Source: 1907 Cyclopedia of American Agriculture - A popular survey of agricultural conditions, practices and ideals in the United States and Canada. Edited by L.H. Bailey
Author: J.N. Harper
Pages: 282, 377-380

Hemp (see article on Hemp).

Hemp is a soft fiber obtained from the inner bask of the hemp plant, Cannabis sativa, Linn., an annual belonging to the Morace or Mulberry family. Originating in central Asia, hemp is now cultivated for fiber production in China, Japan, Russia, Hungary, Italy, France and the United States. In this country hemp is one of the principal crops of the blue-grass region in central Kentucky, 10,000 to 20,000 acres being grown there each year. Smaller areas, rarely exceeding a total of 1,000 acres, are grown nearly every year in Michigan, Minnesota, Nebraska and California.

The annual production of rough hemp in the United States amounts to 4,000 to 10,000 tons, valued at $480,000 to $1,200,000. The annual average quantity of hemp imported in the past ten years is 4,982 tons, with an annual average value of $716,264. There has been a general upward tendency in prices in the past fifteen years. With a more general use of harvesting machinery and fiber-cleaning machinery, now being introduced, the crop may be grown more economically and its cultivation will doubtless extend over much wider areas.

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HEMP. Cannabis sativa, Linn. Urticace. Figs. 566-571. [See also Fiber plants.]

By J. N. Harper.

An annual dicious plant, reaching a height of ten feet and more, grown for its long bast fiber, and for its seeds. Staminate flowers drooping in axillary panicles, having five sepals and five stamens; pistillate flowers in short spikes, with one sepal folding about the ovary. Leave digitate, with five to seven nearly linear, coarse-toothed leaflets. Hemp is probably native to central Asia.


Hemp has been cultivated for centuries as a fiber plant. It was grown by the early Greeks and probably by the ancient Egyptians. It has been grown in this country for about 130 years, the seed having been brought from France. During this time, its cultivation has been confined chiefly to about twelve counties in central Kentucky, in what is known as the blue-grass region. For the last forty or fifty years, however, the industry has spread into a number of other states, notably Missouri, Illinois, Nebraska, Oklahoma, Minnesota, New York and California. Notwithstanding this extension of the industry, nine-tenths of the hemp crop of America is still grown in Kentucky.

During the years it has been grown in Kentucky, probably no other crop has brought an equal revenue. A few years before the Civil War it contributed more to the wealth of central Kentucky than all other crops combined. At that time, Kentucky produced annually 38,000 tons, with a gross receipt of $2,280,000. During the war the industry declined but revived a few years later, and again declined owing to the use of iron and jute in the bagging of cotton. Hemp is now used largely for making burlap, twine and carpet warp.


According to the Twelfth Census there were in 1899, 964 farms producing hemp, with an average acreage of 16.6 and a total acreage of 16,042. The average production per acre was 732 pounds, worth $34.06, or 4.6 cents per pound.

The figures for hemp in the Twelfth Census (1900) are as follows:





































The soil. - While hemp will grow on almost any land containing a large amount of humus, it does best on well-drained silurian limestone soils. In Minnesota it thrives on drift soils. The moisture content is the important factor. The soil should be prepared thoroughly by breaking with a turning plow, plowing about six to eight inches deep, and by repeated harrowings and rolling.

Hemp grows so tall and dense that it kills weeds by smothering them better than any other farm crop. A good growth of hemp is effective in killing even Canada thistle and quack-grass. It leaves the soil in excellent condition for any succeeding crop.

Seeding. - The best results are secured by sowing with a seven-inch wheat drill, running it both ways. The seed is sown at the rate of one bushel per acre. It is sown about two inches deep. After sowing, the land should be rolled. Hemp should not be sown very thick, because in thinning itself it will crowd out many plants and the size of the hemp stalks will not be uniform. The best fiber is obtained from stalks about one-half inch in diameter; if a thin stand is secured, the stalks frequently will grow to be three-fourths of an inch in diameter. Hemp drilled in gives a much more uniform stand than when sown broadcast, because all of the seeds are placed at a depth to have sufficient moisture to insure immediate germination, and the young plants get an even start. Repeated experiments have shown that it does not pay to till hemp that is intended for fiber.

The earlier the seed is planted in the spring the more assurance there will be of a good crop. Hemp requires a large amount of moisture and should be high enough to shade the ground and thus conserve all water that may fall in the early summer. The average time of planting for eight years at the Kentucky Experiment Station was April 25. The young plants began to come up in about one week's time.

It has been found by long experience that the seed that gives the best results is secured from China. The Kentucky Experiment Station has tested the value of a number of Japanese varieties, but none has given as good results as those from Chinese seed. The first year the imported seed is planted the yield is much less than it is in succeeding years. Growers say that after the Chinese hemp has been grown for a number of years it degenerates and they seek newly imported seed. There are no well marked varieties.

Seed-growing. - The hemp that is planted for seed is sown on the river-bottoms. A narrow strip along the Kentucky river produces nearly all of the hemp grown in America for seed purposes. About two quarts per acre are sown. This is often planted in hills, seven feet apart, in rows six to eight feet apart. About four stalks are permitted to grow to the hill. This hemp is carefully cultivated and kept free from all weeds and grasses. The seed is used in the making of oils for paints, for bird and poultry food, and various other purposes. The yield of seed is fifteen to thirty bushels to the acre. As much as forty dollars per acre is often realized from hemp seed. The seed must not be stored in bulk or it will heat.

Fertilizers. - The Kentucky Station has experimented for a number of years on the use of commercial fertilizers on hemp, and the results show that, by the use of 160 pounds of nitrate of soda per acre, three to four hundred pounds more fiber can be grown to the acre than on unfertilized land. When 160 pounds of nitrate of soda and 160 pounds of muriate of potash are used together, at least four to five hundred pounds more fiber are secured than on the unfertilized areas. Acid phosphate does not show a material increase. Nitrate of soda gives better results than does sulfate of ammonia or dried blood. The prime requirement is for nitrogen, and it should be furnished by applying commercial fertilizers, or by barnyard or green-manures. A leguminous crop can be alternated with the hemp, and in parts of the South this can be done in the same year.

Cutting and handling.

The first blossoms appear about the first week in July, and hemp sown April 25 will be ready for cutting about the first of September. Most of the hemp grown in Kentucky is still cut by hand by means of a knife made especially for this purpose. However, much has recently been cut by especially designed machinery. The yield from the handcut field is greater than that from the machinery-cut field, and some farmers maintain that there is enough difference to make up for the greater expense. The heaviest fiber is found on the internode next to the ground, and if the stubble is left any length, a great quantity of fiber is lost. It usually costs about one dollar per acre to cut by machinery and three dollars per acre to cut by hand.

After the hemp is cut, it is spread evenly over the ground, the butts being placed down the hill if there is a slope. The stalks are placed in parallel lines. In about one week it is sufficiently dry to rake up into small bundles. These bundles are tied with small stalks of hemp and are placed in shocks (Fig. 569) or stacks (Fig. 570). The Kentucky Experiment Station has shown that it pays to stack the hemp, as the loss of fiber is not so great and the quality is much improved. Stacked hemp rets more evenly and makes a much better fiber than when shocked. In the latter case, too much of the outer layer sunburns and over-rets. The shocks are liable to blow down, greatly to the damage of the crop. The shocked hemp, however, is much less expensive to handle and can be spread out at different periods, so that the quantity retted at one time can be controlled.

If the hemp is allowed to remain on the ground too long after cutting, it will sunburn and the quality will be destroyed. It requires considerable judgment to stack hemp to avoid the sunburn. Care should be taken not to stack it before it is sufficiently dry, as it will heat in the stack with much injury to the quality.

Retting. - About the middle of November or the first of December, the hemp is taken from the stack and spread over the ground as before stacking, to ret, a process which separates or liberates the bast. If the weather conditions are favorable, it will ret in about two months sufficiently to break. Ideal weather conditions for retting are alternate freezing and thawing, with an occasional snow that does not remain long on the ground. Early and late retting are not so good as winter retting; and hemp retted during heavy freezes is much better than when rain-retted. After the hemp has retted sufficiently to allow the fiber to break readily from the hards (or "hurds"), it should be placed in shocks to prevent further retting. The artificial methods of retting have never been completely successful.

Breaking. - The fiber is removed or extracted from the other tissue by the process of breaking. Most of the hemp of Kentucky is still broken by the old-fashioned hand-brake that has been in use for more than one hundred years. Large sums have been spent in trying to devise machinery for this operation, but so far most of the attempts have failed. Within the last year or so, however, machines have been designed that promise successfully to break the hemp.


After being broken in the field, the hemp is tied up in hanks of six to eight pounds. These are put in about 150-pound bales, which are taken to the market, where the hemp is rehandled by the dealer. The rehandling consists in running the hemp through hackles of various degrees of fineness. The hackled hemp is shipped directly to the twine manufacturer. The best hemp fibers, which are water-retted, come from abroad, especially from Italy and France.

Returns per acre.

Sufficient seed to sow an acre costs about $3; the breaking of the land costs $1.25; harrowing, 50 cents; breaking and rolling, 50 cents; drilling the seed, 50 cents; cutting, $3; tying and shocking, $1.25; spreading, 50 cents; taking up and shocking, 50 cents; putting in stacks, $1; breaking, $1 per hundred, or about $15 per acre, thus making the total cost $27 per acre. Twelve hundred pounds is considered a good crop, and 1,800 pounds is often produced. The average price is about five cents per pound, making a gross income of $60 to $90 per acre, or a net income of $33 to $63 per acre.


The hemp plant is subject to few enemies. There is a parasitic plant that is causing a great deal of damage to the crop in central Kentucky. This parasite belongs to the broom rapes. It has been discussed in several bulletins issued by the Kentucky Station. Cutworms and a small fly (Pegemyia fusciceps) sometimes damage it seriously.

Methods employed in Nebraska, California and Minnesota.

At Havelock, Nebraska, where hemp follows hemp or a crop leaving the soil in equally good condition, the land is prepared and the seed sown and covered at one operation. A traction engine draws a gang of plows followed by a harrow, then a special drill and a second harrow to cover the seeds and settle the soil. The hemp is cut with ordinary mowing machines with an attachment to throw the stalks smoothly in the direction the machine is going. The stalks lie where they fall until retted. They are then raked up with horse-rakes and taken to the power brake, consisting of fluted rollers followed by beating wheels, which prepares the fiber in the form of long tow. In California hemp is cut with special self-rake reapers, bound and set up in shocks, until conditions are favorable for retting. It is then spread for dew-retting and afterward broken on the Heaney hemp brake, similar to the one at Havelock, making long tow. At Northfield, Minnesota, hemp is cut by self-binders of special construction and, after curing in the field, is water-retted in tanks and broken by machinery, producing a light yellowish fiber somewhat like Italian hemp.


M. Molliard, Experimental Investigations on Hemp, Bul. Soc. Bot., France, 50, 1903; Viner, Experiments with Hemp, Khozyaene, 1901, No. 47, 48; Rev. in Zhur. Opuitn. Agron. (Jour. Expt. Landw.), 3 (1902), No. 2, pp 248-249; Dewey, The Hemp Industry in the United States, United States Department of Agriculture, Yearbook 1901 [Link: 1901: USDA LYSTER DEWEY 13 PAGE ARTICLE ON HEMP], pp. 541-554; Boyce, Hemp, - a Practical Treatise on the Culture of Hemp for Seed and Fiber, with a Sketch of the History and Nature of the Hemp Plant, Orange Judd Company, New York, 1900.