About Gymnocalycium baldianum (Speg.) Speg.
Gymnocalycium baldianum is a globose cactus, with a spherical or slightly flattened shape. Its depressed spherical shoots grow 4 to 10 cm tall, and reach diameters of 6 to 7 cm, with a maximum diameter of up to 8 cm. The skin color ranges from dark gray-green to blue-green, and it can sometimes be brown. It has 8 to 10 ribs with tubercle-shaped areoles, and does not produce central spines. Groups of 6 to 8 pale gray, curved marginal spines cover the areoles; most sources note 5 to 7 thin gray or brown marginal spines, which lie against the shoot surface and grow up to 1.5 cm long. These curved spines give the species its common name of spider-cactus. Like many cacti, it does not normally divide, but may develop offsets after several years of growth. Its funnel-shaped flowers grow near the apex of the plant, are red, pink or orange, and reach 3 to 5 cm long with a diameter of up to 6 cm. It produces dark gray-green, spindle-shaped fruits. This cactus is widespread in the Argentine province of Catamarca, where it grows at altitudes between 1000 and 2000 meters. It is easy to cultivate. It requires well-drained soil. During summer, water thoroughly, and allow the soil to dry completely before watering again, with monthly applications of cactus fertilizer. Keep the plant completely dry over winter; it can tolerate temperatures as low as −10 °C (14 °F), but it is best to protect it from frost. It needs full sun exposure in summer, and at minimum bright light during winter. This species has received the Royal Horticultural Society's Award of Garden Merit.
