Sea Urchin Cactus, Sand Dollar Cactus

Frost Tolerance: Hardy to 20° F (-6°C)

Sun Exposure: Full sun to keep it blooming.

Origin: Northeastern Mexico (Nuevo León, Tamaulipas), southern Texas

Growth Habits: Solitary globular cactus, up to 6 inches in diameter (15 cm); 6 to 8 ribs; no spines

Watering Needs: Little water, subject to root rot, keep very dry in winter

Propagation: Seeds that germinate rapidly. Some cultivars are grafted. They take up to 6 years to bloom.

Astrophytum asterias 'Super Kabuto' at Miles' to Go nursery. This is a form bred from a wild specimen.

The Astrophytum asterias is a popular spineless cactus. In the wild it is almost extinct, mostly due to habitat destruction. In the wild it decreases in size when lacking water and might be covered with dust during the dry season. The rain makes it swell and washes it, making it ready to enjoy the sunlight.
The white flecking is very variable from clone to clone. 'Super Kabuto' (second picture) is a Japanese cultivar with extremely abundant flecking.

Blooming Habits:
The Sea urchin blooms in summer at irregular intervals. The 2 inch wide flowers (5 cm) are yellow with a red center, and sweet scented. They are followed by spineless greyish-red fruits. Plants generally start blooming when they exceed one inch (2.5 cm) in diameter.

Culture:
Prefer alkaline, porous soil. Water slightly more in summer during its growing season. You can use half strength liquid fertilizer after the flower buds have formed.