The horseradish does not commonly produce viable seeds and the plant is usually propagated as cuttings from the roots or as natural extensions of the rhizome. Recent studies have shown that the sterility is associated with abnormal chromosomes, a relatively common mechanism of self-sterility in Brassicaceae, which suggests that A rusticana may be a hybrid of the other two species in the genus – A macrocarpa and A sisymbrioides.

Grow in light, fertile and deep, moist but well-drained soil in full sun. Water freely during the growing season. Can be invasive so grown in a pot.

Horseradish roots are pungent, antiseptic, aperient, digestive, diuretic, expectorant, rubefacient and stimulant. They can help control infections of gram-negative and gram-bacteria both internally and externally and are also active against pathogenic fungi. The plant is a powerful stimulant, whether used internally as a spur for the digestive system or externally as a rubefacient, although it should not be used internally by people with stomach ulcers or thyroid problems. The roots should be used in their fresh state - an infusion is used in the treatment of colds, fevers and flu and is of value in the treatment of respiratory and urinary tract infections, with weakly diuretic, antiseptic and expectorant properties. A sandwich of the freshly grated root is a traditional remedy for hay fever. Externally, a poultice made from the roots is used to treat pleurisy, arthritis and infected wounds, and to relieve the pain of chilblains. Some caution should be employed, however, because it can cause blistering. Horseradish can also normalize the arterial pressure and prevent the risk of blood clot formation. Sulfurous substances from horseradish enhance the elasticity of cerebral and coronary blood vessels, thus reducing the risk of an infarct or cerebrovascular accident.

The use of grated or powdered root of garden radish in herbal medicine also goes back at least to the 1st century AD when Pliny recommended the grated root to aid digestion and Dioscorides wrote of it as a ‘very hot herb’ and a diuretic. The learned German abbess, Hildegard of Bingen, recommended it for lung and heart diseases in the 12th century. Rubbing a poultice of the leaves and roots was claimed to relieve sciatica and to cure baldness. As Horseradish, Armoracia rusticana, an important use in some countries from the 16th century was to treat scurvy and worms as well as venomous bites, headaches, baldness, freckles, epilepsy, gout, and when mixed with colocynth for tinnitus [Matthiolius 1586]. The College’s Pharmacopoea Londinensis 1618 includes Raphanus domesticus and Raphanus sylvestris and their translation, as Garden Radish and Horseradish, respectively. Culpeper’s Physical Directory of 1649, based n the Pharmacopoeia Londinensis, gave the uses of both as inducing micturition and breaking renal stones; they were very indigestible, with Horseradish being the more powerful. By 1653, in his book, the English Physician, he added its use for scurvy, intestinal worms, and topically for aching joints, sciatica, and hard swellings of the liver and spleen. In Linnaeus’s Materia Medica (1749), as Cochlearia (with the synonym Raphanus rusticans), he recommends it as a diuretic, and for scurvy, anorexia, oedema, renal stones, and skin spots. In 1782, as Cochlearia armoracia, he added malaria, headache and arthritis. Similar general recommendations have been maintained until now, and, although it is not licenced as a herbal medicine in Britain or Europe, herbalists still employ Horseradish as a digestive aid and for coughs, bronchitis, high blood pressure and oedema. Dioscorides recommended applying the grated root of radish for sciatica and swallowing it to relieve colic, expel the afterbirth and to kill worms in children, as well as eating it after a heavy meal to aid digestion. In classical Greece it was sometimes employed as an aphrodisiac. With regard to horse radish Gerard, under the name Red Cole etc, repeated these uses and considered it an expectorant and as a means of increasing the flow of urine as a way to expel small bladder stones. Hildegard of Bingen 1098-1179) described it mixed with warm wine or water for lung diseases. Horseradish was listed in the Pharmacopoeia Londinensis 1618 following Gerard’s recommendations and as a treatment to be applied locally or swallowed for rheumatic joint pains. Culpeper in the English Physician 1653 (1649) gave similar uses and also considered it a treatment for ‘hard stoppings of the liver and spleen’. With other herbs the dried and powdered root in a honey and wine mixture was given for heartache and heart diseases and as a gargle for sore throats and loss of voice. It was popular in the 17th-18th centuries to treat scurvy. After early settlers introduced it to North America in the 16th-17th centuries native tribes employed it for toothache, as a digestive and urinary aid, to treat respiratory infections and topically to relieve toothache. Herbalists now recommend horseradish as a stimulant, an expectorant, rubefacient, antiscorbutic, a perspirant and mixed with wine and honey to treat chronic cough and flu. A poultice of the grated root is sometimes applied locally to relieve facial neuralgia.

The earliest descriptions have probably confused it with the closely related Radish (Raphanus raphanistrum subsp. sativus) as the variety with a white root. Pliny the Elder (AD23-79) called it Persicon napy and Dioscorides (AD40-90) named it SInapi persicum or Wild Radish. It was known to Linnaeus as Cochlearis in 1753. The confusing multiplicity of its names has been tabulated by Agneta et al (2013).The earliest use of the name ‘Horseradish’ is found in Gerard’s Herball of 1597 and the illustration and description there – ‘root long and thick and white of colour, in taste sharpe and very much biting the tongue like mustard’ and ’great leaves, long, broad, snipped about the edges … (like) … the great garden Docke [Rumex obtusiflolius]’ with ‘small white flowers’, is that of the plant we now call by that name. In that era it was mainly a garden plant but found wild in England on occasion. At the present time, no wild populations have been identified, except around populated areas. Gerard gives some of its other names, Raphanus rusticanus, Raphanus magnus, Raphanus sylvestris, mountaine radish, Great raisort, and in the north of England Redcole. Parkinson in his Theatrum Botanicum (1640) said that its north of England name was ‘Green Reddish’, reflecting the inconsistency of vernacular names. Turner’s Herbal (1568) and Parkinson both point out that the plants attributed to Dioscorides and Pliny (both 70AD) are not good matches for Horseradish, and are probably the ordinary garden radish, Raphanus raphanistrum subsp. sativus and charlock, Sinapis arvensis. Its genus name Armoracia might come from old Celtic where it means ‘Near the sea’, indicative of its preference for growing in damp areas, but is also used in Latin by Pliny (70AD) to mean ‘wild radish’ and the Latin for a ‘radish root’ is Raphanus. The origin of the first part of its usual English name ‘Horseradish’ is disputed. For some it represents the old Saxon word ‘Horse’ meaning ‘Strong, large or coarse’ and referring both to the size of the fully-grown root and the pungent, burning flavour. Others claim it comes from a very British misunderstanding of a foreign language. In German the plant, although one with different leaves, is called ‘Meerettich’. Literally that means ‘Sea radish’ and denotes its liking for damp areas and its similarity to the garden radish. Tabernaemontanus in 1588 Latinised this to Raphanus marinus. While Gerard does not mention the name ‘Meerettich’ he may have mistaken Meer for the German word Mähre, which translates as ‘Old Horse’, leading to the current English ‘Horseradish’. In east European countries it is widely known as ‘Chren’. Although not mentioned in the bible, by the 13th century it had replaced lettuce to become one of the bitter herbs eaten by Ashkenazi Jews at the start of Passover. Horseradish is a semi-hardy perennial that probably arose in south eastern Russia and neighbouring Persia and was brought by man to central Europe in the Middle Ages. The small whitish flowers sometimes produce fertile seeds but Petrus Crescentius’ Ruralia Commoda (ca. 1309) and Parkinson both note that this is rare. As Horseradish is probably a hybrid and these are often sterile due to various chromosomal abnormalities, it is usually propagated by root cuttings. Different clones show a range of leaf shapes, typical of hybrid swarms where one parent or the other may be more dominant. As it is not described by Dioscorides (70AD) or Theophrastus (370BCE), and Parkinson notes there is no Greek name for it, it is possible that it has only recently evolved and been discovered, and has spread via domestic and commercial cultivation, because of its agricultural importance in damper areas of the world as a food flavouring.

Traditionally it is one of the Bitter Herbs eaten by Jews at Passover as a reminder of their ancestor’s sufferings. The burning and biting taste of the grated root have led to its principal use in continental Europe since the 16th century and possibly earlier when mixed with vinegar as a sauce with meat, especially beef, and fish, and in pickles; it is then best known in many languages as Chren. Britain and the USA have more recently accepted it widely as a condiment following its introduction by European immigrants. The young leaves and prepared fresh root are sometimes added to salads.

The genus, and the related radish contain a relatively high concentration of glucosinolates, such as sinigrin, and the myrosinase enzyme. The intact root and leaves are almost odourless and tasteless but after injury, such as grating or an insect bite, the enzyme is able to release isothiocyanates, especially allyl isothiocyanate, which is responsible for the characteristic and greatly valued burning, hot and pungent flavour and smell. They provide the antibacterial preservative activity exploited in pickles, stews and soups. The smell of the volatile oil that can be prepared from the roots is due to released isothiocyanates and they will be lost by diffusion unless the gratings or pickles and sauces made from them are stored at a low pH in sealed containers. The evolutionary value of this property is as a deterrent of biting insects and grazing animals. In some cultivars the concentration of thio (sulphur) compounds is high enough to lead to discolouration of metal utensils used in cooking.

Large quantities of this plant can be poisonous due to its content of volatile oils. Traditional texts suggested possible thyroid function depression. Contraindicated with chronic nephritis, hepatitis, gastro-oesophageal reflux or hyperacidity conditions, and inflammatory bowel conditions. Avoid during pregnancy and lactation.

Toxic if ingested in large amount.