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Scientific: Nerium oleander
Common: oleander
Family: Apocynaceae
Origin: Mediterranean region

Pronounciation: NER-i-um o-lee-AN-der

Hardiness zones:
8-16, 12-23
USDA 8 (cold protected on south side of buildings), 9-11

Landscape Use: Multiple uses dependent on vigor of cultivar indcluding foundation, accent, informal hedge, background screen, street and parking lot tree standard.

Form & Character: Upright and rounded, versatile, colorful, stiff, low, rounded and mounding to strongly upright and open, often imposing, dangerous, Mediterranean.

Growth Habit: Evergreen, woody, perennial broadleaf shrub, moderate growth rate, vigor is cultivar dependent, ranging from 4- to 25-feet tall.

Foliage/Texture: Green, lanceolate, whorled, sessile, entire leaves to 4-inches long with prominent light green midveins, leaves taper to pointed tip; medium texture.

Flowers & Fruits: Flowers grow in terminal clusters at the end of a branch, 1 to 2 inches in diameter with a deeply 5-lobed fringed corolla around the central corolla tube, sometimes aromatic, many flower colors ranging from white to pink, salmon to burgundy. Fruit are a narrow pair of follicles to 9-inches long, which split open at maturity to release numerous, downy seeds that are wind dispersed in fall and winter. Rarely reseeds in southwest urban landscapes.

Seasonal Color: In Phoenix, oleander shrubs flower profusely from April to August being most brilliant and intense during May. Comparatively, oleanders along the southern and central California coast achieve peak flowering during July.

Temperature: Hardy to 15o to 20oF and absolutely thrives in hot summer desert areas. Individual fowers are heat tolerant in the following manner; white (most heat tolerant) > pink > salmon > red > deep red (most heat sensitive).

Light: Full sun (no shade).

Soil: Tolerates all but the most highly alkaline soils.

Watering: Oleander is surprisingly drought tolerant (its leaves have unique sunken stomata called stomatal crypts). But it does respond well to supplemental water given throughout the warmer times of the year. During winter, no supplemental water is needed.

Pruning: There are two horticulturally savy 'once-a-year' pruning strategies for oleander in Phoenix. For dwarf cultivars, prune if needed in late February to early March to any height. For large cultivars, it's best to prune in late February or August (expect rapid regrowth). Severe renewal pruning can be done once every two to three years.

Abusive pruning: Sadly, many Phoenix oleanders are frequently, I mean sheared, by the often well-meaning, but incompetent 'Horticultural clods of Phoenix', aka 'Hort clods' (naive individuals in possession of destructive gasoline or lithium-powered pruning tools). When oleanders are sheared frequently, then foliar disease transmission is heightened, water use efficiency is decreased, and over time plants perform poorly and will likely eventually die.

Propagation: Softwood cuttings (by far most common) or seed.

Disease and Pests: Oleander's "D and P" problems are well documented. They include: gall, oleander green and yellow aphids in spring, soft scale, and oleander leaf scorch caused by the oleander strain of Xylella fastidiosa which is a bacteria that colonizes xylem tissue and is vectored by xylem feeding sharpshooter insects such as the smoke tree sharpshooter. Oleander leaf scorch is a lethal disease that is a significant pathogen problem in southern California. It is spreading and is now present on oleander in the lower deserts of Arizona including Phoenix. There is NO effective control. Current import of California oleander nursery stock is quarantined.

Additional comments: In Phoenix, oleander is a common and highly versatile landscape shrub. Oleanders bloom over a long period of time from spring through summer and even into fall. Oleander's 21st century resurgence in popularity may be credited to the present abundance of dwarf cultivars. Oleander is also often used as a tree standard despite profuse basal suckering (remember, it is a shrub).

There are so many oleander cultivars! Here's just a partial list (there's more out there):

'Algiers', 'Big Pink', 'Big Red', 'California Red', 'Calypso', 'Cardinal', 'Carnival', 'Casablanca', 'Cherry Ripe', 'Compte Barthelemy', 'Double Pink', 'Double Red', 'Double Yellow', 'Dwarf Red', 'Eugenia Fowler', 'Franklin D. Roosevelt', 'Garbing Mall', 'General Pershing', 'Hardy Pink', 'Hardy Red', 'Hardy White', 'Hawaii', 'Hot Pink', 'Isle of Capri', 'Jannoch', 'Lady Kate', 'Lane Taylor Sealy', 'Little Red', 'Little White', 'Marrakesh' ('Moned'), 'Matilda Ferrier', 'Morocco' ('Monte'), 'Mrs. Roeding', 'Mrs. Runge', 'North Carolina State Yellow', 'Peach Blossom', 'Petite Pink', 'Petite Salmon', 'Pink Beauty', 'Red Velvet', 'Ruby Lace', 'Shari D', 'Shell Pink', 'Sister Agnes', 'Snow Frost', 'Sue Hawley Oakes', 'Sugarland', 'Tangier', 'Variegata', 'White Sands'

The Dark Side: But oleander has its dark side too and the operative word phrase to describe this is "deadly poisonous"! All oleander plant parts are poisonous. In AD 77, the Roman scholar, Pliny the Elder, described oleander as "an evergreen, bearing a strong resemblance to the rose tree, and throwing out numerous branches from the stem; to beast of burden, goats, and sheep it is poisonous, but for man it is an antidote against the venom of serpents" - Oh how wrong he was! One leaf, if ingested, might be lethal enough to kill a 150 pound adult. Children should be cautioned to NOT eat or touch foliage. In 2000, two toddlers in California were found dead in their cribs after chewing on oleander leaves. Smoke from burning oleander debris can be fatally toxic if inhaled. Always wear gloves and wash exposed body parts (hands, face, etc.) and clothes after pruning or handling this plant. The complete toxicology of oleander is only recently known.