Garlic (Allium sativum) is a species of bulbous flowering plants in the genus Allium. Its close relatives include the onion, shallot, leek, chives, Welsh onion, and Chinese onion. Garlic is native to Central Asia, northeastern Iran and the foothills of Himalayas. It has naturalized in many other parts of the world, including Mediterranean Europe and China. There are two subspecies and hundreds of varieties of garlic.
Garlic has been used for thousands of years as a seasoning, culinary ingredient, and traditional medical remedy. It was known in many ancient civilizations, including the Babylonians, Egyptians, Jews, Romans, and Chinese, and remains significant in many cuisines and folk treatments, especially across the Mediterranean and Asia. Sulfur compounds give garlic its pungent odor and flavor. There is clinical evidence to indicate that consuming garlic has health benefits.
Garlic is cultivated in a variety of climates and countries; China was the largest producer in 2024, accounting for 73% of the world's supply, according to the United Nations FAOSTAT.
Description
Garlic is a perennial flowering plant that is native to Central Asia. It grows from a bulb, with a tall, erect flowering stem that reaches up to . The leaf blade is flat, linear, solid, and approximately wide, with an acute apex.
The plant may produce pink to purple flowers from July to September in the Northern Hemisphere. The bulb has a strong odor and is typically made up of 10 to 20 cloves. The cloves close to the center are symmetrical, and those surrounding the center can be asymmetrical. Each clove is enclosed in an inner sheathing leaf surrounded by layers of outer sheathing leaves. If garlic is planted at the proper time and depth, it can be grown as far north as Alaska. It produces hermaphroditic flowers. It is pollinated by butterflies, moths, and other insects.
Chemistry Fresh or crushed garlic yields the sulfur-containing compounds allicin, ajoene, diallyl polysulfides, vinyldithiins, and , as well as enzymes, saponins, flavonoids, and Maillard reaction products when cooked, which are not sulfur-containing compounds.
The phytochemicals responsible for the sharp flavor of garlic are produced when the plant's cells are damaged. When a cell is broken by chopping, chewing, or crushing, enzymes stored in cell vacuoles trigger the breakdown of several sulfur-containing compounds stored in the cell fluids (cytosol). The resultant compounds are responsible for the sharp or hot taste and strong smell of garlic. Some of the compounds are unstable and continue to react over time.McGee, pp. 310–311
Among alliums, garlic has by far the highest concentrations of initial reaction products, making garlic much more potent than onion, shallot, or leeks. Although many humans enjoy the taste of garlic, these compounds are believed to have evolved as a defensive mechanism, deterring animals such as birds, insects, and worms from eating the plant.
Numerous sulfur compounds contribute to the smell and taste of garlic. Allicin has been found to be the compound most responsible for the "hot" sensation of raw garlic. This chemical opens thermo-transient receptor potential channels that are responsible for the burning sense of heat in foods. The process of cooking garlic removes allicin, thus mellowing its spiciness. Allicin, along with its decomposition products diallyl disulfide and diallyl trisulfide, are major contributors to the characteristic odor of garlic, with other allicin-derived compounds, such as vinyldithiins and ajoene.
Taxonomy Identification of the wild progenitor of common garlic is difficult due to the sterility of its many cultivars, which limits the ability to cross test with wild relatives. Genetically and morphologically, garlic is most similar to the wild species Allium longicuspis, which grows in central and southwestern Asia. However, because A. longicuspis is also mostly sterile, it is doubtful that it is the ancestor of A. sativum. Other candidates that have been suggested include A. tuncelianum, A. macrochaetum, and A. truncatum, all of which are native to the Middle East.
Allium sativum grows in the wild in areas where it has become naturalized. The "wild garlic", "crow garlic", and "field garlic" of Britain are members of the species A. ursinum, A. vineale, and A. oleraceum, respectively. In North America, A. vineale (known as "wild garlic" or "crow garlic") and Allium canadense (known as "meadow garlic", "wild garlic", or "wild onion") are common weeds in fields.McGee p. 112 So-called elephant garlic is actually a wild leek (A. ampeloprasum) and not a true garlic. Single clove garlic (also called pearl or solo garlic) originated in the Yunnan province of China.
Subspecies and varieties There are two subspecies of A. sativum, ten major groups of varieties, and hundreds of varieties, or cultivars. A. sativum var. ophioscorodon (Link) Döll, called Ophioscorodon or hardneck garlic, includes porcelain garlics, rocambole garlic, and purple stripe garlics. It is sometimes considered to be a separate species, Allium ophioscorodon G.Don. A. sativum var. sativum, or softneck garlic, includes artichoke garlic, silverskin garlic, and creole garlic.
There are at least 120 cultivars originating from Central Asia, making it the main center of garlic biodiversity.
Some garlics have protected status in the UK and the EU, including:
Name SourceAglio Rosso di Nubia (Red Garlic of Nubia)Nubia-Paceco, Provincia di Trapani, Sicily, ItalyAglio Bianco PolesanoRovigo, Veneto, Italy (PDO)Aglio di VoghieraFerrara, Emilia-Romagna, Italy (PDO)Ail blanc de LomagneLomagne in the Gascony, France (PGI)Ail de la DrômeDrôme, France (PGI)Ail rose de Lautrec, a rose/pink garlicLautrec, France (PGI)Ail violet de CadoursCadours, France (PDO)Ajo Morado de Las Pedroñeras, a rose/pink garlicLas Pedroñeras, Spain (PGI) 金鄕大蒜 Jīn Xiāng Dà SuànChina (PGI) Taşköprü SarımsağıTurkey (PDO)
Etymology The word garlic derives from Old English, garlēac, meaning gar (spear) and leek, as a 'spear-shaped leek'.
Ecology Garlic plants are usually hardy and not affected by many pests or diseases, however, a pest that damages its seeds are Delia platura, commonly known as seed corn maggots. Garlic plants are said to repel rabbits and moles. The California Department of Food and Agriculture conducts a certification program to assure freedom from nematode and white rot disease caused by Stromatinia cepivora, two pathogens that can both destroy a crop and remain in the soil indefinitely once introduced. Garlic may also suffer from pink root, a typically non-fatal disease that stunts the roots and turns them pink or red; or leek rust, which usually appears as bright orange spots. The larvae of the leek moth attack garlic by mining into the leaves or bulbs.
Botrytis neck and bulb rot is a disease of onion, garlic, leek and shallot. Botrytis allii and Botrytis aclada cause this disease in onion and Botrytis porri causes it in garlic. According to the University of California,Initial symptoms usually begin at the neck, where affected tissue softens, becomes water-soaked, and turns brown. In a humid atmosphere, a gray and feltlike growth (where spores are produced) appears on rotting scales, and mycelia may develop between scales. Dark-brown-to-black sclerotia (the resting bodies of the pathogen) may eventually develop in the neck or between scales.Agriculture: Onion and Garlic Pest Management Guidelines: Botrytis Neck and Bulb Rot by the University of California, Agriculture and Natural Resources
Cultivation
Garlic is easy to cultivate and may grow year-round in mild climates. While sexual propagation of garlic is possible, nearly all of the garlic in cultivation is propagated asexually by planting individual cloves in the ground.
In colder climates, cloves are best planted about six weeks before the soil freezes. The goal is to have the bulbs produce only roots and no shoots above the ground."October is garlic planting time", Michigan State University Extension, 2011, https://www.canr.msu.edu/news/october_is_garlic_planting_time Accessed Dec. 2019 Harvest is in late spring or early summer.
Garlic plants can be grown closely together, leaving enough space for the bulbs to mature, and are easily grown in containers of sufficient depth. Garlic does well in loose, dry, well-drained soils in sunny locations, and is hardy throughout USDA climate zones 4–9. When selecting garlic for planting, it is important to pick large bulbs from which to separate cloves. Large cloves, along with proper spacing in the planting bed, will also increase bulb size. Garlic plants prefer to grow in a soil with a high organic material content, but are capable of growing in a wide range of soil conditions and pH levels.
There are different varieties of garlic, most notably split into the subspecies of hardneck garlic and softneck garlic. The latitude where the garlic is grown affects the choice of type, as garlic can be day-length sensitive. Hardneck garlic is generally grown in cooler climates and produces relatively large cloves, whereas softneck garlic is generally grown closer to the equator and produces small, tightly packed cloves.
Garlic scapes are removed to focus all the garlic's energy into bulb growth. The scapes can be eaten raw or cooked.
Propagation The method of propagating garlic from planting cloves is called division. Asexual propagation of garlic for production purposes requires cool temperatures that can vary depending on the cultivar. Hardneck varieties require long cold temperature exposure whereas softneck varieties thrive in milder climates. This cold climate is required for the process of vernalization, a form of stratification of the cloves necessary for the development of multiple-clove bulbs. Solo garlic is the result of garlic grown without the process of vernalization.
Production + Green garlic production 21.6 3.2 0.6 0.5 0.2 World 29.7
In 2024, world production of garlic was 30 million tonnes, with China accounting for 73% of the total (table).
Adverse effects and toxicology The scent of garlic is known to linger upon the human body and cause bad breath (halitosis) and body odor. This is caused by allyl methyl sulfide (AMS). AMS is a volatile liquid which is absorbed into the blood during the metabolism of garlic-derived sulfur compounds; from the blood it travels to the lungs (and from there to the mouth, causing garlic breath) and skin, where it is exuded through skin pores. Since digestion takes several hours, and release of AMS several hours more, the effect of eating garlic may be present for a long time. Washing the skin with soap is only a partial and imperfect solution to the smell. Studies have shown sipping milk at the same time as consuming garlic can significantly neutralize bad breath. Mixing garlic with milk in the mouth before swallowing reduced the odor better than drinking milk afterward. Plain water, mushrooms, and basil may also reduce the odor; the mix of fat and water found in milk, however, was the most effective.
Abundant sulfur compounds in garlic are also responsible for turning garlic green or blue during pickling and cooking. Under these conditions (i.e., acidity, heat) the sulfur-containing compound alliin reacts with common amino acids to make pyrroles, clusters of carbon-nitrogen rings. These rings can be linked together into polypyrrole molecules. Ring structures absorb particular wavelengths of light and thus appear colored. The two-pyrrole molecule looks red, the three-pyrrole molecule looks blue, and the four-pyrrole molecule looks green (like chlorophyll, a tetrapyrrole). Like chlorophyll, the pyrrole pigments are safe to eat. Upon cutting, similar to a color change in onion caused by reactions of amino acids with sulfur compounds, garlic can turn green.