Synonyms:

Gymnocalycium asterium var. minimum
Gymnocalycium obductum Piltz in Succulenta
Gymnocalycium stellatum var. minimum
Gymnocalycium stellatum var. obductum

Habitat:

Gymnocalycium ragonesei is native to the arid regions of Argentina, particularly thriving in the provinces of Catamarca and La Rioja. This cactus is typically found in rocky, mountainous areas where it grows at elevations ranging from 500 to 1,500 meters. The environment is characterized by sparse vegetation, providing little competition for resources. The soil is often sandy or gravelly, ensuring good drainage which is crucial for the health of the plant. Gymnocalycium ragonesei has adapted to survive in these tough conditions with infrequent, but occasionally heavy, rainfall interspersed with long dry periods.

Description:

Gymnocalycium ragonesei is a small to medium-sized, globular cactus that typically grows solitary but may occasionally form small clusters. The plant can reach up to 15 cm in height and 12 cm in diameter, featuring a green to blue-green body. The surface of the cactus is divided into 9 to 13 broad, rounded ribs that are adorned with areoles from which spines emerge. The spines are generally short, straight or slightly curved, ranging in color from white to yellowish or even brown, depending on age and exposure to sunlight. Gymnocalycium ragonesei typically has 3 to 7 central spines that are stouter, surrounded by 7 to 12 radial spines which are more slender and spread outward. Flowering in this species occurs from late spring to early summer, producing flowers that are white to pale pink, sometimes with a subtle greenish or reddish hue near the base. The flowers emerge from the top of the cactus, opening during the day and closing at night, lasting for several days. The fruit that follows is berry-like, fleshy, and greenish to reddish in color, containing several black seeds.

Cultivation:

Cultivating Gymnocalycium ragonesei requires simulating its native semi-desert habitat. This cactus prefers full sun to partial shade, with more shade in hotter climates to prevent sunburn. The ideal temperature range is between 10 to 30 degrees Celsius. During the winter months, it is essential to keep the plant cool and dry, ideally between 5 to 10 degrees Celsius, to encourage dormancy and flowering in the following season. The soil must be well-draining, typically a mixture of loam, sand, and gravel, or a commercial cactus mix amended with pumice or perlite. Watering should be regular in the summer, allowing the soil to dry out completely between waterings, but reduced significantly during the winter to prevent root rot. Fertilization should be done sparingly, only during the growing season, using a low-nitrogen cactus fertilizer diluted to half the recommended strength. Repotting should be undertaken every few years in spring to refresh the soil, being careful with the root system, which is not extensive but is sensitive to disturbance.

Propagation:

Propagation of Gymnocalycium ragonesei is typically done through seeds or by detaching offsets that occasionally develop around the base of the parent plant. Seeds should be sown in a sandy, well-draining soil mix, kept moist and warm until germination. Offsets can be carefully removed once they have formed their own roots, allowed to dry for a few days to form a callus, and then planted in similar soil conditions as adults.

Curiosity:

Gymnocalycium ragonesei is particularly noted for its attractive, almost symmetrical globular shape and its relatively large, showy flowers compared to the size of the plant. It is a popular species among cactus enthusiasts due to its ease of care, distinctive appearance, and the fact that it is less common in cultivation than some other Gymnocalycium species. This cactus is also appreciated for its slow growth and long lifespan, making it a rewarding plant for collectors who enjoy watching their specimens develop over many years.

Official Web Site:
www.giromagi.com

Italian Blog:
www.giromagicactus.com

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