Edward F. Gilman, Dennis G. Watson, Ryan W. Klein, Andrew K. Koeser, Deborah R. Hilbert, and Drew C. McLean
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.
Figure 1. Full Form - Nerium oleander: oleander Credit: UF/IFAS
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
Figure 2. Range
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
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.
