Milk Thistle prefers moist, rich soil with full sun, but will tolerate part shade. A tap-rooted plant, it does not take to transplanting and does poorly in pots. It is best sown directly in the soil either in the early spring for a late summer harvest or in late summer, allowing the rosettes to overwinter (they’re hardy to -15°C) and then harvesting the ripe seed the following summer.
An annual or overwintering annual, native to the Mediterranean and now widely naturalized across the planet, Milk Thistle is a striking plant growing from 3 to 7 feet tall with large smooth, glossy green leaves edged with sharp spines and painted with veins of creamy white. According to tradition, these veins originated from the milk of the Virgin Mary falling upon a plant, hence the plant’s alternate names Mary Thistle, or Saint Mary's Thistle. It bears beautiful bee-loving, solitary, bright purple flower heads, which give rise to the brown-black seeds.
Gloves are recommended when harvesting! First, cut off the partially dried seedheads prior to their fully opening, collect them in a bin, and dry them further in the sun for several days. Then thresh the seedheads until they are fully broken apart, screen and winnow them until you’re left with just the seed. You can also reach over the tops of the plants and carefully pluck the seeds very cleanly when they are ready, paying attention to doing this before the wind takes them.
Milk Thistle seeds have long been known for their powerful regenerative effect on the liver. They are used internally in the treatment of liver and gall bladder diseases, jaundice, cirrhosis, hepatitis, cancer, and mushroom poisoning from various mushrooms, including Death Cap. The seeds are also known to have antioxidant, antiviral and anti-inflammatory properties; and when roasted, can be used as a coffee substitute.