Mammillaria glassii
Family: Cactaceae
​Common Name: Biznaga de Glass
Origin: Mammillaria glassii originates from Mexico, specifically the Madre Oriental mountain range, and Coahuila, Tamaulipas, and Nuevo Leon states, at altitudes of 1,450 – 2,250 meters.
Description: M. glassii is a small globular cactus that readily forms aggregations with numerous branches. Radial spines are white and covered densely with hair, while central spines are erect and hooked. In early spring, small funnel-shaped pink flowers are formed, developing green fruits and becoming pink to red when ripe.
  • Interesting Features:
    • Biznaga de Glass is one of the earliest species of Mammillaria to flower, blooming in late winter to early spring.
    • Although common in cultivation, this species is endangered in its natural habitat.
  • Uses: Mammillaria glassii is commonly used as an ornamental plant in xeriscape gardens. Additionally, various Mammillaria species have been used to treat ailments in Mexico – including dysentery, ear-ache, and poison. Other uses include as a purgative and snake repellant.

Cultivation and Care:
  • Watering: Low
    • As with other species of cacti, water sparingly when dry, increasing irrigation in summer and suspending during winter. Use a pot with very good drainage.
  • Soil: Plant M. glassii in a porous, well-draining cactus soil, pH 6.1-7.8, and repot every 36 months. To preserve the white color of spines, use a covering gravel.
  • Lighting: ​​To encourage the heaviest spine formation, provide as much light as possible, but be careful not to move from greenhouse conditions to direct sunlight immediately, as cacti can become sun burnt. After the summer heat has set in, move from direct sunlight and provide partial shade.
  • Propagation: M. glassii can be propagated from seed, offsets, and woody stem cuttings. Allow stems to callous before directly planting into soil, and sow seeds directly after the last frost. For offsets, remove when pups are 1/3 the size of the parent plant.
  • Cold Tolerance: 25°F, USDA Hardiness zones 9b to 11.
  • Special Accommodations: During the summer, feed with a high potassium fertilizer.

Sources:
  1. Llifle Encyclopedia of Cacti
  2. Cacti Guide
  3. Cactus Limon
  4. HROVAIN Exotica
  5. Dave’s Garden
  6. Garden