Euphorbia geroldii Rauh
Thornless Crown of Thorns, Thornless Euphorbia, Gerold's Spurge
Euphorbia geroldii is a beautiful semi-succulent shrub that grows up to 2 feet (60 cm) tall. It has no spines, unlike its thorned cousin Euphorbia milii. Leaves are glossy dark green, up to 3.2 inches (8 cm) long, and up to 1.2 inches (3 cm) wide. Flowers are coral red with a yellow center. This plant is almost in constant bloom.
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. 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 grow 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.
Learn more at How to Grow and Care for Euphorbia.
This species is endemic to Madagascar. Its natural habitat is subtropical or tropical dry forests. It is threatened by habitat loss.
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