Common Name: christplant
Type: Broadleaf evergreen
Family: Euphorbiaceae
Native Range: Madagascar
Zone: 10 to 12
Height: 3.00 to 6.00 feet
Spread: 1.50 to 3.00 feet
Bloom Time: Seasonal bloomer
Bloom Description: Green subtended by red or yellow bracts
Sun: Full sun
Water: Dry to medium
Maintenance: Medium
Flower: Showy
Leaf: Evergreen
Other: Thorns
Tolerate: Rabbit, Deer, Drought, Dry Soil, Shallow-Rocky Soil, Air Pollution
Culture
Winter hardy to USDA Zones 10-12 where plants are best grown in dry to medium moisture, well-drained soils in full sun. Plants react poorly to temperatures that dip below 35°F in winter. May survive in Zone 9 with protection. Appreciates some midday shade in hot summer climates. Plants are tolerant of poor soils, including rocky-sandy ones. Plants are also tolerant of dry soils, but regular applications of moderate moisture may result in better bloom with less leaf drop. Wet soils, particularly in winter, can be fatal. Best located in areas with good air circulation. Indoor plants need bright light and are best grown with a gritty soil-based potting mix. Propagate from tip cuttings. Wear gloves when working with this plant. Sticky white latex sap is poisonous (avoid contact with skin, mouth or eyes).
Noteworthy Characteristics
Euphorbia milii, commonly called crown of thorns, is a woody, succulent shrub that features (a) fleshy, bright green leaves, (b) inconspicuous flowers in clusters subtended by very showy petal-like red or yellow bracts and (c) thick sharp black thorns (to 1/2" long) which cover its water-storing branches and stems. In Madagascar, this shrub typically grows in a sprawling form to 5-6' tall. Outdoors in southern Florida, it typically grows to 3' tall. As a houseplant, it grows at best to 2' tall. Obovate bright green leaves (to 2 1/2" long) have wedge-shaped bases. Leaves are produced on new stem growth. Inconspicuous greenish true flowers, borne in cyathia, lack both petals and sepals, but are subtended by long-lasting, colorful, petal-like, bright red or yellow bracts which are exceptionally showy. In tropical and sub-tropical locations, flowers will bloom throughout the year, but primarily in spring and summer. In Florida, flowers bloom primarily in winter and spring. Houseplants often bloom from late winter well into fall. Many cultivars are available in commerce.
Genus name probably honors Euphorbus, physician to the King of Mauretania.
Specific epithet honors Baron Milius, one-time Governor of the island of Bourbon, who reportedly introduced this species to cultivation in France in 1821.
Common name refers to the belief by some that the crown of thorns worn by Jesus Christ at the crucifixion was made from stems of this plant.
Problems
Use gloves when working with this plant. Some gardeners experience skin rashes from contact with the toxic plant sap of euphorbias. Potential disease pests include leaf spots, stem and root rots and botrytis blight. Potential insect pests include scale, mealybug and thrips. Watch for mites.
Uses
Where winter hardy, it is an excellent selection for sunny beds, borders or rock gardens. Also useful as a low hedge or edger. Specimen. Container plant. Easy-to-grow indoor houseplant.