Milk thistle is a useful plant to harvest, even though it is often considered a weed. It is a known antidote for death cap mushroom poisoning if it is taken within 24 hours of an incident. If you aren't suffering from poisoning, it's still a useful plant for the liver. Milk thistle contains silymarin, which can help to detoxify and regenerate liver cells. The chemical also blocks toxins from entering the cells. Milk thistle seed is often sold at health food stores in bulk or in products; however, you can harvest much more than just the seed from this plant.
Put on gloves to begin harvesting your milk thistle weeds to protect yourself from the prickly leaves and stem.
Use scissors to cut individual leaves at the base where they meet the stem. This important to remember when harvesting milk thistle leaves. Cut the prickly part of the leaves from the edge of the leaves. You can use young leaves raw in salad, or cook the larger leaves like spinach.
Cut down the stalk of your plants to about 2 inches from the ground to harvest it as a vegetable. Leave some of the stalks so you can gather seeds in the fall. The skin can be removed from the stalk, which is then soaked overnight and eaten like celery.
Wait until half of the flower heads begin to dry in late fall to harvest the seeds. Remove the seed head with scissors. Take off the umbrella-shaped pappus to reveal the seeds.
Remove the seeds; place them on a screen. Shake the seed gently back and forth to loosen and remove any hairs sticking to the seeds. Clean your seeds thoroughly under running water.
Pat your seeds dry with a towel. Spread them out evenly on a cookie sheet. Put the seeds in a cool, dry location for a week. You can use ground seeds on salads or in smoothies after they have dried.
Harvest the roots of your milk thistle plants in their second year of growth by digging in the soil around your plant's roots with a hand shovel until you can pull them up. Check your progress to be sure you are getting around the entire root without breaking it. You can eat the root raw or cooked.