San Pedro Cactus (Echinopsis pachanoi)

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Sunlight Requires full sun exposure for optimal growth; tolerate partial shade during extreme midday summer heat to prevent sunscald

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Watering Water deeply once every 1–2 weeks during active growth; allow soil to fully dry between waterings to avoid root rot

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Temperature Thrives in 15–30°C; tolerate brief light frost down to 5°C but avoid prolonged freezing conditions

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Stem: Ribbed, blue-green columnar stems with areoles bearing small spines
Flower: Large, white, fragrant nocturnal blooms up to 20 cm in length
Spines: Small, light brown spines clustered at evenly spaced areoles along stem ribs

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Watering

Water deeply when top 10–15 cm of soil is completely dry; avoid overwatering

Fertilization

Diluted cactus fertilizer applied once monthly. Discontinue fertilization during winter dormancy to prevent nutrient buildup

Eggshell powder topdressing：Crush dried eggshells into fine powder; lightly mix into the top 2 cm of soil to add calcium without altering soil pH

Pruning

Remove dead or damaged stem segments at the base to prevent rot from spreading
Trim overgrown lateral branches in early spring to maintain a compact, desired shape
Dispose of pruned material carefully to avoid accidental ingestion of psychoactive tissue

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Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: Non-toxic to cats; no known adverse effects from ingestion or contact

Humans: Contains mescaline, a psychoactive alkaloid; ingestion causes hallucinations, nausea, and cardiovascular disturbances

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Culture: Used in traditional Andean spiritual ceremonies for its psychoactive properties for over 3,000 years

Usage: Ornamental landscape cactus; traditional medicinal use (note: recreational psychoactive use is illegal in many regions)