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For textile applications, cut hemp in the early flowering stage or while pollen is being shed, but before seed sets. Fibre that is cut after seed harvest will have lignified considerably and is usable only in some non-woven industrial fibre applications. In dioecious varieties, the male plants die back after shedding pollen. This results in lower fibre yields if the straw is cut after grain has matured.
On small acreages, good quality sickle-bar mowers and hay swathers have been used to cut hemp. Frequent plugging has been a constant problem with this equipment. It is important to keep knives sharp and in good repair at all times. As acreage increases, more sophisticated equipment may have to be imported or developed.

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Maturity varies from 80 to 120 days depending on variety and date of seeding. Hemp is a photosensitive plant, thus flowering of the plant is triggered by the shorter day lengths .
The actual process of harvesting starts approximately six weeks after flowering or when it is determined that the seed is properly ripened.
The fiber from stalks grown for seed production is stiff, coarse and brittle, especially in the male dioecious variety as they died soon after pollination was completed. This coarse fiber may be good for fiberboard and other products, as it is stronger than younger fiber.



Air dry stem yields in Ontario have 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. Researchers feel earlier planting, optimum production management and more suitably adapted varieties can result in higher yields.Approximately one tonne of bast fibre and 2-3 tonnes of core material can be decorticated from 3-4 tonnes of good quality, dry retted straw.

Yield of fibre depends on both the stalk yield per hectare and the fibre content of the stalk. Varieties differ in the amount of actual fibre they contain, and on the ratio of bast fibre to core materials (hurds). Dioecious varieties originating in southern Europe give the highest stalk yields. Further processing may be required to attain the quality of fibre needed for some end uses.

Hemp Harvesting

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