Hemp was best cultivated on ground that was suitable for corn in a manner similar to small grains, according to a 1919 report from International Harvester's North Dakota research farm near Grand Forks. Farmers who planted hemp at a rate of three pecks of seed per acre noted that the stand choked out persistent weeds. Agronomists concluded that even if there was no value to the fiber or seed, hemp could effectively be grown in rotation for weed control alone.
Colonial hemp cultivators used rudimentary soil preparation hand tools such as digging sticks, hoes, rakes and spades to loosen the soil. Hemp seed was hand-broadcast, sometimes followed by a light raking. The persistence and scope of ditch weed throughout the U.S. attest to hemp's ability to take care of itself.
Hemp growers took full advantage of improved cultivation practices. Horse-drawn plows, harrows, cultivators and even cultipackers all played a role in hemp production, as with small grains in particular. Planting with horse- or tractor-drawn seed drills later improved stand uniformity, density and contributed greatly to seed economy.
'We drilled hemp with about 6-inch spacing in the late 1930s for a good stand,' Junior Prange explains. 'You got the best fiber on good ground, with close spacing.' Junior recalls that by then the recommended sowing rate was a bushel and a peck of seed per acre.
'Hemp is ready to cut at about 100 days depending on conditions,' Junior says. 'We planted small grain around the hemp so that we could get into the field with the reaper without knocking down any (hemp) stalks.'
Early hemp harvesting methods included cutting the plants with sickles and later hemp knives - backbreaking work often carried out by slaves, sharecroppers or migrant laborers. The hemp knife, longer-handled than the sickle, looked something like a modern corn knife. In some instances, the plants were uprooted rather than cut, but in either case, they were then laid on the ground in thin layers to allow exposure to dew and rain, partially rotting the stems in a process called 'retting.'
Farmers later adapted horse-drawn grain-harvesting tools such as the self-rake reaper to cut hemp stalks. Once cut, the stalks were spread out by hand for retting. Hemp growers also modified horse-drawn sickle-bar mowers by mounting a horizontal bar several feet above the cutter, causing stalks to fall forward as they were cut. The downside of using the modified mower was that the stalks continuously overlapped one another as they fell, making it quite difficult to spread them for retting.
Some innovative farmers modified their reapers for hemp cutting by mounting a reel several feet above the cutter. The purpose of the reel was to lay the hemp stalks evenly on the reaper's table, where they were gathered and evenly swept to the ground. Larger and more successful producers eventually opted for more specialized equipment, available (at least experimentally) in the 1920s from International Harvester. These machines, based on the modified 'high-reel' reapers, were designed to cut the hemp and lay it out evenly.
'My father-in-law, Alfred Loomans, owned a hemp reaper with his brother-in-law, Clarence Bruins,' Harold Rens recalls. 'It was bull-wheel powered and they pulled it with seven horses.' Machines such as those, either horse- or tractor-drawn, were key to convincing modern farmers to embrace hemp as a viable crop. 'The machine had about an 8-foot cutter, which was perfect for hemp that was up to 9 feet tall,' Junior says, explaining that the reel drew the hemp into the cutter and, once cut, onto a canvas conveyor. The conveyor delivered batches of cut stalks to a rotating table that dropped thin layers of stalks with their butt ends aligned on the ground. The end result was an even windrow with the stalks oriented perpendicular to the direction the cutter was traveling, which set the stage for retting.
Before the valuable fibers can be removed efficiently from the hemp stalks, the glue that holds them together must first be loosened (or removed altogether) by retting. Usually, the stalks were dew-retted by allowing them to lie in the field after cutting, although in some areas of the world, hemp was water-retted by placing bundles of stalks in ponds or streams.
The water-retting process yielded more uniform fiber with a direct cost of even more labor. Workers would cut and bundle the hemp, move it to the water, remove it from the water, spread it out to dry, and then pick it up again for further processing. The U.S. Navy paid a premium for water-retted hemp in the early 1800s, but farmers found that the work was so hard that it was simply not worth it. Moreover, that process polluted the water and stripped valuable nutrients from the soil - concerns that even early growers were aware of.
Dew-retting took anywhere from two to six weeks or more, requiring that the hemp stalks be turned at least once for the highest-quality fiber. 'At first, we turned the hemp by hand with a long stick that was slipped under one end and lifted,' Harold explains. It wasn't until the late 1930s that hemp-turning implements became prevalent, at least in the upper Midwest. By 1943, the Tower Co. of Mendota, 111., offered a dedicated tractor-pulled, PTO-driven hemp-turning machine, which helped improve the quality of the fiber.
Once retted, the hemp stalks were bundled, shocked, stacked or hauled to the fiber mill. Shortly after World War I, wheel-driven hemp gatherer-bundler machines were available from International Harvester. 'The gatherer-bundler would pick up the stalks and tie them in a bundle,' Harold says. 'I used to ride on a stone boat pulled behind (the gatherer-bundler) and tip the bundles behind the tractor.' Later McCormick-Deering gatherer-bundlers (still in use into the 1950s) dropped the bundled hemp out of the way automatically.
The bundles of hemp stalks were next shocked to dry until the fiber was extracted, although often after a period of drying, the shocks were collected and the bundles assembled into large stacks designed to protect fiber from further weathering, much like haystacks.
The Matt Rens Co. was well-known for its 50/50 deal with contract growers. The farmers provided the land and growing expenses, and the company provided the specialized machinery, labor and milling. 'It was not unusual for us to make $100 per acre,' Junior says. 'That was quite a bit of money in the Depression.'
Although hemp-processing mills were in existence in the mid-1750s, much of the hemp fiber produced in this country was still processed by hand until the early 1900s. Taking the dry but fully-retted stalks to useable fiber requires three steps: braking, scutching and hackling. The first involves mild crushing or bending of the stalk, which loosens non-fibrous material from the fibers. The second involves scraping the non-fibrous material from the fiber, and the third involves combing the fiber to further clean it and separate long and short fibers.
Primitive hemp brakes continued to be used as long as cheap labor was plentiful. These devices consist of two or more wooden beams fixed to a frame with a set of hinged beams fitted between them. A handful of hemp stalks was placed across the fixed beams and the operator raised and lowered the hinged beams while pulling the bundle of stalks across the fixed beams.
Engine-powered braking mills typically used a stone or rollers to crush the stalks. An early successful hemp mill in Pennsylvania employed a cone-shaped stone rolling on a circular table to crush stalks. Later designs generally used intermeshing fluted rollers much like conditioning rollers on a modern mower-conditioner.
Primitive scutching tools included wooden 'knives' or 'paddles' with V-shaped notches through which crushed stalks were drawn to remove non-fibrous parts of the stem loosened by braking. Mechanized scutching tools were generally built into the mechanical brake by adding specially-shaped rollers whose flutes scraped the stalks rather than crushing them.
Primitive hackling tools essentially consisted of a board through which a number of iron spikes had been driven. Hanks of hemp fiber would be drawn through the spikes, which combed out most of the remaining stem debris, and collected the shorter fibers (called 'tow') among the base of the spikes, while consistently orienting the long fibers for spinning or rope making. Mechanized hacklers were also often built as part of a complete fiber-processing machine. These devices generally used drums with spikes, which effectively cleaned and separated the fiber, but they didn't orient the long fibers in a consistent manner, and thus the fiber was less valuable unless a final hand-hackling step was undertaken.
The water-retting process yielded more uniform fiber with a direct cost of even more labor. The U.S. Navy paid a premium for water-retted hemp in the early 1800s, but farmers found that the work was so hard that it was simply not worth it.