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Yellow Oleander

Cascabela thevetia

Also called Lucky Nut, Be-still Tree, Mexican Oleander

Shrub Identified 1 time

About Yellow Oleander

Yellow Oleander is a fast-growing, heat-loving evergreen shrub known for fragrant, spiraled yellow blossoms and glossy narrow foliage. It thrives in hot, sunny spots and tolerates poor, dry soils with ease. Note that all parts of the plant are extremely poisonous if ingested.

Type: Evergreen shrub or small tree
Height: 8–15 ft
Spread: 6–10 ft
Sun: Full sun
Water: Low once established
Soil: Well-drained, sandy or loamy soil
Hardiness: Hardy to 25 °F
Flowers: May to October
Growth: Upright, rounded dense shrub
Toxicity: Extremely toxic to humans, cats, and dogs; contains dangerous cardiac glycosides
Native to: Mexico and Central America

How to recognise it

Glossy, narrow willow-like linear leaves
Funnel-shaped yellow flower with twisted, spiral petals
Milky sap produced when stems or leaves are broken
Bushy, multi-stemmed upright shrub habit

Caring for Yellow Oleander

Watering

Every 2 weeks

How often: Occasional deep soaking during prolonged heat
How much: About 1 in every two weeks if no rain falls
When: Morning
Tips: Very drought tolerant once established; avoid overwatering or waterlogged soil.

Feeding

How often: Once in early spring
What to use: Balanced slow-release fertilizer
When: Early spring at start of active growth
How: Scatter around the drip line and water into the soil

Pruning

When: Late winter or early spring before fresh growth begins
How: Thin out crossing branches and cut back shoots by up to one-third to maintain shape and density.
Tips: Always wear thick gloves and eye protection; the milky sap is an irritant and toxic.

Jobs it will ask for

Check stems for oleander caterpillars or scale Inspect the undersides of the dense foliage for small defoliating caterpillars or scale insects.
Clean up fallen seed pods and leaves Rake up any fallen nuts or foliage and dispose of them safely away from pets and children.

Through the year

Spring

Prune lightly to shape and apply a light dressing of balanced organic fertilizer.

Summer

Enjoy heavy flowering; provide supplemental water only during severe dry spells.

Autumn

Reduce watering and gather dropped seed pods to prevent accidental ingestion or unwanted self-seeding.

Winter

Protect roots with mulch in marginal climates where frost may occasionally occur.

What to watch for

Oleander caterpillar infestation: Hand-pick while wearing protective gloves, or spray with Bacillus thuringiensis (Bt) if feeding is severe.
Root rot from wet soil: Ensure planting location has sharp drainage and withhold irrigation during rainy or cool periods.

Reference photos

Compare what's in your garden with confirmed photos of Yellow Oleander.

Photos from iNaturalist contributors.

Written by Garden Rescue from photo identifications, in US units. Local advice from your extension service or garden centre beats a general guide.