Horsemint
Mentha longifolia

Family: Lamiaceae or Labiatae

What it is like

Mentha longifolia is a PERENNIAL growing to 1 m (3ft 3in) by 1 m (3ft 3in). See above for USDA hardiness. It is hardy to UK zone 6 and is not frost tender. It is in flower from August to September, and the seeds ripen from September to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and can grow in heavy clay soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil. The plant can tolerates strong winds but not maritime exposure.

Height (m): 1

Where it is found

Waste places and damp roadsides.

Central and southern Europe, including Britain, Mediterranean region, Siberia.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 2

Leaves - raw or cooked. Peppermint-scented, they are used as a flavouring in salads, chutneys and cooked foods. A herb tea is made from the leaves. An essential oil obtained from the leaves and flowering tops is used as a food flavouring in sweets etc. A peppermint-like taste.

Condiment: the various plants that are used as flavourings, either as herbs, spices or condiments.

Tea: the various herb teas that can be used in place of tea, plus the genuine article.

Medicine

Rating: 2

Horsemint, like many other members of this genus, is often used as a domestic herbal remedy, being valued especially for its antiseptic properties and its beneficial effect on the digestion. Like other members of the genus, it is best not used by pregnant women because large doses can cause an abortion. The leaves and flowering stems are antiasthmatic, antispasmodic, carminative and stimulant. A tea made from the leaves has traditionally been used in the treatment of fevers, headaches, digestive disorders and various minor ailments. The leaves are harvested as the plant comes into flower and can be dried for later use. The essential oil in the leaves is antiseptic, though it is toxic in large doses.

Antiasthmatic: Treats asthma.

Antiseptic: Preventing sepsis, decay or putrefaction, it destroys or arrests the growth of micro-organisms.

Antispasmodic: Relaxes muscular spasms and cramps, calming nervous irritation.

Carminative: Reduces flatulence and expels gas from the intestines.

Stimulant: Excites or quickens activity of the physiological processes. Faster acting than a tonic but differing from a narcotic in that it does not give a false sense of well-being.

Other

Rating:

The leaves contain about 0.57% essential oil. It is sometimes used as a substitute for peppermint oil in confectionery. 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.

Essential: Essential oils that are used in perfumery, medicines, paint solvents, insect repellents etc.

Repellent: Plants that are said to deter but not necessarily kill various mammals, birds, insects etc.

Strewing: Plants, usually aromatic, that are strewn on the floor to give a nice smell, repel insects etc.

Attracts Wildlife: Plants noted for attracting wildlife

Food Forest: Plants for Edible Forest Gardens and Food Forests.

Scented Plants: Plants noted for their scent

How it is grown

An easily grown plant, it succeeds in most soils and situations so long as the soil is not too dry. Grows well in heavy clay soils. A sunny position is best for production of essential oils, but the plants also succeed in partial shade. There is some confusion over the name of this plant, it appears in the British flora but according to Flora Europaea it is not found in Britain. Sometimes cultivated for its leaves, there are some named varieties. Most mints have fairly aggressive spreading roots and, unless you have the space to let them roam, they need to be restrained by some means such as planting them in containers that are buried in the soil. Hybridizes freely with other members of this genus. The whole plant has a mint-like aroma. The flowers are very attractive to bees and butterflies. A good companion plant for growing near cabbages and tomatoes, helping to keep them free of insect pests. Members of this genus are rarely if ever troubled by browsing deer.

Propagating it: Seed - 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. Mentha species are very prone to hybridisation and so the seed cannot be relied on to breed true. Even without hybridisation, seedlings will not be uniform and so the content of medicinal oils etc will vary. When growing plants with a particular aroma it is best to propagate them by division. Division can be easily carried out at almost any time of the year, though it is probably best done in the spring or autumn to allow the plant to establish more quickly. Virtually any part of the root is capable of growing into a new plant. Larger divisions can be planted out direct into their permanent positions. However, for maximum increase it is possible to divide the roots up into sections no more than 3cm long and pot these up in light shade in a cold frame. They will quickly become established and can be planted out in the summer.

Best place to grow: Woodland Garden Sunny Edge; Dappled Shade; Shady Edge; Cultivated Beds;

Habit: Perennial

Hardiness: 5-9

Growth:

Soil: Light (sandy), medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

Although no records of toxicity have been seen for this species, large quantities of some members of this genus, especially when taken in the form of the extracted essential oil, can cause abortions so some caution is advised.

Its other names

Local names

Synonyms

M. sylvestris. M. incana.