flower again after the atomic bomb of 1945.
• On the undersides of the leaves, the breathing pores sit sunken in small, hairy pits. This means the plant loses little water in the heat.
• In the wild it often grows in riverbeds that dry out in summer: its roots then reach deep down for groundwater.