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For grain production, desired final plant population is around 100-150  plants/m2. Like fibre hemp, seeds are still planted in 15-18  cm (6-7 in.) rows. Soil temperature determines the optimum planting date.  This date may range from late April in Kent and Essex counties to late May in Northern Ontario. Do not plant after the first week of June. Observations in Northern Ontario indicate that grain yield may not respond as positively to early planting as does fibre yield, but early planting may help to         advance the harvest date.


Tamm determined that hempseed needs a minimum temperature of 1-2o C for germination and emergence. It should not be sown until the soil temperature rises to 10o C. The optimum temperature is 35o C; the maximum is 45o C, at which temperature the seeds sprout within 12 days. Young hemp plants can survive frost as low as -5o C, but the plants will stop growing even if warm weather follows. The temperature range for hemp growth is 19-25o C (66-77o F). Hemp enters into its rapid growth stage (about 2 inches/day) when the average temperature rises to 16o C (61o F). If southern varieties of hemp are grown in northern latitudes, however, the fiber might not attain technical maturity within 110-115 days, and certainly their seeds will not ripen. The farmer must consider this when selecting a hemp cultivar for his location.

FROM A VERY GOOD STUDY: http://www.rexresearch.com/hhusb/hh2cul.htm



Production is estimated using information on yield and acres harvested. Industrial hemp yield

(grain or fibre) varies with variety, plant population, soil conditions, timing of harvest, and annual

climatic conditions. The highest seed yield recorded to date in Canada has topped 2,000 lbs per acre; an average yield is between 600 to 800 lbs per acre, but rising (Canadian Hemp Trade Alliance). An acre will also produce an average of 5,300 lbs of straw, which can be transformed into about 1,300 lbs of fibre.


There is a Hungarian expert. He states: We called this cultivar “UNIKO-B”. It is, in fact, a “single-cross” between Kompolti and Fibrimon, but it is the F2 generation which is commercialized. Von Sengbusch and Hoffmann described the phenomenon, but they did not think of its practical use. In Kompolt we make the cross between Kompolti and Fibrimon on a surface of 5 hectare (ha), this yields 2,500 kg of F1 seed. The F1 seed is sown on a surface of 500 ha, yielding 400,000 kg of F2 seed, which is used to sow 3,000-3,500 ha of fibre hemp. So F1 ratio is five will see 500 (10 to 1) and F2 is 500 to 3,500 (or 3,000) so the ratio is 6 or 7 to 1.

Intervie with Ivan Bocsa,   http://druglibrary.org/olsen/hemp/iha/iha01215.html



Fiber hemp grows best in well        drained soil that doesn’t crust and that holds moisture        within two or three inches of the surface. (154) Illinois        experts recommend silt loams and clay loams. (155) Iowa        experts emphasize good drainage, (156) noting that soggy        soil produces weak fiber. (157) A USDA agronomist        declared Missouri’s soil and climate        “favorable” for commercial hemp. (158) In the        1940’s , northwest and southeast Missouri were considered        the best areas in the state for commercial hemp        production. (159) An acre that produces 75-80 bushels of        corn can produce 2.5-3.0 tons of hemp, (160) but land        that produces slightly lower corn yields may produce far        lower hemp yields. (161) Fertility is crucial to hemp        yield.

Although nitrogen appears        unimportant to growth of wild hemp (162), good nitrogen        supply improves yields of cultivated stalk. Commercial        nitrogen fertilizer works, and so does crop rotation.        (163) Planting hemp after alfalfa or clover works well,        planting after soybeans helps to a lesser extent. (164)        Phosphorus and potassium can be helpful, and manure is        universally recommended. (165) Authorities note, however,        that fertilizers may increase yield of stalk but decrease        yield and quality of fiber from the stalk, (166) thus        fertilizer application requires knowledgeable judgment.        Although hemp crops remove quite a bit of nutrient, (167)        hemp sheds leaves that return nutrients to the field, and        upper leaves remaining on stalks drop to the ground as        part of the field “retting” process described        below. (168) In field retting the soil also recovers        about 20% (by weight) of organic material from stalks,        and farmers can plow stubble under. (169) Hemp’s net        extraction from soil fertility is thereby less than many        other crops (170) and is considered comparable to corn.        (171) Corn, incidentally, does well when planted after        hemp. (172) During the 1970’s in France winter wheat        commonly followed hemp. (173) French growers find that        hemp clears weeds and cereal parasites from wheat fields,        and the deep hemp roots help with tilling. (174) Hemp        crops are noted for improving physical condition of soil.        (175) Indeed, hemp has been recommended as a crop for        soil building purposes. (176) U. S. hemp production fell        after World War II because planted acreage fell, not        because soil fertility declined. (177)

Fields can be plowed in fall or        spring, though some authorities recommend fall. Hemp        thrives in the type of seedbed prepared for alfalfa.        (178) Seed can be broadcast or planted by seed drill no        deeper than one inch; drilling improves yield. (179) Seed        is about the size of wheat, 44 pounds to the bushel, and        33-55 pounds per acre are recommended for fiber crops.        (180) Higher seeding rates don’t increase the yield of        stalks per acre, but can increase yield of fiber from        stalks. (181) Experiments suggest that treatment with        seed disinfectants have small or zero effect on yield.        (182) In the Midwest the best time to plant hemp is after        oats and before corn. (183) The first week of May may be        ideal around Ames, Iowa. (184) Growing season is 120        days.

Hemp grows quickly and reaches        heights of 5 to 15 feet; for fiber production, height of        6 to 8 feet and stalk thickness of 0.25 inch is ideal.        (185) Fiber hemp is planted in thick stands (20 or more        plants per square foot) that smother weeds. Few diseases        or pests trouble crops. Once seedlings appear, farmers        rarely must do anything until harvest. Hard rain is        unlikely to lodge hemp, but strong hail can damage crops        (by destroying leaves and thereby harming plant growth).        (186) Fiber hemp needs ample moisture, and drought harms        crops; a climate with at least 30 inches of annual        rainfall is recommended. (187) In the 1920’s authorities        reported irrigation to be feasible. (188)

Traditionally in the United        States, mills that contracted for crops rented mechanized        hemp harvesting equipment to farmers, relieving farmers        from the large up-front cash outlay that purchase of such        equipment would require. (189) In the 1940’s equipment        rental in the federal program was $ 4 to $ 7 per        harvested acre, deducted from crop payment by the mill        rather than paid up-front by the farmer. (190) Private        mills had similar arrangements with their growers. (191)        Harvest starts in late August and continues through        September. American authorities recommend harvesting        while pollen sheds and before seeds form. (192) Before        1967 French growers harvested after seed matured, but        French practice now follows the American one. (193)

If harvested stalks are stacked        and stored in dry conditions they will keep for years.        They do not have to be processed right away. (194)

Normally, harvested fiber stalks        must be “retted.” In retting, stalks are        commonly left on the ground for weeks or months so        weather may start to decompose them, making it easier for        breaking and scutching mills to remove fiber from stalks.        Field retting is sometimes called dew retting. Heavy dew,        “reasonably high” humidity , and intermittent        rain are important for field retting. (195) Stalks can        also be retted underwater in ponds or tanks. This method        produces better fiber than field retting, but in the        1940’s American technology did not make water retting        economical in comparison with field retting. (196)        Research at Iowa State College established that        controlled water retting could be accomplished in 36        hours. (197) The head of the federal hemp program        declared in 1944, “If a program of controlled        retting can be developed, I am very confident that there        is no limit as to the tonnage that can be grown        successfully and profitably in this country.” (198)        One account from the 1970’s noted a Swedish water retting        operation with capacity for 150 tons of stalk at any        given time, producing 33 tons of fiber per day. (199)        Some work has been done in processing unretted hemp.        (200) Retting is universally considered the hardest part        of hemp farming, because shrewd judgment is needed to        determine when the crop is properly retted. Fiber yields        from improperly retted crops are inferior.

In the 1980’s Canadian Hemp        Industries Corporation demonstrated a decorticator that        stripped fiber from stalks upon harvest in the field        without retting. (201) Such technology eliminates the        riskiest part of raising hemp fiber crops, making them        more economically viable than they were in the 1940’s.

After stalks are field retted,        they are bound and shocked. These steps typically occur        at the peak of soybean and corn silo filling, and require        more labor than corn harvesting, but 1940’s farm        operations handled the labor demand. (202) Until around        World War I hemp farming was labor intensive, but        mechanical harvesters and mill machinery dramatically        reduced labor requirements. In the 1920’s mechanized        Wisconsin hemp farmers were able to compete with cheap        foreign labor. (203) In 1943 a typical Illinois hemp farm        required 19.4 man hours per acre for the season. (204)

Farmers send bales of retted        stalks to breaking mills.

As a general rule, the higher the        yield of stalks per acre, the higher the quality of fiber        from that yield. (205)


Although Missouri had large hemp        fiber crops in the 1800’s, the last remnants of the        state’s hemp production in the 1940’s supplied seed for        fiber growers. (206)

Climate and soil types        recommended for fiber production are essentially the same        for seed production, although ample soil calcium is        emphasized for seed. (207)

Seed hemp is commonly planted in        hills 4 or 5 feet apart, thinned to 3-5 young plants.        (208) Plants become bushy.

With American varieties growing        season for seed is at least 180 days. (209) Traditional        harvest method is to cut the plants by hand 8-24 inches        above the ground, and shock small bundles of them. After        drying (a process taking a few days to 3 weeks) each        shock is put on a tarpaulin and seeds are manually beaten        off with sticks. “While this seems a rather crude        way of collecting the seed, it is doubtless the most        economical and practical method that may be devised. The        seed falls so readily from the dry hemp stalks that it        would be impossible to move them without a very great        loss. Furthermore, it would be very difficult to handle        plants 10 to 14 feet high, with rigid branches 3 to 6        feet in length, so as to feed them to any kind of        thrashing machine.” (210) Seed for new crops is sent        to a cleaning mill. Seed for oil is shipped to a crusher.

Although traditional U. S.        cultivation practice requires farmers to choose between        fiber or seed production, foreign seed growers have        harvested seed stalks for low grade fiber. (211) Before        the mid-1960’s such practice was also traditional among        fiber growers in France, where fiber is used for paper        rather than textiles, and can therefore be of lower        quality. Seed harvested this way is used for animal feed        and for planting new crops. (212) American experience        indicates that such seed is poor for new crops, however.        (213)


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