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Gymnocalycium spp.
chin cactus
Overview
Gymnocalycium spp. is a genus of about 70 species of small, globular cacti native to southern South America, including Argentina, Bolivia, Paraguay, Uruguay, and southern Brazil. The solitary or clustering stems are flattened to spherical, mostly 1.5–12 in (4–30 cm) across, ribbed, and grey-green to brownish, with horizontal chin-like swellings beneath each areole that give the common name chin cactus. Curved or straight spines, usually 3 to 10 per areole, run along the ribs. Funnel-shaped flowers 0.8–3 in (2–8 cm) across open near the crown in shades of white, cream, pink, red, or yellow-green, lacking hairs or bristles on the floral tube. The fruit is a small fleshy berry holding many seeds. Several species grow partly shaded beneath shrubs and grasses rather than in full exposure, which makes the genus more shade- and cold-tolerant than many cacti. G. mihanovichii includes the red and yellow chlorophyll-free forms grafted and sold as moon cactus. Plants are slow-growing and long-lived in cultivation.
Native Range
Native to southern South America, across Argentina, Bolivia, Paraguay, Uruguay, and southern Brazil, where plants grow in grassland, scrub, and rocky ground from lowlands to mountains, often sheltered among other vegetation.Suggested Uses
Grown as windowsill, greenhouse, and collection cacti in pots, and outdoors in rockeries and gravel gardens in frost-free and mild climates. The compact size suits small containers and dish gardens. Grafted coloured forms are grown as novelty houseplants.How to Identify
Appearance
Size & Dimensions
Height2" - 1'
Width/Spread2" - 1'
Bloom Information
Flowering occurs from late spring through summer, with funnel-shaped flowers opening near the crown over several weeks. Many species bloom while still young and flower repeatedly over the season. Each flower lasts several days, opening by day and closing at night.
Detailed Descriptions
Flower Description
White, pink, red, or yellow-greenFoliage Description
Grey-green to brownish stemsGrowing Conditions
Sun Requirements
Requires 4-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Care & Maintenance
Care Guide
Plants grow in bright light with some shade from harsh midday sun, in gritty, sharply drained cactus soil. Water is given freely during the spring-to-autumn growing season once the soil dries, then withheld through a cool, dry winter rest that encourages flowering. Most species tolerate light frost if kept dry, and many withstand more cold than typical desert cacti. Feeding is light, using a low-nitrogen fertiliser in summer. Overwatering and cold, wet soil cause root and stem rot, the main cause of loss. Plants are raised from seed or by removing offsets.Pruning
No pruning is required. Offsets can be removed for propagation, and shrivelled or rotted sections cut out with a clean blade. Grafted forms such as moon cactus may need rootstock offsets removed.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons