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 up to 6.6 feet (2 m) tall. The angular stems are winged on 3 to 4 corners and up to 4 inches (10 cm) wide. The edges are lined with grey to brownish, paired, fused spines up to 3 inches (7.5 cm) long. The stem either protrudes below the spines creating an undulating edge or lies flat below the spines. It constricts and then expands at regular intervals of about 6 inches (15 cm) long, forming a zigzag pattern. The minute leaves are produced between the spines and later drop off. The tiny, reduced flowers are arranged in an inflorescence known as a cyathium. The yellow cyathia resemble small, cup-shaped flowers and typically occur in groups of 3 along the tip of the stem. One cyathia is stalkless and composed of only male flowers, while the other 2 are stalked and bisexual. The dry, dehiscent fruits are purple capsules with 3 lobes.
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 they cannot tolerant 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. If you are growing them in containers or your soil is poor, feed with a half-strength fertilizer monthly.
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.
Subspecies, Varieties, Forms, Cultivars and Hybrids
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