Mentha longifolia aka Wild Mint

Mentha longifolia is a spreading herbaceous perennial in the mint family. Gardeners also call it horse mint or long-leaved mint. Its native range covers Europe, North Africa, and southwest Asia. It is not native to Britain or Ireland. Records place it on damp roadsides and disturbed ground. Its scent and edible leaves give it value in herb gardens.

Garden plants reach about 3.3–4.9 feet [1–1.5 metres] tall and wide. The RHS also describes plants reaching 3.9 feet [1.2 metres]. They reach their full size within two to five years. Suckers help the clump spread beyond its first planting spot. The hairy leaves range from green to grey-green. They have a mint scent with a musty note. The plant sheds its leaves rather than keeping them year-round.

Small flowers form branched spires that narrow towards their tips. Their colour ranges from pale purple to white. The blooms appear from the middle to late summer. This species suits cottage gardens, informal beds, and wildlife gardens. Its spreading habit needs thought when choosing a site. The RHS warns that its roots can become a nuisance. A deep container sunk into the ground can limit their spread. An open site can instead give the plant room to grow.

Grow it in sun or part shade with moist soil. The RHS recommends good drainage, though it also lists poorly drained sites. Chalk, clay, loam, and sand all fall within its range. It tolerates acid, neutral, and alkaline soils. The RHS rates its cold hardiness as H7. Plants can grow in exposed sites or sheltered spots. Sow seed or divide plants in spring or autumn. Cut plants back once flowering ends. Watch for caterpillars, froghoppers, and mint beetles. Powdery mildew and mint rust may also cause trouble.

The leaves can flavour raw dishes or cooked food. They also serve as an ingredient for herbal tea. Oil from leaves and flowering tops has uses in food flavouring. Plants For A Future records traditional uses for digestive complaints. These records do not establish that such treatments work. Its species account reports no recorded cases of toxicity. That absence alone does not prove safety. The same account advises against medicinal use during pregnancy.