Introduction

Oleander is a wonderful easy-care, rounded shrub or small tree, with long, dark green leaves and an abundance of single or double, sometimes fragrant flowers in shades of white, yellow, pink, red, or purple. Often trained into an attractive small tree, multi-branched oleander also does well as a quick-growing screen or large specimen planting. Planted on five to seven-foot centers, a row of oleander makes a nice screen for a large residence or other large-scale landscape. A dwarf shrub selection 'Petite' is most suited for residential landscapes due to its small size.

General Information

Scientific name: Nerium oleander

Pronunciation: NEER-ee-um oh-lee-AN-der

Common name(s): oleander

Family: Apocynaceae

USDA hardiness zones: 9A through 11 (Figure 2)

Origin: native to southern Asia and the Mediterranean

UF/IFAS Invasive Assessment Status: not assessed/incomplete assessment

Uses: reclamation; urban tolerant; screen; specimen; trained as a standard; container or planter; hedge; deck or patio; parking lot island < 100 sq ft; parking lot island 100-200 sq ft; parking lot island > 200 sq ft; sidewalk cutout (tree pit); tree lawn 3-4 feet wide; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; highway median

Description

Height: 10 to 18 feet

Spread: 10 to 15 feet

Crown uniformity: symmetrical

Crown shape: round, vase

Crown density: moderate

Growth rate: fast

Texture: medium

Foliage

Leaf arrangement: opposite/subopposite

Leaf type: simple

Leaf margin: entire

Leaf shape: linear, lanceolate

Leaf venation: pinnate

Leaf type and persistence: evergreen

Leaf blade length: 2 to 8 inches

Leaf color: dark green on top, paler green underneath

Fall color: no color change

Fall characteristic: not showy

Flower

Flower color: white, yellow, pink, red, or purple

Flower characteristics: very showy; emerges in clusters on terminal cymes

Flowering: primarily spring and fall, but may also occur year-round

Fruit

Fruit shape: elongated; pod

Fruit length: 3 to 6 inches

Fruit covering: dry or hard

Fruit color: black

Fruit characteristics: does not attract wildlife; not showy; fruit/leaves not a litter problem

Fruiting: summer and fall

Trunk and Branches

Trunk/branches: branches don't droop; not showy; typically multi-trunked; no thorns

Bark: gray and smooth, becoming shallowly fissured with age

Pruning requirement: needed for strong structure

Breakage: susceptible to breakage

Current year twig color: green

Current year twig thickness: thick

Wood specific gravity: unknown

Culture

Light requirement: full sun to partial shade

Soil tolerances: sand; loam; clay; alkaline; acidic; well-drained

Drought tolerance: high

Aerosol salt tolerance: moderate

Other

Roots: not a problem

Winter interest: no

Outstanding tree: no

Ozone sensitivity: unknown

Verticillium wilt susceptibility: resistant

Pest resistance: sensitive to pests/diseases

Use and Management

Growing well with only one yearly fertilization and springtime pruning, oleander is one of the easiest shrubs to care for. Sometimes suckers produced at the base of the plant will siphon off too much energy and flowering will be inhibited. These suckers should be pulled to remove them when they are young and succulent. The plant can be trained into a short central leader in the nursery and is often sold as a "standard" oleander. It grows into a round-headed ball, flowering year-round in USDA hardiness zones 9b through 11. Flowering is reduced in winter in USDA hardiness zone 9a. Every few years tops of trees in 9a are injured by cold.

All parts of the plant are poisonous so care must be taken when locating oleander near areas frequented by small children; burning of the trimmings will produce toxic fumes. Even chewing once or twice on a leaf or twig can send a person to the hospital.

Oleander survives drought well and is well-suited to growing on soil too poor for most other shrubs, even tolerating salt spray, brackish water, and alkaline soil. It thrives in full sun, appearing too lanky and flowering little if planted in partial shade. The oleander caterpillar can defoliate a plant within a week or two, and it is common in south and central Florida. It is commonly planted in highway medians as a no-maintenance plant. It grows following wet weather, slowing down in drought, but always looks good even in powder-dry soil.

Many cultivars are available. 'Calypso' has single, cherry red flowers and is very hardy; 'Compte Barthelemy' has double red flowers; 'Mrs. Roeding', double pink flowers; 'Sister Agnes', single pure white flowers; 'Isle of Capri', single, light yellow flowers; 'Hawaii', single salmon-pink flowers with yellow throats; and dwarf cultivars 'Petite Pink' and 'Petite Salmon', 'Variegata' and 'Variegatum Plenum' have variegated leaves.

Propagation is by cuttings.

Pests

Pest problems are scale and oleander caterpillar which can do quite a bit of damage to the foliage if left unchecked. Oleander caterpillar can defoliate a plant in a week or two.

Diseases

No diseases are of major concern.

References

Koeser, A. K., Hasing, G., Friedman, M. H., and Irving, R. B. 2015. Trees: North & Central Florida. University of Florida Institute of Food and Agricultural Sciences.

Koeser, A.K., Friedman, M.H., Hasing, G., Finley, H., Schelb, J. 2017. Trees: South Florida and the Keys. University of Florida Institute of Food and Agricultural Sciences.