Hemp

• 1. Introduction

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  People were already spinning hemp into usable fiber 50,000 years ago, which makes it one of the first plants ever turned into thread. Alongside bamboo, it also ranks among the fastest growing plants on Earth. Hemp is a group of Cannabis sativa cultivars grown for industrial and consumable use. From it come paper, rope, textiles, clothing, paint, insulation, biofuel, food and animal feed. Even biodegradable plastics can be made from it. Yet the rules governing the plant vary widely from one country to the next, and some governments allow only especially low-THC varieties into commercial production. Why does a plant this useful carry a name that no one can trace with certainty? How did a crop that rigged ships and clothed armies disappear from so many fields? And what does it take to bring it back?

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• 2. A Word With Uncertain Roots

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  The oldest attested form of the word is the Greek kánnabis, written κάνναβις, and even that may have been borrowed from an earlier Scythian or Thracian term. From Greek it appears to have passed into Latin. Separately it entered the Slavic languages, and from there it reached the Baltic, Finnish and Germanic tongues. No common Proto-Indo-European source seems to lie behind these forms.

  Germanic languages explain the English name. Under Grimm's law, the first Germanic sound shift turned the k into an h, producing the Proto-Germanic form hanapiz. That developed into the Old English hænep, also written henep.

  The textile scholar Barber argued in 1991 that the name kannabis spread with a more recent use of the plant, beginning in the south around Iran. Non-THC hemp, in her view, is far older and prehistoric. Another candidate for the source is the Assyrian qunnabu, a name used in the 1st millennium BC for a source of oil, fiber and medicine.

  The cousins of the English word are easy to hear. Dutch has hennep, German has Hanf, Swedish has hampa, and Icelandic has hampur. Danish and Norwegian use hamp, and Saterland Frisian says Hoamp. In all of these languages, a single word can mean either the industrial fiber plant or narcotic strains, a blur that would matter enormously once lawmakers got involved.

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• 3. Ancient Fiber, Sailing Rope

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  Cannabis achenes, the dry one-seeded fruits of the plant, were found at an archaeological site in the Oki Islands of Japan and date to about 8000 BC. They probably signal that people were already using it. In China, fiber imprints on Yangshao culture pottery from the 5th millennium BC show the same story. The Chinese later made clothes, shoes, ropes and an early form of paper from hemp. Japan's Jōmon period, which ran from 10,000 to 300 BC, left evidence of hemp clothing and of seeds eaten as food.

  Herodotus, writing around 480 BC, reported that the people of Scythia inhaled the vapors of burning hemp seed. They did so as a ritual and also for pleasure.

  The textile expert Elizabeth Wayland Barber gathered the evidence for how the plant spread. She found it known across the northern latitudes in the Neolithic period, from Germany, Switzerland, Austria, Romania and Ukraine to Tibet and China. Yet she noted that textile use does not surface for certain in the West until the Iron Age. She suspected that what sent the plant westward in the first millennium BC was "the habit of pot-smoking" spreading out of south-central Asia.

  One of the earliest known examples of hemp rope and textiles comes from Egypt in 1500 BC. In the 2nd century, Jews living in Palestine knew the plant well enough that the Mishna mentions its cultivation. In the late medieval Holy Roman Empire and in Italy, cooks used hemp seed as a filling for pies and tortes, or boiled it in soup. Later Europe grew it mainly for fiber, and the ropes of many ships, including those of Christopher Columbus, were made from it. Cloth made from hemp was centered in the countryside, while towns could buy finer textiles.

  Hemp also dressed the ships. Sail canvas was commonly made from it, and the English word canvas is derived from cannabis. Pure hemp has a texture much like linen. Rope was a problem at sea, though. Capillary action trapped liquid inside the woven fibers while the outside looked dry, so the rope tended to rot from within. Sailors tarred it to protect it, a labor-intensive job that earned them the nickname Jack Tar. Eventually the lighter manila rope replaced it. Manila is sometimes called Manila hemp, but it is actually abacá, a species of banana.

  Portuguese lands began cultivating hemp around the fourteenth century, for rope and plugs for their ships. After the Restoration of Independence in 1640, King John IV tried to rebuild a failing fleet by pushing hemp growing harder. He ordered a Royal Linen and Hemp Factory built in the town of Torre de Moncorvo. Portugal also drew on its colonies for supply, including parts of Brazil.

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• 4. Hemp In Early America

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  The Spaniards began cultivating hemp in Chile around 1545. They tried the same in Peru, Colombia and Mexico, but only in Chile did the crop succeed.

  Farther north, the explorer Samuel Champlain wrote in July 1605 about hemp and grass clothing worn by the Wampanoag people of Cape Cod. The Nauset people of Plymouth Bay told him they harvested hemp where it grew wild, reaching 4 to 5 feet in height. In May 1607, Gabriel Archer saw "hempe" among the crops at the main Powhatan village, on the site of present-day Richmond, Virginia. In 1613, Samuell Argall reported wild hemp "better than that in England" along the upper Potomac.

  Settlers soon wrote hemp into law. As early as 1619, the first Virginia House of Burgesses passed an Act requiring every planter in Virginia to sow "both English and Indian" hemp. The Puritans are first known to have grown it in New England in 1645.

  George Washington pushed hard for the crop, since it was a cash crop used for rope and fabric. His diary from May 1765 records sowing seeds, and the October harvest that year came to 27 bushels. One diary line about separating male from female plants is sometimes read as proof that he wanted the female plants for their THC. The editorial remark that goes with it offers a different explanation, that the male plants were coarser and had larger stalks. Entries on the following days describe soaking the hemp to free its fibers and harvesting seeds, which points to industrial purposes.

  Washington also imported Indian hemp from Asia, used for fiber and by some growers for an intoxicating resin. In a 1796 letter to William Pearce, who managed the plants for him, he asked what had become of it. He wrote that it "ought, all of it, to be sown again", and that it was "more valuable than common hemp."

  Other presidents known to have farmed hemp include Thomas Jefferson, James Madison, James Monroe, Andrew Jackson, Zachary Taylor and Franklin Pierce. Hemp made up a significant portion of the economy of antebellum Kentucky, and before the American Civil War, many enslaved people worked on the plantations that produced it.

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• 5. Prohibition And War

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  The line between hemp and its drug-bearing relatives comes down to a number. Hemp typically contains below 0.3% THC, while cannabis grown for medicinal or recreational use can contain anywhere from 2% to over 20%. Even so, through the early 1900s hemp was tied in the public mind to its genetic sibling, and influential groups misconstrued it as a dangerous drug.

  The Marihuana Tax Act of 1937 placed a tax on anyone dealing commercially in cannabis, hemp or marijuana. It has long been reputed that the businessmen Andrew Mellon and Randolph Hearst, along with the Du Pont family, helped pass it to destroy the hemp industry. One claim says Hearst feared that the decorticator, a machine that separates fiber from the stem, would make hemp a cheap rival to the pulp behind his newspapers and timber holdings. Historical research finds the fear unfounded, since 1930s decorticators could not make hemp fiber cheaper and performed poorly in commercial production.

  A second claim says Mellon, the Treasury Secretary and the wealthiest man in America, had invested heavily in DuPont's new synthetic fiber, nylon. He supposedly believed that hemp had to be replaced for nylon to succeed. DuPont and many industrial historians dispute any link. Nylon did sell, from toothbrushes in 1938 to very thin stockings that competed with silk and rayon, goods not normally made from hemp.

  Whatever the motives, fiber technology stalled. After the Act took effect, the methods for separating fiber from the core remained "frozen in time."

  Then came the Second World War. Before it, the United States Navy bought jute and Manila hemp for ship cordage from the Philippines and Indonesia. Japan cut off those supply lines, and America turned inward and revived hemp farming on its own soil. The Department of Agriculture lifted the tax on hemp cultivation. In 1942 the government produced a short film, Hemp for Victory, urging farmers to grow it. Farmers raised the harvested area to 36,000 acres, more than 20 times the level of 1941. Much of it grew in Kentucky and the Midwest, and the hemp became uniforms, canvas and rope.

  By the 1980s the film was largely forgotten, and the government even denied it existed. The activist Jack Herer brought it back to light in his book The Emperor Wears No Clothes.

  Elsewhere, the decline came from the market. In Western Europe, hemp was not legally banned in the 1930s, but commercial growing had already ended as artificial fibers became popular. World fiber production fell from over 300,000 metric tons in 1961 to about 75,000 in the early 1990s, and it has held at that level since.

  Japan took a different road. After the United States restricted marijuana as a narcotic there in 1948, Japan wrote some of the world's strictest laws against it, allowing five years in prison for possession. Those laws exempted hemp growers, whose crop makes robes for Buddhist monks and loincloths for sumo wrestlers.

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• 6. Return To The Fields

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  Ireland and parts of the Commonwealth were among the first to start legally growing industrial hemp again, and they did so only in the 1990s. The United Kingdom and Germany resumed commercial production in the same decade. British hemp is mostly sold as bedding for horses, and growers there need a Home Office licence under the Misuse of Drugs Act 1971. Portugal had made hemp growing illegal in 1971, but European Union regulations later revoked that law for some certified seed varieties.

  Canada's story began at the University of Manitoba in the early 1990s. The Hemp Awareness Committee there worked with the provincial government for research support and won test plot permits. Their efforts led to legalization and the first harvest in 1998, with Health Canada issuing the licences. By 2017, Saskatchewan had more than 56,000 acres in hemp, Alberta had 45,000 and Manitoba had 30,000. Most Canadian hemp feeds the food market, as hulled seeds, oils and protein powders, with only a small fraction going to fiber.

  Australia moved state by state. Tasmania pioneered licensing in the early 1990s, and Victoria followed in 1998. Queensland has allowed licensed industrial production since 2002, and Western Australia passed its Industrial Hemp Act in 2004. New South Wales issued licences under the Hemp Industry Regulations Act 2008, effective the 6th of November 2008. South Australia was most recent, with its Industrial Hemp Act commencing on the 12th of November 2017.

  The United States opened up more slowly. Oregon began approving industrial hemp licences in 2009. In 2013, after the legalization of marijuana, farmers in Colorado planted and harvested the first hemp crop the country had seen in over half a century. The Agricultural Act of 2014 then created a Hemp Farming Pilot Program, which let universities and state agriculture departments grow hemp without the consent of the Drug Enforcement Administration. Kentucky, formerly the leading producer, resumed in 2014, and North Carolina and Washington State followed in 2017. By the end of 2017, at least 34 states had industrial hemp programs. In 2018, New York began its own research pilots, including ones at Cornell University, Binghamton University and SUNY Morrisville.

  The 2018 Farm Bill, which incorporated the Hemp Farming Act of 2018, removed hemp from Schedule I and made it an agricultural commodity. Farmers could now get production licences, loans and federal crop insurance. By October 2019, hemp was legal to grow in 46 states under federal law. The industry estimated its sales at around $820 million a year as of 2017, with hemp-derived CBD driving the growth. Yet businesses still struggled. A Forbes case study found that most online advertising platforms and financial institutions do not distinguish between hemp and marijuana.

  The global picture looks different. China produces more than 70% of the world's hemp, and France ranks second with about a quarter, from 8000 hectares. More than 30 countries grow industrial hemp. The Soviet Union was the largest producer from the 1950s to the 1980s, with 3000 square kilometers in 1970. The Hemp Breeding Department at the Institute of Bast Crops in Hlukhiv, Ukraine, founded in 1931, became one of the world's largest centers for developing new varieties. After the Soviet collapse, cultivation fell sharply, but an estimated 2.5 million acres of hemp still grow wild in the Russian Far East and the Black Sea regions.

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• 7. Seeds, Oil, And Fuel

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  A 100 gram portion of hulled hemp seeds supplies 533 calories. By weight, the seeds are 5% water, 5% carbohydrates, 49% fat and 32% protein, and they are a rich source of several B vitamins and dietary minerals. People eat them raw, ground into meal, sprouted, or dried into sprout powder. A seed slurry goes into baking and into drinks such as hemp milk and tisanes. The oil is cold-pressed from the seed and is high in unsaturated fatty acids.

  Three proteins dominate the seed. Edestin makes up 83% of the total, albumin 13%, and beta-conglycinin up to 5%. Untreated hemp protein is highly digestible compared with soy protein, and its amino acid profile is comparable to meat, milk, eggs and soy. The most abundant amino acid is glutamic acid, followed by arginine. Still, its essential amino acids rank below those of soy or casein. The seeds also contain phytic acid, trypsin inhibitors and tannins, which interfere with nutrition. Protein is concentrated in the inner layer of the seed, so dehulling raises the protein share, as does using the press cake left after the oil is expelled.

  The oil has a weakness. It turns rancid within a short time if stored badly, and both light and heat degrade it. A dark, airtight container in the refrigerator extends its life. The same press cake, called hemp seed meal, is increasingly tested as feed for poultry, swine, cattle, fish and pets.

  Rules for eating hemp differ by country. In the United Kingdom, the Department for Environment, Food and Rural Affairs treats hemp as a non-food crop. With proper licensing and proof of low THC, however, seeds can be imported for sowing or sale as food.

  Hemp can run engines as well. Biodiesel, sometimes called hempoline, can be made from the oils in seeds and stalks. Fermenting the whole plant yields ethanol or, less commonly, methanol. Filtered hemp oil can power diesel engines directly, which echoes the ideas of Rudolf Diesel. In 1892 he invented the engine meant to run on "a variety of fuels, especially vegetable and seed oils." In practice, hemp fuel production is very small, because cereals, coconuts, palm seeds and waste materials are cheaper raw materials.

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• 8. Hempcrete And Beyond

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  At the end of the twentieth century, Charles Rasetti renovated the Maison de la Turquie in Nogent-sur-Seine, France. He is credited with first inventing and applying hempcrete in construction there. In the 2000s, Modece Architects used hemp-lime for test designs in Haverhill, and the Building Research Establishment monitored the dwellings against other buildings. The Renewable House was completed in 2009 and counted among the most technologically advanced hemp-based structures. A year later, the first home made of hemp-based materials was finished in Asheville, North Carolina.

  Hempcrete is a blend of hemp hurds, hydraulic lime and water. It is roughly seven times lighter than common concrete, and it cannot carry structural loads, so it is used as infill around a timber frame. Builders cast the wet mix around the frame behind temporary shuttering, tamp it, and plaster it with lime after it hardens. The hardening is a mineralization called carbonation, in which silica in the shives reacts with lime. It keeps absorbing CO2 as it cures.

  Hemp insulation is flexible, lightweight and non-toxic, and it can be cut to fit during installation. It absorbs roughly double the heat of mineral insulation and also dampens airborne sound. In 2022, the International Code Council accepted hemp-lime, and the 2024 International Residential Code carries it as Appendix BL. The cost is the catch. The final report on the Haverhill hemp houses concluded that hemp construction exceeds the cost of traditional materials by £48 per square meter. The University of Bath is researching hemp-lime panel systems, funded by the European Union, with a focus on Britain, France and Spain.

  Cars use the fiber too. Since 2002, a mixture of fiberglass, hemp, kenaf and flax has gone into composite panels for automobiles. The Mercedes C-Class contains up to 20 kilograms of hemp, and the Lotus Eco Elise uses it as well.

  Paper is where hemp has stumbled. Its pulp has fibers four to five times longer than wood pulp and greater tear resistance. It can be whitened with hydrogen peroxide and recycled up to 8 times, against 3 for wood paper. A hemp crop matures in about 3-4 months, while trees can take between 20 and 80 years. But machines that cheaply separate the useful outer fibers from the rest have never fully worked, so hemp paper costs about four times more. A 2010 study even found that hemp paper carried higher environmental impacts than eucalyptus paper, though it saw room for improvement.

  The plant also cleans. Farmers can use it as a "mop crop" to draw phosphorus and other pollutants out of wastewater. At the Chernobyl site, hemp is used for phytoremediation, clearing radioisotopes and other toxins from the soil. A United Nations report notes that hemp uses a quarter of the water that cotton needs. It grows so densely that it smothers tough weeds, though some jurisdictions treat it as a prohibited noxious weed, much like Scotch Broom.

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