Pronounciation: Yew-FOR-bee-a MIL-ee-eye

Hardiness zones
Sunset 12-24 (all zones as annual)
USDA 9-11 (all zones as annual)

Landscape Use: In Phoenix, crown-of-thorns is a textural and floral accent for partial- to full-shaded annual or perennial landscape borders, patio gardens, east-facing entryways, or as a container plant. Also used in bright, naturally-light indoor atriums. Otherwise, mostly used as a house plant in colder climates, but as an outdoor full sun perennial shrub/subshrub in coastal California.

Form & Character: Stiffly rounded to sprawling, coarse and brittle, colorful, cute, sometimes formal, but untouchable.

Growth Habit: Semi-woody to succulent, perennial subshrub or shrub growing to 6-feet tall with a sprawling and loose habit. Most contemporary cultivated varieties have a much reduced habit of growth and are very compact habit. Stems have copious pronounced spines that demand attention.

Foliage/Texture: Medium green to reddish, oval to elliptical-shaped, succulent leaves to 1.5-inches long, somewhat emphemeral to dormant during winter; medium coarse texture.

Flowers & Fruits: Very small yellow to red blooms, often in terminal clusters, subtended by much larger white, yellow to red bracts; fruits inconspicuous.

Seasonal Color: Flowers most heavily during spring and fall.

Temperature: Cold tolerant to only 30^oF and intolerant of extreme summer heat above 112^oF.

Light: Prefers light to full shade in Phoenix, eastern exposures are preferred.

Soil: Any soil type so long as well drained.

Watering: In Phoenix, regular supplemental water is needed, especially during summer.

Pruning: Any amount of stems at any time can be removed depending on situation. New dwarf cultivars need little to no pruning.

Propagation: Easy by stem cutting if latex exudate from the cut stems is first allowed to dry. Make sure to wear protective gloves when working with this plant!!

Disease and pests: None

Additional comments: Overall, crown-of-thorns is a plant in Phoenix with a relatively narrow range of uses because of the extreme desert climate, and as a result is not commonly seen in outdoor landscapes.

Toxicities and biomedical factoids: Stems contain a white, milky latex that is a dermal irritant. Moreover, if ingested, it can cause stomach pain, irritation of the throat and mouth, and vomiting. Additionally, crown-of-thorns has wide variety of secondary metabolites with biological activity such as antioxidant properties of ethanol extracts of thorns and stems.

Historical Perspective: Legend has it that crown-of-thorns was introduced to the Middle East in ancient times and was worn by Jesus Christ during His cruxifiction (John 19:2).