Leonurus cardiaca aka Common Motherwort

Leonurus cardiaca, or motherwort, is an herb in the mint family. It is a perennial, so it lives for years. Its native range runs from Europe to Iran. People have brought it to many other parts of the world. It now grows across much of Canada and the continental United States. It grows by roads, at woodland edges, and on disturbed ground. It also grows on hedge banks, even those with gravel or lime-rich soil.

Garden plants often reach 2–4 feet [0.6–1.22 metres] tall. They spread to about 3 feet [0.91 metres]. RHS gives a taller range of 5–8.2 feet [1.5–2.5 metres]. The plant forms a bushy clump. Its upright stems have four angles. Pairs of dull green leaves grow on long stalks. The lower leaves have deep lobes with pointed tips. Higher leaves are smaller and have fewer lobes. The leaves die back for winter.

Small flowers bloom from June to August. They grow in whorls, or rings, around the upright stems. They can be lilac-pink, purple-pink, or white. Purple spots mark the flower lips. The blooms give nectar to insects that pollinate plants. RHS notes that honey from this nectar tastes strongly of mint. The flowers make motherwort useful in wildlife gardens and wildflower plantings.

Grow motherwort in part shade and moist soil that drains well. Missouri Botanical Garden favours rich soil and warns against dry sites. RHS also allows sun. It says the plant can cope with poor or heavy soil. It accepts chalk, clay, loam, and sand across a broad pH range. Published hardiness ratings are USDA zones 3–8 and RHS H4. Grow new plants from seed or rooted cuttings. You can also split clumps to make new plants. Cut back stems once the flowers fade. RHS reports no major pest or disease problems. Neither does Missouri Botanical Garden.

Motherwort can spread and become weedy in garden beds. Missouri Botanical Garden favours herb gardens over use just for looks. People have used it to treat heart complaints and nervous tension. Fresh or dried flowers flavour soups and beer, and make tea. The leaves also yield a dark olive-green dye. These uses do not mean the plant suits everyone. Skin contact can cause dermatitis, a form of skin rash. Its oil can make skin more sensitive to sunlight. Avoid it during pregnancy, as it can stimulate the uterus. Sharp teeth on the calyx can hurt grazing animals' mouths.