Shrub · Apocynaceae
Oleander
Nerium oleander
A tough, drought-proof shrub with summer-long bloom and a warning attached: 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 that thrives where little else will, shrugging off drought, salt spray, and poor soil. It earns its place in warm-climate gardens with months of pink, white, or salmon flowers from late spring well into summer. Left alone it can reach 20 feet (6 m) tall, but it takes hard pruning just as readily and is often kept as a hedge or screen.
What makes it easy to grow also makes it dangerous. All of it, root to flower, holds cardiac glycosides that attack the heart, and it ranks among the most poisonous shrubs people plant near homes. The toxin does not weaken in dried leaves, in the smoke of burning clippings, or in the water a cut stem has stood in.
Grow it where its toughness pays off and its poison cannot reach the wrong mouth. Keep it clear of pastures, play areas, and vegetable beds, handle it with gloves, and never burn the trimmings. Treated with that respect, it gives you one of the longest, most reliable bloom seasons of any shrub.
Care
The short version: full sun and well-drained soil, water deeply but let it dry between drinks, and prune to shape after it flowers. It asks for very little once established, but every part of it is poisonous, so handle it with gloves.
Light
Oleander wants full sun to bloom its best, though it will get by in partial shade with fewer flowers. The more direct sun it gets, the denser the plant and the heavier the flush of bloom.
Water
Water regularly while a plant is getting established, then let the top half of the soil dry out between drinks. Mature oleander is genuinely drought-tough and copes with poor, salty ground, so it needs watering only every 7 to 14 days at most. Ease off through winter for any plant kept in a container.
Soil
It is not fussy about soil and grows in clay, loam, sand, or shallow rocky ground, even where it is poor or salty. Good drainage matters more than richness, and it is happy across a wide pH band of 6.0 to 7.8.
Temperature
Oleander handles real heat, up to about 100°F (38°C), without complaint. It takes a light freeze down to roughly 19°F (-7°C), but a harder cold snap will damage or kill it, which is why container plants are moved in or overwintered cool.
Humidity
Average outdoor humidity suits it fine, with no target to hit. It puts up with dry air and coastal salt spray, so this is rarely something to manage.
Feeding
Feed seasonally from spring through summer with a balanced general-purpose fertilizer. Plants growing in the ground need very little once they have settled in, while those in pots benefit from a regular light feed during the growing season.
Pruning
Prune lightly to shape after flowering, from late summer into early fall. Flower buds form on new growth, so cutting back later than early fall costs you next year's bloom. Deadhead spent flowers, wear gloves for the whole job, and never burn the clippings.
Repotting
Container oleander needs moving up every 2 to 3 years, or sooner if roots circle the pot, water runs straight through, or growth stalls. Step it into a slightly larger pot with fresh, well-drained mix and gloves on.
Size & spacing
Plants range from about 5 to 19.5 feet (1.5 to 6 m) tall and spread 6 to 10 feet (1.8 to 3 m) wide, so a full-size hedge needs real room. Dwarf cultivars stay far smaller and fit a large container.
When to plant
Oleander suits the mild end of the temperate range, roughly zones 8 to 10. Start cuttings or seed in late winter to early spring, set young plants out after the last frost, and the flowers carry on 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 lands on the leaves rather than the whole plant. Match what you see below, then deal with it early. Keep your gloves on for any job that means touching the plant.
Leaves chewed down to bare veins
The oleander caterpillar feeds in groups and can strip a branch fast, leaving a lacework of skeletonized leaves. Pick the orange, black-tufted caterpillars off by hand with gloves on, and cut away any branch that is heavily infested. For a bad outbreak, treat with Bacillus thuringiensis.
Fix:
- Hand-pick and destroy caterpillars (wear gloves)
- Remove and dispose of heavily infested branches
- Apply Bacillus thuringiensis (Bt) for severe infestations
Sticky leaves coated in black mold with tiny insects underneath
Bright yellow oleander aphids, or sometimes scale and mealybugs, cluster on the new growth and drip sticky honeydew that turns black with sooty mold. Blast light infestations off with a hard jet of water, then treat the rest with insecticidal soap or horticultural oil. Repeat the treatment to break the cycle and wash the mold away.
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
Spotted leaves dropping from the plant
Brown or yellow spots with clean margins point to a fungal leaf spot, though insect honeydew and its sooty mold can leave similar marks. Strip off the affected leaves and clear any fallen debris around the base. Open the plant up for better airflow and keep water off the foliage so spores have less chance to spread.
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 you can grow near a home. Every part holds cardiac glycosides that can stop a heart, and the poison stays in dried leaves, in 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. Keep it well away from anyone who might taste it, and never burn the clippings.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Severe
A cat that nibbles any part of this plant is in real danger. Watch for drooling, vomiting, diarrhea, and belly pain, followed by an irregular or racing heartbeat, weakness, and collapse. Even a small taste can prove fatal, so treat any contact as an emergency.
Dogs Severe
Dogs face the same grave risk from a single chewed leaf or stem. Drooling, vomiting, and diarrhea give way to dangerous heart rhythm changes, tremors, and sudden collapse. Get to a vet at once rather than waiting to see how it plays out.
Horses Severe
Horses are exquisitely sensitive, and only a few leaves can kill one. Colic, drooling, and diarrhea come on alongside a wildly abnormal heartbeat, muscle tremors, and collapse. Dried clippings blown into a paddock are just as deadly as the living plant.
Rabbits Severe
The cardiac glycosides hit rabbits hard, and a tiny amount can stop the heart. Expect gut pain, refusal to eat, weakness, and a faltering pulse. There is no safe nibble, so keep oleander well out of reach.
Livestock Severe
Cattle, goats, and sheep are poisoned by green leaves and by dried clippings raked into hay alike. Vomiting, colic, diarrhea, and a staggering heartbeat lead to collapse and sudden death. Many livestock deaths 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, ruffled stillness, an erratic heartbeat, and sudden death. Keep poultry and pet birds 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. Wear gloves, never burn the clippings, and keep children 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 comes in a range of flower colors and a few sizes, from dwarf forms to tall hedging types. These are some of the cultivars you are most likely to find.
Hardy Pink
A pink-flowered selection prized for taking more cold than most, which makes it the safer choice in marginal zones.
Petite Salmon
A compact dwarf with soft salmon blooms that stays well below the size of the wild species, handy for tight spots and large pots.
Sister Agnes
A vigorous white-flowered cultivar that grows tall and fast, 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. Whichever method you choose, wear gloves, because every part you handle is poisonous.
Stem cuttingsEasy
Late spring through summer · 2-4 weeks to root
Cuttings are the easy way to make more oleander, and they root true to the parent. Take softwood or semi-hardwood stems from late spring through summer and they take hold in 2 to 4 weeks, even standing in plain water on a windowsill. Wear gloves the whole time, because the cut stems and their sap are poisonous.
SeedModerate
Late winter to spring · Several weeks to germinate; seedlings vary
Growing from seed is the slower, less certain route. Sow from late winter into spring and the seeds take several weeks to sprout, with seedlings that often look nothing like the parent plant. Handle the seeds with care and keep gloves on, since they carry the same toxin as the rest of the plant.
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 when the plant dries, 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.