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Milk Thistle

Silybum marianum

herb
verifiedReviewed by the GreenScout Team

Milk thistle is a tall, spiky biennial herb native to the Mediterranean, recognizable by its white-veined green leaves and purple-pink thistle flowers. The seeds are traditionally used for liver health and medicinal purposes. This hardy plant thrives in poor soil and is drought-tolerant once established.

Milk Thistle

Common Problems

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Care Guide

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Light
Full sun (6–8 hours daily)
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Water
Low water needs; water moderately during growth, then allow soil to dry between waterings. Drought-tolerant once established.
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Soil
Well-draining, poor to average soil. Prefers sandy, rocky, or loamy conditions; tolerates poor fertility.
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Fertiliser
Minimal fertilizer needed; a light feeding in spring is sufficient. Avoid high-nitrogen applications.
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Temperature
Cool to warm; prefers 50–75°F (10–24°C)
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Humidity
Low to moderate humidity; drought-tolerant and prefers dry conditions

Toxicity

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Generally non-toxic; safe for household members. May cause mild digestive upset if consumed in excess.

Common Diseases

Common Pests

Seasonal Care

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Resume regular watering and feeding as growth picks up.

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Peak growing season. Water and feed regularly.

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Reduce watering as growth slows. Stop heavy feeding.

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Minimal watering and feeding. Protect from frost if needed.

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Frequently Asked Questions

What are Milk Thistle seeds used for?

They're traditionally used for liver health and other medicinal purposes — the seeds are the most commonly harvested part of this tall, spiky biennial.

Why does my Milk Thistle thrive in poor soil?

As a hardy Mediterranean native, it's naturally drought-tolerant once established and actually prefers poor to average soil over rich, fertile conditions.

More from GreenScout

Milk Thistle Care Guide — Silybum marianum | GreenScout