Euphorbia grandicornis Goebel ex N. E. Br.
Cow's Horn, Cow's Horn Euphorbia, Big Horn, Big Horned Euphorbia, Big Horned Spurge
Euphorbia grandicornis subsp. grandicornis
Euphorbia grandicornis is a succulent shrub with erect 3- to 4-winged green branches with a zigzag pattern and paired spines along the edges. The branches are up to 6.6 feet (2 m) tall and 4 inches (10 cm) wide. Spines are in pairs, grey to brownish, and up to 3 inches (7.5 cm) long. The tiny leaves appear in summer between the spines, but they will drop off later. In late spring, brilliant yellow cyathia appear in groups of 3 along the tip of the stem. The central cyathium is stalkless and composed of only male flowers, while the other two are stalked and bisexual. Fruits are purple, quite attractive 3-lobed capsules.
The specific epithet "grandicornis" is a Latin adjective meaning "large-horned" and refers to the pairs of spines.
USDA hardiness zones 10a to 11b: from 30 °F (−1.1 °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 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 there are a few pests and diseases to be alert for.
Learn more at How to Grow and Care for Euphorbia.
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