Growing Guide: Milk Thistle

Scientific Name Silybum marianum
Common Names Milk Thistle, St. Mary’s Thistle
Family Asteraceae (Sunflower Family)
Origin Mediterranean region
Plant Type Flowering Medicinal Herb
Life Cycle Annual to Biennial
Food Forest Layer Herb / Tall Groundcover Layer
Mature Size 3–5 ft tall, 2–4 ft wide
Light Full Sun
Water Needs Low; drought-tolerant once established
Harvest Season Summer to Early Fall (seeds)
Time to Harvest 90–120 days from seed
Self-Fertile Yes
Growth Rate Moderate to Fast
Zones USDA Zones 5–11
Florida Native No
Propagation Seeds
Seasonal Characteristics Annual or biennial; self-seeds readily, frost-sensitive