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Goat's Horn Cactus (Astrophytum capricorne)

Astrophytum capricorne is a solitary, evergreen perennial cactus that is globular when young and may later become ovoid to upright and columnar.

LightSources differ somewhat on light conditions: it prefers full sun to bright conditions and tolerates light shade; outdoors in warm regions it can take full sun, while greenhouse cultivation can use bright filtered light.
WaterDuring the growing season, water thoroughly after the growing medium dries; water can be given regularly in summer, while the winter dormancy period should be kept dry without waterlogging. The winter watering interval i
TemperatureIt is generally reported to be frost hardy, while resting cool and dry in winter. Based on few specialist sources, the cold minimum is reported at about 5 °C, and it is reported to tolerate brief light frost. A single so
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Goat's Horn Cactus illustration

Overview

Astrophytum capricorne is a solitary, evergreen perennial cactus that is globular when young and may later become ovoid to upright and columnar.

Origin and habitat

It occurs in dry to semi-arid environments with warm summers.

Characteristics

Sources differ on mature height, placing it at about 20–120 cm, while mature spread is 10–15 cm. It is reported to grow slowly. The large, funnel-shaped flowers are yellow to bright yellow with a red center or throat, and some sources describe them as fragrant. Flowering occurs in summer.

Light

Sources differ somewhat on light conditions: it prefers full sun to bright conditions and tolerates light shade; outdoors in warm regions it can take full sun, while greenhouse cultivation can use bright filtered light.

Watering

During the growing season, water thoroughly after the growing medium dries; water can be given regularly in summer, while the winter dormancy period should be kept dry without waterlogging. The winter watering interval is 30–90.

Temperature and dormancy

It is generally reported to be frost hardy, while resting cool and dry in winter. Based on few specialist sources, the cold minimum is reported at about 5 °C, and it is reported to tolerate brief light frost. A single source reports an upper temperature limit, and another reports a hardiness-zone range.

Growing medium and mounting

It needs a very fast-draining cactus mix; sources differ on suitable substrate conditions, describing sandy, gravelly, or loamy bases, with poor and slightly alkaline conditions outdoors also described, while acidic, neutral, or alkaline conditions are also reported as suitable.

Propagation

It can be propagated from seed.

Common problems

Poor drainage or persistently wet growing medium is unsuitable, while insufficient light may lead to poor growth and abnormal plant form.

Identification

The stem is green to gray-green and often bears white woolly flecks, with prominent ribs. Each areole may bear multiple slender, flattened, somewhat curved and strongly twisted yellow-brown to brown-black spines resembling goat horns.

Photos

Astrophytum capricorne
📷 Didier Descouens · CC BY-SA 4.0 · source
Astrophytum capricorne
📷 Oleksandr Shynder, some rights reserved (CC BY), uploaded by · CC BY · source

Sources