Pennyroyal

Description

European pennyroyal (Mentha pulegium) is an aromatic perennial herb in the mint family (Lamiaceae), also known as pudding grass, pennyrile, or mosquito plant. When crushed, the leaves release a powerful peppermint aroma, and the plant has a long history as a folk remedy, culinary herb, and natural insect repellent.

Although it was widely used in herbal medicine and cooking during the Middle Ages, it is now most valued for its ability to deter insects such as fleas and mosquitoes. Pennyroyal has also been used as a mint flavouring in herbal teas and foods.

Mentha pulegium contains pennyroyal oil, which is poisonous if ingested in sufficient quantities. It is considered toxic to cats, dogs, and horses, particularly if the leaves or essential oils are consumed.

How to identify

Pennyroyal (Mentha pulegium) is a low-growing, spreading plant reaching around 25–30cm in height, with soft, green, aromatic leaves held on square stems typical of the mint family.
From July to September, it produces clusters of small lilac to pale lavender-pink flowers arranged in whorls around the stem nodes, giving it a distinctive summer display.

How to grow

European pennyroyal grows best in moist but well-drained soil and prefers partial sunlight, although it will tolerate full sun if kept well watered. It is a spreading, ground-covering plant that suits damp borders, wildlife gardens, or pond margins, where its vigorous root system and strong scent can be used as a natural insect repellent.