Plate No. 22

Star Cactus

Astrophytum asterias

"A spineless star flecked with white"

Native to

Tamaulipas, Mexico and southern Texas

Botanical illustration of Star Cactus
Astrophytum asterias — drawn from life
History

A brief account

A flat, eight-ribbed disc without spines — the ribs meet in a perfect star pattern crowned by a soft tuft of areoles. Poached to near-extinction in the wild, it is now widely propagated by seed and remains a treasured miniature.

How to care for

Star Cactus (Astrophytum asterias) grows best when its natural cycle of strong light, freely draining soil and measured watering is respected. Give it bright direct sun with midday protection. Water it according to its seasonal needs: lightly every two weeks in summer; dry in winter. Plant it in very mineral, with limestone chips. A container with an unobstructed drainage hole is essential, because moisture lingering around cactus roots can quickly lead to rot. Keep its temperature needs in mind: 5–35°c. cool winter rest needed. During active growth, check the compost before watering rather than following a rigid calendar, since heat, light and pot size all change how quickly it dries. Reduce watering during cool or dormant periods, keep the plant well ventilated, and wait until the growing medium is dry before watering again.

How to propagate

From seed only. Sow fresh seed on the surface of a fine, sterile cactus mix and keep it warm, lightly humid and out of harsh direct sun until germination. Once seedlings are established, increase ventilation gradually and allow longer intervals between watering to reduce the risk of damping off. Young cacti are especially vulnerable to excess moisture. Use a small pot with excellent drainage, provide bright filtered light while roots establish, and move the new plant gradually into the light, temperature and watering conditions preferred by a mature Star Cactus.
Cultivation

Quick tips for care & planting

Light
Bright direct sun with midday protection.
Water
Lightly every two weeks in summer; dry in winter.
Soil
Very mineral, with limestone chips.
Temperature
5–35°C. Cool winter rest needed.
Propagation
From seed only.