Milk thistle is a biennial plant native to the Mediterranean region, which also indicates its preferred growing conditions. It thrives in a sunny location with lime-rich, well-drained soil. In the climate of the Netherlands and Belgium, milk thistle is usually grown as an annual. It is a fast-growing plant that can quickly become invasive in the garden. Milk thistle can also be used as a green manure crop. It is also known as Blessed Milk Thistle and Holy Thistle. Milk thistle produces the characteristic purple, thistle-like flowers. Its leaves are large, spiny, and dark green with distinctive white veins and marbled markings, edged with yellow spines. The stem is thick, ribbed, and hairy. Milk thistle belongs to the daisy family (Asteraceae), along with plants such as yarrow, wormwood, artichoke, French marigold, yellow chamomile, German chamomile, Roman chamomile, daisy, pot marigold (calendula), cornflower, endive, cosmos, sunflower, dandelion, oxeye daisy, globe thistle, ragwort, lettuce, chicory and cotton thistle.
The young leaf stalks are edible, although the spiny ends should be removed before consumption. The seeds can be used to make a tea that may help support normal liver function. They can also be ground and used as a coffee substitute, but excessive consumption of milk thistle is not recommended. Milk thistle may cause allergic reactions in people who are allergic to plants such as ragweed, artichokes, chrysanthemums, calendula, kiwifruit, or daisies. People with diabetes or endometriosis are advised to consult a doctor before using milk thistle. In some individuals, mild side effects such as dizziness, headaches, or digestive discomfort may occur. People taking medication should also consult their doctor or pharmacist before using milk thistle, as it may affect the action of certain medicines. Milk thistle is highly attractive to bees, butterflies, bumblebees, hoverflies, and birds. In particular, bullfinches and goldfinches enjoy feeding on its seeds. Milk thistle flowers from June through August. Non-hardy biennial. Height: 60 - 150 cm.
Outdoor sowing: March - September
Germination: 7 -14 days
Germination temp.: 16 - 22 °C
Sowing depth: shallow
Planting distance: 50 - 60 cm
Plant position: sunny and sheltered
Flowering period: June - August
Sow outdoors directly into the ground from March onwards and gently press the seeds into the soil. Milk thistle is a light germinator and the seeds should not be covered with soil. Keep the soil consistently moist and free of weeds. Once the seedlings are large enough to handle, thin them to a spacing of 50 - 60 cm. Plant milk thistle in a very sunny, sheltered location. It is not particular about soil type but does require well-drained soil. This plant self-seeds very easily, making it an excellent choice for naturalistic or wild gardens.
