Industrial Hemp Production Essentials
Hemp grows best on weed-free, fertile, medium-textured soils, in the absence of herbicide residues. When grown for grain, growers should select fields that were not preceded by wheat, as the kernels will cause contamination. Organic hemp crops are best preceded by perennial alfalfa breaking with adequate phosphorus levels and/or a green manure/cover crop.
Choosing the best variety for a specific environment, end use(s), and geographic location is of the utmost importance in the potential success of a hemp crop. Hemp production data across regions is currently limited, so growers need to rely on local information and any available research data. As hemp is a multipurpose crop providing seeds, fibre, and cannabinoids, choosing the best variety with the end use in mind is paramount. Once determined, further analysis is required to compare the different varieties to determine the best fit.
Seed hemp between 0.5” and 1″ into moisture after the soil temperature is consistently 10°C (or 50°F) or higher. Hemp is moderately frost-tolerant. Seeding dates for hemp in Canada vary from May 15 to June 15, while germination can be expected in 2 to 4 days and emergence within 4 to 7 days. Reduce airflow on air distribution seeder systems to prevent seed damage. Suggested seeding rates are 25 to 30 lbs/acre for grain production and 40 to 45 lbs/acre for fibre production. Government regulations require the use of pedigreed seed in Canada.
Stand establishment continues to be one of the main issues associated with hemp production. Key environmental factors that influence early growth and development of hemp include sunlight, temperature, soil condition or tilth, and soil moisture. There are strategies available to growers to improve stand establishment and overcome environmental challenges, including field selection, variety selection, seed bed preparation, seeding depth, fertility rates, fertility placement, and seeding date.
Hemp responds positively to increasing soil fertility but is somewhat sensitive to seed-placed fertilizer. Conventional producers should fertilize using rates similar to canola, adding 10-20% more N. Organic producers should work towards building soil fertility through a diverse crop rotation and supplemental manure/compost if available. Grain yields are very dependent on fertility and moisture, generally ranging from 900 lbs/ acre to over 2,500 lbs/acre under conventional production. Expect 60% yield of dryland canola. Organic hemp grain production yields generally vary between 500 and 1,500 lbs/acre.
Weed, Disease, and Pest Management
Weeds are best controlled through proper field selection, a pre-seeding burn-off, adequate rates of fertility, and selecting the best-adapted hemp variety based on height and vigour. In Canada, hemp has few disease and pest problems but is host to Sclerotinia and Botrytis during wetter years. Registered herbicides for grain production are limited to Assure II and Edge in Canada. Other pesticide trials are ongoing through the Minor Use Program.
Harvest, Drying, and Storage
In order to minimize stalk fibre wrapping when seed is higher moisture, most producers prefer to straight combine hemp. Depending on variety and combine model, threshing is recommended from 10-17% moisture (safe storage is considered to be 9% seed moisture). Some minor fibre wrapping may occur depending on hemp variety and field conditions with 25- to 30-year-old combines (JD 9600’s and Case IH 2188’s), with very little or no wrapping with the newest combines (CIH 8 series and JD S series). It is recommended that you dry hemp grain immediately off the combine to 9% moisture using aeration or supplemental heat aeration and turn and/or aerate hemp grain at the changing of the seasons (spring/summer) to reduce moisture migration and spoilage. Move and unload hemp keeping the auger full and reduce speed. Large-diameter augers or belt conveyors are less damaging to hemp seed.
Industrial hemp producers should be aware of local and national regulations related to hemp production. In Canada, Health Canada Industrial Hemp License applications can be completed online using Health Canada’s Cannabis Tracking and Licensing System (CTLS).