Gymnocalycium ragonesei A.Cast.
Gymnocalycium asterium var. minimum, Gymnocalycium stellatum var. minimum
Gymnocalycium ragonesei is a small cactus with a flattened-globose, usually solitary stem with 7 to 10 ribs and clusters of almost hairlike spines. The stem slowly grows to 1 inch (2.5 cm) tall and 3 inches (7.5 cm) in diameter. The color of the stem varies by season, from grey-green and olive-green to purplish-brown.
The flowers are creamy-white with a reddish throat, appear in late spring, and remain open for up to 12 days. They are funnel-shaped, up to 2 inches (5 cm) long, and up to 1.8 inches (4.5 cm) in diameter.
USDA hardiness zones 9b to 11b: from 25 °F (−3.9 °C) to 50 °F (+10 °C).
How to Grow and Care
Some Gymnocalyciums are shade-seeking in the wild, among shrubs or grasses, while others grow completely exposed. Therefore, some will need light shading from the sun in the hottest months, but to overdo it, will result in the loss of flowers.
The potting medium's balance should be sufficient to allow good drainage so that the plants do not sit in soggy soil for more than a day or two after watering.
While the plants are growing well in the summer months, watering can be frequent (weekly for small plants in small pots) but always allowing the compost nearly to dry out before rewatering. Watering in the winter months at all is unwise and certainly not necessary. The difficult times are spring and autumn.
Those species which produce offsets can be readily propagated by cuttings. Gymnocalycium seed germinates well when fresh and will keep for a few years if stored in cold conditions.
See more at How to Grow and Care for Gymnocalycium.
Gymnocalycium ragonesei is native to Argentina.
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