Hemp, or industrial hemp (from Old English hænep), typically found in the northern hemisphere, is a variety of the Cannabis sativa plant species that is grown specifically for the industrial uses of its derived products. It is one of the fastest growing plants and was one of the first plants to be spun into usable fiber 10,000 years ago. It can be refined into a variety of commercial items including paper, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.
Although cannabis as a drug and industrial hemp both derive from the species Cannabis sativa and contain the psychoactive component tetrahydrocannabinol (THC), they are distinct strains with unique phytochemical compositions and uses. Hemp has lower concentrations of THC and higher concentrations of cannabidiol (CBD), which decreases or eliminates its psychoactive effects. The legality of industrial hemp varies widely between countries. Some governments regulate the concentration of THC and permit only hemp that is bred with an especially low THC content.
The etymology is uncertain but there appears to be no common Proto-Indo-European source for the various forms of the word; the Greek term kánnabis is the oldest attested form, which may have been borrowed from an earlier Scythian or Thracian word. Then it appears to have been borrowed into Latin, and separately into Slavic and from there into Baltic, Finnish, and Germanic languages. Following Grimm’s law, the “k” would have changed to “h” with the first Germanic sound shift, after which it may have been adapted into the Old English form, hænep. However, this theory assumes that hemp was not widely spread among different societies until after it was already being used as a psychoactive drug, which Adams and Mallory (1997) believe to be unlikely based on archaeological evidence. Barber (1991) however, argued that the spread of the name “kannabis” was due to its historically more recent drug use, starting from the south, around Iran, whereas non-THC varieties of hemp are older and prehistoric. Another possible source of origin is Assyrian qunnabu, which was the name for a source of oil, fiber, and medicine in the 1st millennium BC.
Cognates of hemp in other Germanic languages include Dutch hennep, Danish and Norwegian hamp, German Hanf, and Swedish hampa.
Hemp is used to make a variety of commercial and industrial products including rope, textiles, clothing, shoes, food, paper, bioplastics, insulation, and biofuel. The bast fibers can be used to make textiles that are 100% hemp, but they are commonly blended with other fibers, such as flax, cotton or silk, as well as virgin and recycled polyester, to make woven fabrics for apparel and furnishings. The inner two fibers of the plant are more woody and typically have industrial applications, such as mulch, animal bedding and litter. When oxidized (often erroneously referred to as “drying”), hemp oil from the seeds becomes solid and can be used in the manufacture of oil-based paints, in creams as a moisturizing agent, for cooking, and in plastics. Hemp seeds have been used in bird feed mix as well. A survey in 2003 showed that more than 95% of hemp seed sold in the European Union was used in animal and bird feed.
Hemp seeds can be eaten raw, ground into hemp meal, sprouted or made into dried sprout powder. The leaves of the hemp plant can be consumed raw in salads. Hemp seeds can also be made into a liquid and used for baking or for beverages such as hemp milk, hemp juice, and tea. Hemp oil is cold-pressed from the seed and is high in unsaturated fatty acids.
In 2011, the U.S. imported $11.5 million worth of hemp products, mostly driven by growth in the demand for hemp seed and hemp oil for use as ingredients in foods such as granola.
In the UK, the Department for Environment, Food and Rural Affairs treats hemp as a purely non-food crop, but with proper licensing and proof of less than 0.2% THC concentration, hemp seeds can be imported for sowing or for sale as a food or food ingredient. In the U.S., imported hemp can be used legally in food products and, as of 2000, was typically sold in health food stores or through mail order.
A 100-gram portion of hulled hemp seeds supplies 586 calories. They contain 5% water, 5% carbohydrates, 49% total fat, and 31% protein. Hemp seeds are notable in providing 64% of the Daily Value (DV) of protein per 100-gram serving. Hemp seeds are a rich source of dietary fiber (20% DV), B vitamins, and the dietary minerals manganese (362% DV), phosphorus (236% DV), magnesium(197% DV), zinc (104% DV), and iron (61% DV). About 73% of the energy in hempseed is in the form of fats and essential fatty acids, mainly polyunsaturated fatty acids, linoleic, oleic, and alpha-linolenic acids.
Hempseed’s amino acid profile is comparable to other sources of protein such as meat, milk, eggs and soy. Protein digestibility-corrected amino acid scores (PDCAAS), which attempt to measure the degree to which a food for humans is a “complete protein”, were 0.49–0.53 for whole hemp seed, 0.46–0.51 for hempseed meal, and 0.63–0.66 for hulled hempseed.
Hemp oil oxidizes and turns rancid within a short period of time if not stored properly; its shelf life is extended when it is stored in a dark airtight container and refrigerated. Both light and heat can degrade hemp oil.
Hemp fiber has been used extensively throughout history, with production climaxing soon after being introduced to the New World. For centuries, items ranging from rope, to fabrics, to industrial materials were made from hemp fiber. Hemp was also commonly used to make sail canvas. The word “canvas” is derived from the word cannabis. Pure hemp has a texture similar to linen. Because of its versatility for use in a variety of products, today hemp is used in a number of consumer goods, including clothing, shoes, accessories, dog collars, and home wares.
Concrete-like blocks made with hemp and lime have been used as an insulating material for construction. Such blocks are not strong enough to be used for structural elements; they must be supported by a brick, wood, or steel frame. However, hemp fibres are extremely strong and durable, and have been shown to be usable as a replacement for wood for many jobs, including creating very durable and breathable homes. The most common use of hemp lime in building is by casting the hemp and lime mix while wet around a timber frame with temporary shuttering, and tamping the mix to form a firm mass; after the removal of the temporary shuttering, the solidified hemp mix is then ready to be plastered with a lime plaster.
The first example of the use of hempcrete was in 1986 in France with the renovation of the Maison de la Turquie in Nogent-sur-Seine by the innovator Charles Rasetti. In the UK hemp lime was first used in 2000 for the construction of two test dwellings in Haverhill. Designed by Modece Architects, who pioneered hemp’s use in UK construction, the hemp houses were monitored in comparison with other standard dwellings by BRE. Completed in 2009, the Renewable House is one of the most technologically advanced made from hemp-based materials. The first US home made of hemp-based materials was completed in August 2010 in Asheville, North Carolina.
A panellized system of hemp-lime panels for use in building construction is currently under test in a European Union-funded research collaboration led by the University of Bath. The panels are being designed to assure high-quality construction, rapid on-site erection, optimal hygrothermal performance from day one, and energy- and resource-efficient buildings. The 36-month-long work programme aims to refine product and manufacturing protocols, produce data for certification and marketing, warranty, insurance cover, and availability of finance. It also includes the development of markets in Britain, France, and Spain.
Hemp is used as an internal plaster and is a mixture of hemp hurd (shive) mixed with larger proportions of a lime-based binder. Hemp plaster has insulative qualities.
A mixture of fiberglass, hemp fiber, kenaf, and flax has been used since 2002 to make composite panels for automobiles. The choice of which bast fiber to use is primarily based on cost and availability. Various car makers are beginning to use hemp in their cars, including Audi, BMW, Ford, GM, Chrysler, Honda, Iveco, Lotus, Mercedes, Mitsubishi, Porsche, Saturn, Volkswagen and Volvo. For example, the Lotus Eco Elise and the Mercedes C-Class both contain hemp (up to 20 kg in each car in the case of the latter).
Hemp paper are paper varieties consisting exclusively or to a large extent from pulp obtained from fibers of industrial hemp. The products are mainly specialty papers such as cigarette paper, banknotes and technical filter papers. Compared to wood pulp, hemp pulp offers a four to five times longer fibre, a significantly lower lignin fraction as well as a higher tear resistance and tensile strength. However, production costs are about four times higher than for paper from wood, so hemp paper could not be used for mass applications as printing, writing and packaging paper.
Hemp jewelry is the product of knotting hemp twine through the practice of macramé. Hemp jewellery includes bracelets, necklaces, anklets, rings, watches and other adornments. Some jewellery features beads made from crystals, glass, stone, wood and bones. The hemp twine varies in thickness and comes in a variety of colors. There are many different stitches used to create hemp jewellery, however, the half knot and full knot stitches are most common.
In recent years, hemp has been growing in popularity as a material used in shoes. Today you can find boots, athletic shoes, sandals, and dress shoes that are made with 100% hemp fiber, or textiles that blend hemp fibers with materials such as cotton, jute, virgin polyester, and recycled polyester. The strength of hemp fibers makes it an ideal material for shoes because it’s durable. In addition, it’s breathable and naturally antimicrobial, so it doesn’t hold on to odors. Because hemp can be grown sustainably, shoes, clothing, and accessories made with hemp are representative of the sustainable fashion movement.
Hemp rope was used in the age of sailing ships, though the rope had to be protected by tarring, since hemp rope has a propensity for breaking from rot, as the capillary effect of the rope-woven fibers tended to hold liquid at the interior, while seeming dry from the outside. Tarring was a labor-intensive process, and earned sailors the nickname “Jack Tar”. Hemp rope was phased out when Manila, which does not require tarring, became widely available. Manila is sometimes referred to as Manila hemp, but is not related to hemp; it is abacá, a species of banana.
Hemp shives are the core of the stem, hemp hurds are broken parts of the core. In the EU, they are used for animal bedding (horses, for instance), or for horticultural mulch. Industrial hemp is much more profitable if both fibers and shives (or even seeds) can be used.
Hemp can be used as a “mop crop” to clear impurities out of wastewater, such as sewage effluent, excessive phosphorus from chicken litter, or other unwanted substances or chemicals. Additionally, hemp is being used to clean contaminants at the Chernobyl nuclear disaster site, by way of a process which is known as phytoremediation—the process of clearing radioisotopes and a variety of other toxins from the soil, water, and air.
Hemp crops are tall, have thick foliage, and can be planted densely, and thus can be grown as a smother crop to kill tough weeds. Using hemp this way can help farmers avoid the use of herbicides, gain organic certification, and gain the benefits of crop rotation. However, due to the plant’s rapid and dense growth characteristics, some jurisdictions consider hemp a prohibited and noxious weed, much like Scotch Broom.
Biodiesel can be made from the oils in hemp seeds and stalks; this product is sometimes called “hempoline”. Alcohol fuel (ethanol or, less commonly, methanol) can be made by fermenting the whole plant.
Filtered hemp oil can be used directly to power diesel engines. In 1892, Rudolf Diesel invented the diesel engine, which he intended to power “by a variety of fuels, especially vegetable and seed oils, which earlier were used for oil lamps, i.e. the Argand lamp.”
Production of vehicle fuel from hemp is very small. Commercial biodiesel and biogas is typically produced from cereals, coconuts, palmseeds and cheaper raw materials like garbage, wastewater, dead plant and animal material, animal feces and kitchen waste.
Traditionally, hemp stalks would be water-retted first before the fibers were beaten off the inner hurd by hand, a process known as scutching. As mechanical technology evolved, separating the fiber from the core was accomplished by crushing rollers and brush rollers that would produce a nearly clean fiber. After the Marijuana Tax Act was implemented in 1938, the technology for separating the fibers from the core remained “frozen in time”.
Only in 1997, did Ireland, parts of the Commonwealth and other countries begin to legally grow industrial hemp again. Iterations of the 1930s decorticator have been met with limited success, along with steam explosion and chemical processing known as thermomechanical pulping.
Hemp is usually planted between March and May in the northern hemisphere, between September and November in the southern hemisphere. It matures in about three to four months.
Millennia of selective breeding have resulted in varieties that display a wide range of traits; e.g. suited for a particular environments/latitudes, producing different ratios and compositions of terpenoids and cannabinoids (CBD, THC, CBG, CBC, CBN…etc.), fibre quality, oil/seed yield etc. Hemp grown for fiber is planted closely, resulting in tall, slender plants with long fibers.
Use of industrial hemp plant and its cultivation was commonplace until the 1900s, when it was associated with its genetic sibling aka Drug-Type Cannabis species (which contain higher levels of psychoactive THC). Influential groups misconstrued hemp as a dangerous ‘drug’, even though it is not a ‘drug’ and it has the potential to be a sustainable & profitable alternative crop.
In the United States, the public’s perception of hemp as marijuana has blocked hemp from becoming a useful crop and product,” in spite of its vital importance prior to World War II. Ideally, according to Britain’s Department for Environment, Food and Rural Affairs, the herb should be desiccated and harvested towards the end of flowering. This early cropping reduces the seed yield but improves the fiber yield and quality. In these strains of industrial hemp* the tetrahydrocannabinol (THC) content would have been very low.
The seeds are sown from mid-April to mid-May with grain drills to 4–6 cm sowing depth. Hemp needs less fertilizer than corn does. A total of 60–150 kg of nitrogen, 40–140 kg phosphorus (P2O5) and 75–200 kg of potassium  per acre for hemp fiber made before sowing and again later, maybe three to four weeks. When practiced, especially in France double use of fiber and seed fertilization with nitrogen doses up to 100 kg / ha rather low. Organic fertilizers such as manure can utilize industrial hemp well. Neither weeds nor crop protection measures are necessary.
In contrast to cannabis for medical use, varieties grown for fiber and seed have less than 0.3% THC and are unsuitable for producing hashish and marijuana. Present in industrial hemp, cannabidiol is a major constituent among some 560 compounds found in hemp.
Cannabis sativa L. subsp. sativa var. sativa is the variety grown for industrial use, while C. sativa subsp. indica generally has poor fiber quality and female buds from this variety are primarily used for recreational and medicinal purposes. The major differences between the two types of plants are the appearance, and the amount of Δ9-tetrahydrocannabinol (THC) secreted in a resinous mixture by epidermal hairs called glandular trichomes, although they can also be distinguished genetically. Oilseed and fiber varieties of Cannabisapproved for industrial hemp production produce only minute amounts of this psychoactive drug, not enough for any physical or psychological effects. Typically, hemp contains below 0.3% THC, while cultivars of Cannabis grown for medicinal or recreational use can contain anywhere from 2% to over 20%.
Smallholder plots are usually harvested by hand. The plants are cut at 2 to 3 cm above the soil and left on the ground to dry. Mechanical harvesting is now common, using specially adapted cutter-binders or simpler cutters.
The cut hemp is laid in swathes to dry for up to four days. This was traditionally followed by retting, either water retting (the bundled hemp floats in water) or dew retting (the hemp remains on the ground and is affected by the moisture in dew, and by molds and bacterial action).
For profitable hemp farming, particularly deep, humus-rich, nutrient-rich soil with controlled water flow is preferable. Waterlogged acidic, compressed or extremely light (sandy) soils primarily affect the early development of plants. Steep and high altitudes of more than 400 m above sea level are best avoided. Hemp is relatively insensitive to cold temperatures and can withstand frost down to −5 °C. Seeds can germinate down to 1–3 °C. Hemp needs a lot of heat, so earlier varieties come to maturation. The water requirement is 300–500 l/kg dry matter. This is around 1/14th that of cotton, which takes between 7,000 and 29,000 l/kg, according to WWF. Roots can grow up to 3 feet into the soil and use water from deeper soil layers.
Hemp benefits crops grown after it. So, it is generally grown before winter cereals. Advantageous changes are high weed suppression, soil loosening by the large hemp root system, and the positive effect on soil tilth. Since hemp is very self-compatible, it can also be grown several years in a row in the same fields (monoculture).
Hemp plants can be vulnerable to various pathogens, including bacteria, fungi, nematodes, viruses and other miscellaneous pathogens. Such diseases often lead to reduced fiber quality, stunted growth, and death of the plant. These diseases rarely affect the yield of a hemp field, so hemp production is not traditionally dependent on the use of pesticides.
Hemp is considered by a 1998 study in Environmental Economics to be environmentally friendly due to a decrease of land use and other environmental impacts, indicating a possible decrease of ecological footprint in a US context compared to typical benchmarks. A 2010 study, however, that compared the production of paper specifically from hemp and eucalyptus concluded that “industrial hemp presents higher environmental impacts than eucalyptus paper”; however, the article also highlights that “there is scope for improving industrial hemp paper production”. Hemp is also claimed to require few pesticides and no herbicides, and it has been called a carbon negative raw material. Results indicate that high yield of hemp may require high total nutrient levels (field plus fertilizer nutrients) similar to a high yielding wheat crop.
The world-leading producer of hemp is China, which produces more than 70% of the world output. France ranks second with about a quarter of the world production. Smaller production occurs in the rest of Europe, Chile, and North Korea. Over 30 countries produce industrial hemp, including Australia, Austria, Canada, Chile, China, Denmark, Egypt, Finland, Great Britain, Germany, Greece, Hungary, India, Italy, Japan, Korea, Netherlands, New Zealand, Poland, Portugal, Romania, Russia, Slovenia, Spain, Sweden, Switzerland, Thailand, Turkey and Ukraine.
The United Kingdom and Germany resumed commercial production in the 1990s. British production is mostly used as bedding for horses; other uses are under development. Companies in Canada, the UK, the United States, and Germany, among many others, process hemp seed into a growing range of food products and cosmetics; many traditional growing countries still continue to produce textile-grade fibre.
Air-dried stem yields in Ontario have from 1998 and onward ranged from 2.6-14.0 tonnes of dry, retted stalks per hectare (1-5.5 t/ac) at 12% moisture. Yields in Kent County, have averaged 8.75 t/ha (3.5 t/ac). Northern Ontario crops averaged 6.1 t/ha (2.5 t/ac) in 1998. Statistic for the European Union for 2008 to 2010 say that the average yield of hemp straw has varied between 6.3 and 7.3 ton per ha. Only a part of that is bast fiber. Around one tonne of bast fiber and 2-3 tonnes of core material can be decorticated from 3-4 tonnes of good-quality, dry-retted straw. For an annual yield of this level is it in Ontario recommended to add nitrogen (N):70–110 kg/ha, phosphate (P2O5): up to 80 kg/ha and potash (K2O): 40–90 kg/ha. The average yield of dry hemp stalks in Europe was 6 ton/ha (2.4 ton/ac) in 2001 and 2002.
FAO argue that an optimum yield of hemp fiber is more than 2 tonnes per ha, while average yields are around 650 kg/ha.
From the 1950s to the 1980s, the Soviet Union was the world’s largest producer of hemp (3,000 km2 in 1970). The main production areas were in Ukraine, the Kursk and Orel regions of Russia, and near the Polish border. Since its inception in 1931, the Hemp Breeding Department at the Institute of Bast Crops in Hlukhiv (Glukhov), Ukraine, has been one of the world’s largest centers for developing new hemp varieties, focusing on improving fiber quality, per-hectare yields, and low THC content.
After the collapse of the Soviet Union, the commercial cultivation of hemp declined sharply. However, at least an estimated 2.5 million acres of hemp grow wild in the Russian Far East and Black Sea regions.
Hemp is possibly one of the earliest plants to be cultivated. An archeological site in the Oki Islands near Japan contained cannabis achenes from about 8000 BC, probably signifying use of the plant. Hemp use archaeologically dates back to the Neolithic Age in China, with hemp fiber imprints found on Yangshao culture pottery dating from the 5th millennium BC. The Chinese later used hemp to make clothes, shoes, ropes, and an early form of paper. The classical Greek historian Herodotus (ca. 480 BC) reported that the inhabitants of Scythia would often inhale the vapors of hemp-seed smoke, both as ritual and for their own pleasurable recreation.
Textile expert Elizabeth Wayland Barber summarizes the historical evidence that Cannabis sativa, “grew and was known in the Neolithic period all across the northern latitudes, from Europe (Germany, Switzerland, Austria, Romania, Ukraine) to East Asia (Tibet and China),” but, “textile use of Cannabis sativa does not surface for certain in the West until relatively late, namely the Iron Age.” “I strongly suspect, however, that what catapulted hemp to sudden fame and fortune as a cultigen and caused it to spread rapidly westwards in the first millennium B.C. was the spread of the habit of pot-smoking from somewhere in south-central Asia, where the drug-bearing variety of the plant originally occurred. The linguistic evidence strongly supports this theory, both as to time and direction of spread and as to cause.”
Jews living in Palestine in the 2nd century were familiar with the cultivation of hemp, as witnessed by a reference to it in the Mishna (Kil’ayim 2:5) as a variety of plant, along with Arum, that sometimes takes as many as three years to grow from a seedling. In late medieval Germany and Italy, hemp was employed in cooked dishes, as filling in pies and tortes, or boiled in a soup. Hemp in later Europe was mainly cultivated for its fibers, and was used for ropes on many ships, including those of Christopher Columbus. The use of hemp as a cloth was centered largely in the countryside, with higher quality textiles being available in the towns.
The Spaniards brought hemp to the Americas and cultivated it in Chile starting about 1545. Similar attempts were made in Peru, Colombia, and Mexico, but only in Chile did the crop find success. In July 1605, Samuel Champlain reported the use of grass and hemp clothing by the (Wampanoag) people of Cape Cod and the (Nauset) people of Plymouth Bay told him they harvested hemp in their region where it grew wild to a height of 4 to 5 ft. In May 1607, “hempe” was among the crops Gabriel Archer observed being cultivated by the natives at the main Powhatan village, where Richmond, Virginia is now situated; and in 1613, Samuell Argall reported wild hemp “better than that in England” growing along the shores of the upper Potomac. As early as 1619, the first Virginia House of Burgesses passed an Act requiring all planters in Virginia to sow “both English and Indian” hemp on their plantations. The Puritans are first known to have cultivated hemp in New England in 1645.
George Washington pushed for the growth of hemp and even grew hemp himself, as it was a cash crop commonly used to make rope and fabric. In May 1765 he noted in his diary about the sowing of seeds each day until mid-April. Then he recounts the harvest in October which he grew 27 bushels that year.
There is some speculation that George Washington smoked the flower of the cannabis plant in order to achieve a recreational high (“Like all farmers, Washington probably sampled the quality and potency of what he grew, and he may have used this hemp to treat his chronic tooth aches”), but there is no evidence in any of his writings that he grew hemp for anything other than industrial purposes. It is sometimes supposed that an excerpt from Washington’s diary, which reads “Began to seperate [sic] the Male from the Female hemp at Do.&—rather too late” is evidence that he was trying to grow female plants for the THC found in the flowers. However, the editorial remark accompanying the diary states that “This may arise from their [the male] being coarser, and the stalks larger” In subsequent days, he describes soaking the hemp (to make the fibers usable) and harvesting the seeds, suggesting that he was growing hemp for industrial purposes, not recreational.
George Washington also imported the Indian Hemp plant from Asia, which was used for fiber and, by some growers, for intoxicating resin production. In a letter to William Pearce who managed the plants for him Washington says, “What was done with the Indian Hemp plant from last summer? It ought, all of it, to be sown again; that not only a stock of seed sufficient for my own purposes might have been raised, but to have disseminated seed to others; as it is more valuable than common hemp.”
Additional presidents known to have farmed hemp include Thomas Jefferson, James Madison, James Monroe, Andrew Jackson, Zachary Taylor, and Franklin Pierce.
Historically, hemp production had made up a significant portion of antebellum Kentucky’s economy. Before the American Civil War, many slaves worked on plantations producing hemp.
In 1937, the Marihuana Tax Act of 1937 was passed in the United States, levying a tax on anyone who dealt commercially in cannabis, hemp, or marijuana. The passing of the Act to destroy the US hemp industry has been disputed to involve businessmen Andrew Mellon, Randolph Hearst and the Du Pont family.
One claim is that Hearst believed that his extensive timber holdings were threatened by the invention of the decorticator which he feared would allow hemp to become a cheap substitute for the paper pulp used for newspaper. Historical research indicates this fear was unfounded because improvements of the decorticators in the 1930s – machines that separated the fibers from the hemp stem – could not make hemp fiber a cheaper substitute for fibers from other sources. Further, decorticators did not perform satisfactorily in commercial production.
Another claim is that Mellon, Secretary of the Treasury and the wealthiest man in America at that time, had invested heavily in DuPont’s new synthetic fiber, nylon, and believed that the replacement of the traditional resource, hemp, was integral to the new product’s success. The company DuPont and many industrial historians dispute a link between nylon and hemp, nylon became immediately a scarce commodity. Nylon had characteristics that could be used for toothbrushes (sold from 1938) and very thin nylon fiber could compete with silk and rayon in various textiles normally not produced from hemp fiber, such as very thin stockings for women.
Hemp was used extensively by the United States during World War II to make uniforms, canvas, and rope. Much of the hemp used was cultivated in Kentucky and the Midwest. During World War II, the U.S. produced a short 1942 film, Hemp for Victory, promoting hemp as a necessary crop to win the war.