Lactuca virosa aka Wild Lettuce

Lactuca virosa belongs to the daisy family, Asteraceae. Its common names include wild lettuce, sleepwort, and opium lettuce. Its native range covers Europe, including Britain, and North Africa. It also reaches central Russia and western Asia. RHS confirms its native status in Britain and Ireland. It grows beside roads and canals, and on coastal banks. These sites often have lime-rich soil.

This plant grows as an annual or biennial. It reaches about 6 feet [1.8 metres] in height. Its whole plant contains a milky sap. Wounds release this sap, which dries and hardens in air. The sap contains lactucarium, a substance with a medicinal history. The supplied sources give no species-level detail on leaf shape. They also give no mature spread for garden plants.

Flowers appear from July to September. Each flower has both male and female organs. Insects pollinate them. Seeds ripen from August to September, overlapping with the flowering season. Growers can sow seed in place in spring or autumn. Cover the seed with only a thin layer of soil. PFAF reports that germination is often quick. This offers a direct way to raise plants in beds.

Give wild lettuce full sun and soil that drains well. It cannot grow in shade, according to PFAF. A light sandy loam suits it best. Sandy and loamy soils both fall within its stated range. It accepts mildly acid, neutral, and mildly alkaline soil. It prefers moist soil rather than a wet site. PFAF lists USDA hardiness zones 5–9 and reports frost tolerance. Its stated garden use is in cultivated beds. People also grow it as a medicinal crop across Europe.

PFAF records both food uses and a poisoning risk. It lists raw or cooked leaves as edible, with caution. The seeds yield an oil used in cooking. Its low food rating reflects limited edible value. These recorded uses do not establish that eating it is safe. PFAF calls the plant poisonous, though recorded poisonings are rare. It describes historical pain-relieving and sedative uses of the sap. These reports are not instructions for home treatment. PFAF does not flag weed potential for this species.