Alpine Thistle (Carduus defloratus)

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Sunlight Full sun to partial shade; thrives in bright, high-altitude light conditions with cool airflow

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Watering Water deeply when the top 2–3 cm of soil is dry; avoid waterlogging in heavy compacted soils

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Temperature Hardy to -15°C; tolerates frosty winters and cool alpine summer temperatures

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Leaf: Silvery-green basal rosette leaves with sharp, spiny margins and woolly undersides
Flower: Solitary purple-pink thistle heads, 3–5 cm in diameter, surrounded by spiny bracts
Stem: Erect, rigid stems covered in fine white hairs and small spines

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Watering

Keep soil consistently moist but not saturated during active growth

Fertilization

Diluted balanced feed once every 6 weeks. Use low-nitrogen feed to promote bloom production without excessive foliage growth

Eggshell powder topdress：Crush clean, fully dried eggshells into fine powder; sprinkle lightly on soil surface to add calcium without root burn

Pruning

Deadhead spent flower heads to prevent unwanted self-seeding
Remove yellowing basal leaves to maintain a tidy rosette appearance
Trim back dead stems to ground level in late autumn to prepare for winter dormancy

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Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: No listed toxicity to cats

Humans: Spines may cause mild skin irritation on contact; no systemic toxicity from ingestion

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Culture: N/A

Usage: Ornamental rock garden plant; nectar source for bees and butterflies