Pennyroyal has been used for centuries in herbal medicine. Its main value is as a digestive tonic where it increases the secretion of digestive juices and relieves flatulence and colic.
The whole plant a strong spearmint smell. The flowers are very attractive to bees and butterflies.
A good companion plant for cabbages and tomatoes, helping to repel cabbage root fly and other burrowing insects.
The plant has a low spreading habit and can be used as a ground cover, though it is somewhat sparse in the winter and can be invaded by the more aggressive weeds. The growing or dried plant repels fleas, ants, moths, mice etc. Rats and mice intensely dislike the smell of mint. The plant was therefore used in homes as a strewing herb and has also been spread in granaries to keep the rodents off the grain. A strong infusion applied to the face will keep gnats away in the summer.
The aromatic leaves are used as an ingredient of pot-pourri.
An essential oil is obtained from the whole plant, used in soap making and as a cleanser for fabrics.
Succeeds in most soils and situations so long as the soil is not too dry. Plants are very quickly diminished by dry conditions. Prefers a stiff moist soil that is slightly acid. A sunny position is best for production of essential oils, but plants succeed in partial shade.
Sow spring in a cold frame. Germination is usually fairly quick. Prick out the seedlings into individual pots when they are large enough to handle and plant them out in the summer.
Leaves - raw or cooked. Used as a flavouring in salads or cooked foods. A spearmint-like flavour, though rather coarser, it is not used very often in Britain. A herb tea is made from the fresh or dried leaves. For drying, it should be harvested as the plant comes into flower.http://practicalplants.org/wiki/Mentha_pulegium