Old Lady Cactus (Mammillaria hahniana)

Old Lady Cactus

Mammillaria hahniana

Its white wool and radial spines wrap like a soft shawl. Clumping succulent cactus; common name: Old Lady Cactus.

Full sun
1–2/week
Beginner
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Plant Needs

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Sunlight Full sun to bright indirect light; protect from intense midday summer sun to prevent sunscald
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Watering Water deeply only when the entire soil medium is completely dry; avoid standing water to prevent root rot
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Temperature Thrives in 15–30°C; tolerates brief light frost down to 5°C if kept completely dry
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Characteristics

  • Leaf: Modified into fine white radial spines and short brown central spines
  • Flower: Small, pale pink to white funnel-shaped blooms ringed around the cactus crown
  • Stem: Globular, covered in dense white woolly areoles between tubercles
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Care Guide

Watering

Water when soil is fully dry; allow excess water to drain completely

Fertilization

Diluted cactus fertilizer once monthly. Avoid fertilizing during winter dormancy to prevent stress

Eggshell powder topdressing:Grind dried, rinsed eggshells into fine powder; sprinkle lightly on soil surface to add calcium without risk of over-fertilization
Pruning
  • Remove dead, yellowed, or rotting stem tissue with sterile pruning shears
  • Thin overcrowded clumps in spring to improve airflow and reduce pest risk
  • Trim spent flower stalks to maintain a tidy appearance
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA confirmed non-toxic; no adverse effects if ingested or touched

Humans: No known toxic effects to humans; safe for handling and casual contact

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Garden Uses & Culture

Culture: N/A

Usage: Ornamental succulent for indoor windowsills, rock gardens, and succulent arrangements