Astrophytum myriostigma cv. Walnut is a horticultural cultivar of Astrophytum myriostigma distinguished by its unusually dark, nut‑brown epidermis and dense white flecking, giving it a “walnut shell” appearance.
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Bright sun — Full sun to bright indirect light; too much intense sun may scorch dark cultivars.
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Minimal watering — Let soil dry completely; water every 7–10 days in summer, much less in winter.
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Fast‑draining substrate — Sandy, gritty, cactus mix; avoid moisture retention.
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Temperature — Prefers warm, dry conditions; protect from frost.