Shrub · Apocynaceae
Oleander
Nerium oleander
A tough, drought-proof shrub hung with summer-long bloom, and every part of it dangerous: every part is dangerously poisonous.
Full sun
Every 7–14 days
USDA 8–10
5–20 ft · 1.5–5.9 m
Overview
Oleander is a fast-growing evergreen shrub whose branches stay clothed in green the year around, and it holds that green where drought, salt spray, and poor soil would strip other plants bare. Through the warm months it hangs heavy with clustered flowers in pink, white, or salmon, opening from late spring well into summer. Left to climb it reaches 20 feet (6 m) tall on many upright stems, though it takes hard pruning just as readily, which is why it is so often shaped into a dense hedge or screen.
The same hardy build carries a hidden danger. All of it, from the woody root to the open flower, holds cardiac glycosides that attack the heart, and it ranks among the most poisonous shrubs planted near homes. That poison does not fade as the leaves dry to brittle brown, nor in the smoke of burning clippings, nor in the water a cut stem has stood in.
The plant earns its place where its toughness shows and its poison stays out of reach. Kept clear of pastures, play areas, and vegetable beds, handled in gloves, and never burned, it does no harm. Given that care, it carries one of the longest, most reliable bloom seasons of any shrub, flower cluster after flower cluster through the heat.
Care
The short version: full sun and well-drained soil, a deep drink then a dry spell before the next, and a light shaping cut once the flowers fade. It asks little once established, but every part of it is poisonous, so the gloves stay on.
Light
Oleander opens the fullest, densest flush of flowers in full sun, and slips to a thinner, sparser bloom in partial shade. The stronger the direct light, the tighter the plant packs its foliage and the heavier the flower clusters ride on it.
Water
Water it well while it settles, then let the top half of the soil dry out before the next drink. A mature plant is genuinely drought-tough and takes poor, salty ground in stride, so it wants water only every 7 to 14 days at most. A plant kept in a container drinks less through winter.
Soil
It sinks roots into clay, loam, sand, or shallow rocky ground, and holds on even where the soil is poor or salty. Sharp drainage counts for more than rich earth, and it stays content across a wide pH band of 6.0 to 7.8.
Temperature
Oleander takes searing heat up to about 100°F (38°C) without a wilted leaf. It weathers a light freeze down to roughly 19°F (-7°C), but a harder cold snap blackens or kills the growth, so container plants come in or overwinter cool.
Humidity
Average outdoor humidity suits its leaves fine, with no figure to reach. Dry air and coastal salt spray leave the foliage unmarked, so humidity rarely needs managing.
Feeding
Feed it seasonally from spring through summer with a balanced general-purpose fertilizer. A plant in the open ground draws little once it settles, while a potted one takes up a regular light feed through the growing season.
Pruning
Shape it lightly after flowering, from late summer into early fall. The buds set on new growth, so a cut later than early fall strips out next year's flowers. Spent blooms come off, the gloves stay on for the whole job, and the clippings never burn.
Repotting
A container oleander steps up every 2 to 3 years, or sooner once roots coil around the pot, water runs straight through, or growth stalls. It moves into a slightly larger pot with fresh, sharp-draining mix, gloves on.
Size & spacing
The plant rises from about 5 to 19.5 feet (1.5 to 6 m) tall and spreads 6 to 10 feet (1.8 to 3 m) across, so a full-size hedge of it fills real space. Dwarf cultivars hold to a far smaller frame and settle into a large container.
When to plant
Oleander belongs to the mild end of the temperate range, roughly zones 8 to 10. Cuttings or seed start in late winter to early spring, young plants go out after the last frost, and the flower clusters open from late spring through late summer.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: late winter to early spring
- Plant: spring after last frost
- Harvest: late spring through late summer
Hardiness
USDA hardiness zones: 8–10
Temperature: down to -12°C
Troubleshooting
Oleander rarely gives much trouble, and most of what shows up marks the leaves rather than the whole plant. Match what you see below and deal with it early. The gloves stay on for any job that means touching the plant.
Leaves eaten to a lacework of bare veins
Groups of the oleander caterpillar, orange-bodied and studded with tufts of black hairs, chew through the leaf blades and leave a fine lacework of pale veins behind. They work a branch fast, so the green tissue vanishes and only the skeleton remains. Picking the caterpillars off by hand, gloves on, clears the colony, and any branch chewed to bare veins comes off with it. A heavy outbreak yields to Bacillus thuringiensis.
Fix:
- Hand-pick and destroy caterpillars (wear gloves)
- Remove and dispose of heavily infested branches
- Apply Bacillus thuringiensis (Bt) for severe infestations
Leaves glazed sticky and blackened, insects massed on the new growth
The tender new growth turns crowded with bright yellow oleander aphids, and now and then bumpy scale or white, cottony mealybugs pack in beside them. They leave a sticky, glazed film of honeydew, and over it spreads a dull black crust of sooty mold that darkens the leaf surface. A hard jet of water knocks the lighter clusters loose, and insecticidal soap or horticultural oil clears the rest. A second pass breaks the cycle, and the black film washes away to leave the leaves glossy again.
Fix:
- Spray off light infestations with a strong jet of water
- Apply insecticidal soap or horticultural oil to affected growth
- Repeat treatment to break the pest cycle and wash off sooty mold
Sharp brown and yellow blotches marking the leaves
Brown and yellow blotches with clean, sharp edges break up the smooth green of the leaves, the signature of a fungal leaf spot, though the flat black smudge of sooty mold from insect honeydew can print similar marks. Stripping the blotched leaves and clearing the fallen litter at the base takes the worst of it away. Opening the plant so air moves through it and keeping the leaf surfaces dry leaves the spores little room to take hold.
Fix:
- Remove and destroy affected leaves
- Improve air circulation and avoid overhead watering
- Clean up fallen debris around the plant
Toxicity
This is one of the most dangerous plants grown near a home. Every part holds cardiac glycosides that can stop a heart, and the poison stays in the dried leaves, in the burning smoke, and in vase water. A single leaf has killed children, and it is rapidly and often fatally toxic to cats, dogs, horses, livestock, and birds. It belongs well away from anyone who might taste it, and the clippings never get burned.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Severe
A single leaf taken from this plant puts a cat in real danger. The early signs are drooling, vomiting, diarrhea, and belly pain, and they give way to an irregular or racing heartbeat, weakness, and collapse. Even a small taste can prove fatal, so any contact is an emergency.
Dogs Severe
A dog that chews one leaf or stem faces the same grave risk. Drooling, vomiting, and diarrhea slide into dangerous heart rhythm changes, tremors, and sudden collapse. A vet is needed at once rather than watching to see how it goes.
Horses Severe
Horses are exquisitely sensitive, and only a few of the narrow leaves can kill one. Colic, drooling, and diarrhea arrive alongside a wildly abnormal heartbeat, muscle tremors, and collapse. Dried clippings blown into a paddock stay as deadly as the fresh green plant.
Rabbits Severe
The cardiac glycosides hit rabbits hard, and a tiny amount can stop the heart. Watch for gut pain, refusal to eat, weakness, and a faltering pulse. No nibble is safe, so oleander stays well out of reach.
Livestock Severe
Cattle, goats, and sheep are poisoned by the green leaves and by dried clippings raked into hay alike. Vomiting, colic, diarrhea, and a staggering heartbeat lead to collapse and sudden death. Many losses come from animals eating trimmings tossed over a fence.
Birds Severe
Birds are not spared, and the same heart toxin can kill them quickly. Look for weakness, a ruffled stillness, an erratic heartbeat, and sudden death. Poultry and pet birds belong away from every part of the plant.
People Caution
No part of oleander is edible, and a single leaf has been enough to kill a child. Swallowing any of it can cause vomiting, a dangerously irregular heartbeat, and death, while the sap irritates skin. Gloves go on, the clippings never burn, and children stay well away.
Wear gloves when handling or pruning; never burn clippings; wash hands after contact; keep all plant parts, prunings, and vase water away from pets, children, and livestock.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Oleander carries flowers across a range of colors and comes in a few sizes, from low dwarf forms to tall hedging types. These are some of the cultivars you are most likely to find.
Hardy Pink
A selection that opens pink flowers and withstands more cold than most, which makes it the safer choice in marginal zones.
Petite Salmon
A compact dwarf that carries soft salmon-toned blooms on a frame far shorter than the wild species, right for tight spots and large pots.
Sister Agnes
A vigorous cultivar with clean white flowers on tall, fast-climbing growth, long favored for screens and hedges.
How to propagate
Oleander is simple to multiply, and cuttings are by far the surest way to copy a plant you like. Both methods call for gloves, because every part you handle is poisonous.
Stem cuttingsEasy
Late spring through summer · 2-4 weeks to root
A cut stem is the easy way to make more oleander, and each one grows up true to the parent. Softwood or semi-hardwood pieces taken from late spring through summer push out roots in 2 to 4 weeks, even standing bare in a glass of plain water on a windowsill. Gloves stay on the whole time, because the cut stems and their sap are poisonous.
SeedModerate
Late winter to spring · Several weeks to germinate; seedlings vary
Seed is the slower and less certain route. Sown from late winter into spring, the seeds take several weeks to sprout, and the seedlings that rise often look nothing like the parent. The seeds carry the same toxin as the rest of the plant, so gloves stay on while handling them.
Myths
Only the leaves are dangerous, so the flowers, smoke, and vase water are harmless.
Every part of oleander is poisonous, from the bark, flowers, and fruit to the leaves, roots, sap, seeds, and stems. The danger does not fade as the plant dries to brittle brown, the smoke from burning clippings is toxic to breathe, and even the water a cut stem stood in can poison someone. A single leaf can be enough to kill a child or a pet.