Shrub · Apocynaceae
Oleander
Nerium oleander
A tough, drought-proof shrub that blasts out bloom all summer long, with one hard rule 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 charges ahead where fussier plants stall, powering through drought, salt spray, and poor soil like they are nothing. It rewards a warm-climate garden with months of pink, white, or salmon flowers that run from late spring deep into summer. Turn it loose and it climbs to 20 feet (6 m) tall, yet it takes a hard cutback just as happily, which is why so many growers train it into a hedge or screen.
The very grit that makes it thrive also makes it dangerous. All of it, root to flower, carries cardiac glycosides that attack the heart, and it ranks among the most poisonous shrubs anyone plants near a home. That toxin holds its punch in dried leaves, in the smoke off burning clippings, and in the water a cut stem has been standing in.
Give it a smart spot and the poison stays clear of the wrong mouth. Keep it well away from pastures, play areas, and vegetable beds, work it in gloves, and never burn the trimmings. Grow it with that respect and it hands back one of the longest, most reliable bloom seasons you will get from any shrub.
Care
The short version: full sun and well-drained soil, water deeply but let it dry between drinks, and prune to shape the moment it finishes flowering. It runs on almost nothing once established, but every part of it is poisonous, so keep the gloves on.
Light
Oleander craves full sun and flowers its heart out in it, though it will coast along in partial shade with fewer blooms. Pour on the direct sun and it builds a denser plant and a heavier flush of bloom, so give it the brightest spot you have.
Water
Soak it regularly while it establishes, then let the top half of the soil dry out before the next drink. A grown oleander is genuinely drought-tough and laughs off poor, salty ground, so it wants watering only every 7 to 14 days at most. Back right off through winter for anything in a container.
Soil
It grabs hold in just about anything, from clay and loam to sand and shallow rocky ground, even where it is poor or salty. Drainage counts far more than rich soil, and it runs happy across a wide pH band of 6.0 to 7.8.
Temperature
Oleander takes on real heat, up to about 100°F (38°C), and never blinks. It rides out a light freeze down to roughly 19°F (-7°C), but a harder cold snap will damage or kill it, so growers haul container plants in or overwinter them cool.
Humidity
Average outdoor humidity suits it fine, with no number to chase. It powers through dry air and coastal salt spray, so this is one thing you can flat-out ignore.
Feeding
Feed it seasonally from spring through summer with a balanced general-purpose fertilizer. In-ground plants barely need a thing once they settle, while potted ones eat up a regular light feed through the growing season.
Pruning
Prune lightly to shape after flowering, from late summer into early fall. Buds set on new growth, so cut later than early fall and you torch next year's bloom. Deadhead the spent flowers, keep gloves on the whole job, and never burn the clippings.
Repotting
A potted oleander wants bumping 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 bigger pot with fresh, well-drained mix, gloves on, and it takes right off.
Size & spacing
Plants shoot 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 demands real room. Dwarf cultivars stay far smaller and slot neatly into a large container.
When to plant
Oleander thrives at the mild end of the temperate range, roughly zones 8 to 10. Kick off cuttings or seed in late winter to early spring, push young plants outside after the last frost, and the flowers keep firing 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 is a tough customer that rarely acts up, and what does show usually lands on the leaves rather than the whole shrub. Match what you see below and pounce on it early. Keep the gloves on for any job that means touching the plant.
Leaves chewed clean down to the veins
The oleander caterpillar rolls in as a group and can skeletonize a branch at speed, leaving lacework where full leaves stood. Jump on it early and it is a quick fix. Glove up, pick the orange, black-tufted caterpillars off by hand, and snip out any branch that is really overrun. When an outbreak surges, a hit of Bacillus thuringiensis knocks it flat.
Fix:
- Hand-pick and destroy caterpillars (wear gloves)
- Remove and dispose of heavily infested branches
- Apply Bacillus thuringiensis (Bt) for severe infestations
Tacky leaves turning black with insects packed on the new growth
Spot bright yellow oleander aphids swarming the fresh growth, sometimes with scale or mealybugs piling on, and they will pump out sticky honeydew that the black sooty mold feeds on. Good news: this stays skin-deep and the plant bounces right back. Hit the light infestations with a strong blast of water to knock them loose, then go in with insecticidal soap or horticultural oil. Come back for a second round to break the cycle, and the mold rinses clean once the bugs clear out.
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 off the plant
Brown or yellow spots with clean edges usually flag a fungal leaf spot, though insect honeydew and its sooty mold can fake the same look, so scan the plant before you act. Pull the marked leaves and sweep up whatever has dropped at the base. Open the plant up so air rushes through it, and keep water off the foliage, so the spores lose their footing and the plant powers back.
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, so grow it eyes wide open. Every part holds cardiac glycosides that can stop a heart, and the poison rides on 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 clear of anyone who might taste it, and never burn the clippings.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Severe
A cat that tastes any piece of this plant is in serious trouble, so move fast. The first wave brings drooling, vomiting, diarrhea, and belly pain, then an irregular or racing heartbeat, weakness, and collapse. Even a small taste can turn fatal, so treat any contact as an emergency.
Dogs Severe
One chewed leaf or stem lands a dog in the same danger, no exceptions. Drooling, vomiting, and diarrhea can flip fast into dangerous heart rhythm changes, tremors, and sudden collapse. Rush to a vet rather than waiting it out.
Horses Severe
Horses are wildly sensitive here, and just a few leaves can kill. Colic, drooling, and diarrhea hit alongside a badly abnormal heartbeat, muscle tremors, and collapse. Dried clippings blown into a paddock stay every bit as deadly as the living plant, so keep them out.
Rabbits Severe
The cardiac glycosides slam rabbits hard, and a tiny amount can stop the heart cold. Watch for gut pain, refusal to eat, weakness, and a faltering pulse. There is zero safe nibble, so keep oleander well out of reach.
Livestock Severe
Cattle, goats, and sheep go down to green leaves and dried clippings raked into hay alike. Vomiting, colic, diarrhea, and a staggering heartbeat drive on to collapse and sudden death. Plenty of livestock deaths trace to animals eating trimmings tossed over a fence, so bag them instead.
Birds Severe
Birds get no pass either, and the same heart toxin can drop them fast. Look for weakness, a ruffled stillness, an erratic heartbeat, and sudden death. Keep poultry and pet birds clear of every part of the plant.
People Caution
No part of oleander is edible, and a single leaf has been enough to kill a child. Swallow any of it and you risk vomiting, a dangerously irregular heartbeat, and death, while the sap stings skin. Wear gloves, never burn the clippings, and keep children well back.
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 rolls out in a whole spread of flower colors and a few sizes, from little dwarf forms to towering hedging types. Here are some of the cultivars you are most likely to track down.
Hardy Pink
A pink-flowered pick that shrugs off more cold than most, which makes it the smart bet for gardens riding the edge of the range.
Petite Salmon
A compact dwarf loaded with soft salmon blooms that keeps well under the wild species, perfect for tucking into tight spots and big pots.
Sister Agnes
A vigorous white-flowered cultivar that shoots up tall and fast, a longtime champ for screens and hedges.
How to propagate
Oleander multiplies with almost no effort, and cuttings are far and away the surest way to clone a plant you love. Whichever route you take, wear gloves, because every part you handle is poisonous.
Stem cuttingsEasy
Late spring through summer · 2-4 weeks to root
Cuttings are the fast, rewarding way to churn out more oleander, and every one roots true to the parent. Grab softwood or semi-hardwood stems from late spring through summer and they strike in 2 to 4 weeks, even standing in plain water on a windowsill. Keep gloves 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 takes the slower, wilder road, and the payoff is a bit of a gamble. Sow from late winter into spring and the seeds need several weeks to sprout, throwing seedlings that often look nothing like the parent. Handle them 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 packs poison, from the bark, flowers, and fruit to the leaves, roots, sap, seeds, and stems. Drying it changes nothing, the smoke off 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.