Hemp from Field to Fabric

Hemp has demonstrated that it can have a significantly positive impact upon the environment and the lives of people. Let s examine how friendly the processes are for converting hemp plants into fabric and garments. The major steps in taking hemp from the field to fabric fashions are:

Growing Hemp. 

Hemp has been described as "Flax with attitude". It's quick growth -- germination to maturity takes between 80-120 days (depending on variety, latitude and field/climate factors) - to reach heights of up to 15' is one of hemp's most impressive features. On a summer day, some claim that you can almost see hemp growing. Unlike cotton, hemp grows in many climate zones. It does especially well in regions where corn is grown. The plant has a short growing season of three to four months. 

Hemp is grown densely packed with up to 150 plants per square meter so that tall plants containing long primary bast fibers will be produced. By the time they are ready to be harvested, the hemp plants have reached a height of two to four meters. Hemp requires no pesticides to aid in its growth, as it is naturally pest resistant. It has been known to reduce pests in future crops when grown in rotation. Hemp requires no herbicides because it is grown so densely that it smothers out other plants. Hemp also requires little or no fertilizer and it returns 60-70% of the nutrients it takes from the soil.

Weed Control. 

Herbicides are not needed for growing hemp. Hemp grows very quickly and its dense foliage chokes out most weeds. Field choice, pre-seeding tillage, shallow seeding, and packing after seeding all help to ensure that the hemp stand will emerge quickly and uniformly to gain advantage over the weeds.

Insect Control. 

Bertha armyworn (Mamestra configurata) may be a significant pest to industrial hemp. Bertha armyworm is a cyclical pest of canola and other crops in Canada. Other pests that have been observed include Lygus plant bugs, cutworms, and grasshoppers. Organic farming methods can be use to control these insect pests.

Disease Control. 

Diseases that can attack hemp include Sclerotinia sclerotiorum and Botrytis cinerea. Wild mustard and volunteer canola, or adjacent canola stands can be the source of Sclerotinia stem rot infections. Adequate rotation with non-susceptible crops, ensuring seed free of disease organisms, and management of host species like wild mustard and volunteer canola are the key approaches to manage disease risk. The lower plant densities used for seed production should be less risky for sclerotinia than higher density plots for fiber production, but because fiber crops will be cut by mid-flowering the disease may be of less consequence.

Harvesting Hemp. 

For hemp, there are two products to be harvested  the hemp fiber and the hemp seeds. The highest quality fiber is obtained by cutting at early to mid flowering. Mowers with the crimping rolls removed and round-balers may be suitable for low to medium quality end uses. The best approach for harvesting appears to be combining when shelling becomes evident and running the header cutter bar 4 to 5 feet above the ground. Care should be taken to avoid dehulling the seeds in the combine, since dehulled seed is more prone to spoilage or quality loss in storage. After combining, the remaining stalk material can be cut and baled. The mature stalk contains a coarse, low-grade fiber compared with stalk cut at early flowering, but is still marketable.

Drying and Storage. 

Freshly threshed seeds may have an average moisture content of 16 - 20%. The moisture content at which hemp seeds/grain can be considered "dry" is not known precisely. Seeds should be dried to between 12% and 10%. Air flow through hemp grain should be relatively free. Because the grain may be tough when it is combined, drying should commence as soon as possible after harvest to ensure that quality remains high. Large fans, some with heaters, are used to dry the hemp seed grains.

Grain Cleaning. 

Ultimately hemp grain seeds need to be cleaned to a rigorous standard for food processing. Conventional seed cleaning apparatus should be able to deal with most foreign material or weed seed problems. If a significant amount of green foreign material is present in the harvested grain, the grain should be pre-cleaned prior to storage to avoid spoilage. Some contracting companies may arrange to do the cleaning themselves.

Grading. 

Grading standards have not been determined for hemp grain seeds. Buyers will be concerned about foreign material, seeds with adhering bracts, dehulled or otherwise damaged seeds, and off-type crop or weed seeds.