Euphorbia royleana Boiss.
Sullu Spurge, Royle's Spurge
Euphorbia royleana is a deciduous cactus-like shrub or small tree armed with short prickles along its stems. It grows to 16.5 feet (5 m) tall and has fleshy green segmented branches in whorls. The branches are up to 3 inches (7.5 cm) thick and have 5 to 7 ribs. They become leafless during hot and cold seasons. Leaves are alternate and apically clustered. The cyathia are small greenish-yellow and appear in almost stalkless clusters of 3 to 4 in leaf axils.
USDA hardiness zones 9b to 11b: from 25 °F (−3.9 °C) to 50 °F (+10 °C).
How to Grow and Care
Euphorbias are very easy to care for. These plants require a little pampering to become established, but once they are, they are self-sufficient. In fact, more die from too much care and watering than from neglect. Euphorbias need well-draining soil and lots of sunlight. They are not particular about soil pH, but they cannot tolerate wet soil. Unlike most succulents, Euphorbia does not handle long periods of drought well. It may need weekly watering during the summer. Water whenever the soil is dry several inches below the surface. Water deeply, but don't let them sit in wet soil, which can cause root rot. Add some organic matter or fertilizer to the planting hole. Feed with a half-strength fertilizer monthly if you are growing them in containers or your soil is poor.
These succulents can be grown from seed, but they can be difficult to germinate (or even find). They are usually propagated by cuttings. This can be tricky because of the exuding sap. Rooting hormone is recommended with Euphorbias. They tend to grow problem-free, but a few pests and diseases are to be alert for.
See more at How to Grow and Care for Euphorbia.
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