Common Sowthistle

Sonchus oleraceus is an annual leafy green in the daisy family, native to Europe and Western Asia and naturalised worldwide. Known variously as puha, sowthistle, or soft thistle, it produces rosettes of soft, lobed leaves with a milky sap and small yellow flowers. Young leaves have a pleasantly bitter, slightly earthy flavour reminiscent of chicory. It thrives in cool conditions with moderate moisture and tolerates light frost in its leafy stage.

Growing

Sow seeds into trays at a shallow depth of about 0.5 cm once soil temperatures reach at least 5 °C. Prick out seedlings when the first true leaves appear, spacing them 2.5 cm apart in the tray. Transplant into the garden when seedlings are 3–5 cm tall, setting plants 30 cm apart. Alternatively, direct-sow thinly and thin to 30 cm once established. Plants establish quickly and begin producing harvestable leaves within 4–8 weeks of transplanting.

Care

Keep soil consistently moist but not waterlogged; sowthistle tolerates brief dry spells but bolts rapidly under prolonged drought or heat. Apply a balanced liquid feed every two to three weeks to encourage lush leaf growth. Mulch around plants to retain moisture and suppress weeds. Pinch or cut any emerging flower stems promptly if continued leaf harvest is the goal, as flowering triggers bitterness and the end of productive leaf growth.

Harvest

Harvest by cutting individual outer leaves or the whole rosette with a sharp knife once plants are well established, leaving the root base intact so the plant regrows for a second and third cut. Young leaves and stalks are most tender and least bitter. Harvest before flower buds open for the mildest flavour. Once flowering begins freely, flavour becomes strongly bitter and the plant is best composted or left to self-seed.

In the kitchen

Young leaves can be eaten raw in salads where their gentle bitterness adds depth. For cooked preparations — traditional in Māori and Pacific Island cuisines — place leaves and stalks in cold water and rub vigorously until the cells break and green pigment releases into the water, reducing bitterness. Cook in a boil-up with pork bones, or sauté in butter, ghee, or lard to maximise uptake of fat-soluble vitamins and minerals. Historically, Captain Cook fermented puha like sauerkraut to prevent scurvy.

Storing

Use fresh leaves immediately after harvest for best flavour. Blanched and squeezed leaves can be refrigerated for up to 3 days. For longer storage, blanch briefly, squeeze dry, portion into bags, and freeze for up to 6 months. Dried leaves lose most texture but can be crumbled into soups and stews.