Galeopsis tetrahit aka Hemp Nettle

Galeopsis tetrahit is an annual wildflower in the mint family, Lamiaceae. Its common names include common hemp nettle and false hemp. It is native to Europe, including Britain and Ireland. Its range reaches from Iceland and Russia to Spain and Macedonia. In Britain, it grows widely in disturbed places.

The plant has a bushy form and reaches 3.3 feet [1 metre] tall. It reaches maturity within one year. Its stems are square, and its oval leaves have toothed edges. The RHS lists its foliage as deciduous. Flowers grow in whorls from midsummer into autumn. They can be pinkish-red or white. The blooms supply both nectar and pollen for insects. This gives the plant value in wildlife gardens during its flowering season.

This species grows in farm fields, waste ground, and woodland clearings. Other recorded habitats include woods, fens, and wet heaths. In gardens, it suits sunny woodland edges and sites with dappled shade. The RHS lists both full sun and partial shade. It accepts clay or loam and acid, neutral, or alkaline soil. Soil should stay moist but drain well. It tolerates varied conditions where enough soil moisture remains. Both sheltered and exposed sites suit it. The RHS gives it a UK hardiness rating of H5. That rating covers winter lows of about −15 to −10°C.

Seed is the stated means of propagation. The plant needs no pruning, according to the RHS. The same source reports few usual pest or disease problems. PFAF flags it as a plant with weed potential. Its use in wildlife planting therefore comes with that caution. Its natural presence in cultivated ground also matters when choosing a site. The evidence supports its value for flower-visiting insects, rather than a food crop.

PFAF gives this species an edibility score of zero out of five. It warns that the plant is poisonous and can cause paralysis. It also records past medicinal uses for spasms and lung complaints. These reports should not be read as proof of safety. PFAF gives its medicinal value a score of one out of five. Non-food uses include a drying oil taken from the seeds. This oil has served as a leather polish. Fibre from the stems has been used to make cord.