Milk thistle
Silybum marianum · Asteraceae
The gardener's calendar
Ideal time to plant milk thistle: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous, varied white and green
- Flowering
- June to September, violet-pink flowers
- Adult size
- 80 to 150 cm in height
- Growth
- Fast (annual or biennial plant)
- Hardiness
- Moderate, prefers temperate to warm regions
- Origin
- Mediterranean basin, Western Asia
- Soil type
- Well-drained, tolerant, undemanding
- Exposure
- Full sun
Care
Exposure
Milk thistle requires full sun exposure for optimal growth and generous flowering. It tolerates hot, sheltered locations. Avoid dense shaded areas where the plant becomes leggy and produces few flowers.
Watering
Water moderately after planting to establish roots. Once established, milk thistle is drought-tolerant thanks to its deep root system. Reduce watering in fall and winter. Avoid excessive moisture which promotes rot.
Soil and preparation
Milk thistle adapts to most soils, even poor or chalky ones. Well-drained soil is important to prevent root waterlogging. No specific amendments are necessary; the plant thrives even in basic conditions.
Nutritional needs
Apply a light balanced fertilizer in spring if soil is very poor. Generally, this hardy plant does not require regular fertilization. Excess nitrogen promotes lush foliage at the expense of flowers.
Pruning and maintenance
No pruning required. Remove spent flowers to encourage continuous flowering. At season's end, leave a few flower heads on the plant for natural self-seeding or seed harvesting.
Diseases and pests
Milk thistle is generally robust. Watch for powdery mildew in very humid conditions: improve air circulation. Some pests like slugs may affect young plants. No specific chemical treatment is usually necessary.
Did you know?
Milk thistle gets its name from the Virgin Mary according to Christian legend: the white spots on its leaves are said to result from maternal milk spilled during the flight to Egypt. Since ancient times, this emblematic Mediterranean thistle has been reputed to support liver health and remains a staple of European herbal medicine traditions.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
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Tips generated and checked by Viridia — adapt them to your local climate.