How To Grow Industrial Hemp

Growing industrial hemp either commercially or on a large scale is an exciting opportunity and for the farmer an educated decision is the best plan when considering hemp. Industrial hemp has many benefits and has a great market potential.

What is industrial hemp?

Industrial hemp is classified as non-drug Cannabis sativa varieties, whose fruit is technically an achene, or a single-seeded fruit similar to a sunflower. Both the seed and hemp’s tall stalk provide significant carbohydrate feedstocks for a wide variety of industrial purposes that are used in several countries. The oil pressed from hempseed in particular, is a rich source of polyunsaturated omega-3 and omega-6 fatty acids, which are essential for human health. These same fatty acids in hempseed oil make it a fine drying oil that is used in the production of paints, varnishes, and other coating materials. Plastic flooring such as linoleum and similar materials have been made from hempseed oil, and other non-food uses of hempseed oil are similar to those of linseed oil (flaxseed oil).

Hemp is a crop that people don’t usually think about growing. Mainly for the snigger factor – the associations with hemp’s THC rich cousin – marijuana.

But most people don’t know the wonderful qualities and the amazing potential of the hemp plant.

The benefits to you as a farmer growing industrial hemp include:

Industrial hemp doesn’t require herbicides. Because hemp is such a fast growing plant it provides a canopy within 5-6 weeks that most weeds cannot penetrate, meaning less costs for you.
There are fewer biological pests to industrial hemp. So you don’t have to spend a fortune in insecticides.
Hemp can be used to restore depleted soils. Studies have shown that hemp can be used as a “mop” crop on soils that have been heavily damaged by chemical use.
Hemp is easy to grow as it is a strong and hardy plant. So that means less stress for you.
You don’t need special machinery to harvest hemp. A simple brush cutter is enough for some crops and means that as a farmer you probably already have easy access to a harvester.
You can grow hemp on as little as 1 hectare or much bigger depending on the land available to you.
Industrial hemp is profitable. The demand for hemp means that you can make money compared to most crops with declining economic returns.
Industrial hemp is being recognised by governments around the world as being an ecologically friendly crop. This means you can do your bit for the environment while still putting money in YOUR pocket.
There are professional bodies promoting the growing and use of hemp. This is raising the profile of hemp and making it easier to get government licenses to grow the crop.

Basics of Hemp Cultivation

Hemp prefers a mild climate, humid atmosphere, and a rainfall of at least 25-30 inches per year. Good soil moisture is required for seed germination and until the young plants are well established. Hemp responds to a well drained, loam soil with a pH (acidity) above 6.0. Neutral to slightly alkaline (pH 7.0 – 7.5) is preferred. The higher the clay contents of the soil, the lower the yield of fibre or grain produced. Clay soils are easily compacted and hemp is very sensitive to soil compaction. Young plants are very sensitive to wet soils or flooding during the first 3 weeks or until growth reaches the fourth internode (about 30 cm. tall). Water-damaged plants will remain stunted, resulting in a weedy, uneven and poor crop.

Poorly structured, drought-prone sandy soils provide very little natural fertility or support for the plant. Accordingly extra nutrients and water are required to achieve maximum yields on these soils. The cost of irrigation on sandy soils may make production uneconomical.

The soil can be worked and planted as soon as the ground is dry enough to avoid compaction. A shallow, firm seedbed allows seed to be placed at a uniform depth, resulting in a more even seedling emergence. Industrial hemp is normally sown using a standard grain drill. Plant seed at a depth of 2-3 cm. Optimum soil temperature at that depth for fast germination is 8-10oC, although hemp seed will germinate at 4-6oC.

Industrial hemp that is planted for fibre is usually sown in 15-18 cm (6-7-in.) rows, using every run of the drill. Optimum final stand is about 200-250 plants/m2. Early seeding (as soon as soil conditions are appropriate) is recommended. Researchers recommend a minimum seeding rate of 250 seeds per m2. 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.

When should you plant hemp seeds?

Industrial hemp is day-length sensitive, resulting in greater vegetative growth if planted earlier. Seeding should not begin until soil temperatures have reached a minimum of 42 – 46 °F (6 – 8°C).Hemp seed germinates within 24 to 48 hours, and emerges in 5 to 7 days with good moisture and warm temperature. Hemp grown for fiber should be seeded as early as possible while hemp for grain should be seeded later to minimize the height of the stalk.

Hemp requires a lot of moisture. Measurements indicate the crop needs 300-400 mm (10-13 in.) of rainfall equivalent. Since that amount of rainfall may or may not occur during your growing season, it is important to make use of early soil moisture and to obtain early ground cover to reduce surface evaporation, as well as to maintain good weed control.

About half of this moisture is required during flowering and seed set in order to produce maximum grain yields. Drought during this stage reduces seed set and produces poorly developed grain heads. Continued drought results in low yields of light grain.

During the period of vegetative growth, hemp responds to daytime high temperatures with increased growth and increased water needs. It is said that after the third pair of leaves develops, hemp can survive daily low temperatures as low as -0.5°C. for 4-5 days.

Hemp requires approximately the same fertility as a high-yielding crop of wheat. Research is continuing to define the exact nutrient requirements. Apply up to 110 kg/ha of nitrogen, depending on soil fertility and past cropping history. Research to date supports the application of 40-90 kg/ha of potash for fibre hemp. Base your phosphorus (P205) and potash (K20) applications on a recent soil test. To interpret soil test information, follow the nitrogen, phosphate and potash recommendations for winter wheat in OMAFRA Publication 811, Agronomy Guide for Field Crops.

Hemp growers in some places may benefit from adding sulfur. It is important to balance the nutrients applied with the crop requirements and with each other. Excessive nitrogen, combined with inadequate potash, for example, can result in stalk breakage and loss of the crop.

About 42% of the plants’ biomass returns to the soil in the form of leaves, roots and tops. These contain over half of the nutrients applied to the crop. Many of these nutrients will be available to help feed the following crop.

How do you control weeds?

Industrial hemp is an extremely efficient weed suppressor. No chemicals are needed for growing this crop. Industrial hemp is a low maintenance crop. There are no registered chemicals for weed control in hemp cultivation. A normal stand of 200 to 300 plants per square meter shades out the weeds, leaving the fields weed-free at harvest.

Hemp requires approximately the same fertility as a high-yielding crop of wheat. About 42% of the plants’ biomass returns to the soil in the form of leaves, roots and tops. These contain over half of the nutrients applied to the crop. Many of these nutrients will be available to help feed the following crop.

Diseases and Pests

More than 50 different viruses, bacteria, fungi and insect pests are known to affect the hemp crop. However, hemp’s rapid growth rate and vigorous nature allow it to overcome the attack of most diseases and pests.

As the acreage of industrial hemp and alternative disease hosts increases in a given area, the population of disease or pest organisms will tend to increase. The following pests have been noted in hemp fields in Ontario. Botrytis cinerea (grey mold) and Sclerotinia sclerotiorum (white mold) are common molds affecting industrial hemp. Sclerotinia also affects edible beans, canola and sunflowers. It has been found on more than 10% of plants where industrial hemp followed canola. Sclerotinia spores (sclerotia) may be spread by combines, other harvesting equipment and straw. Fusarium, the pink mold found on corn and wheat, has been seen on the roots of hemp plants. The effect that an additional host crop will have on the viability of these crops may not be known until industrial hemp is grown more intensively in bean and canola-growing areas.

European Corn Borer has affected some stands in southern Ontario and grasshoppers have done some damage to hemp crops in Northern Ontario. Bertha Army Worm (Mamestra configurata) has been a pest in Manitoba and could find its way to industrial hemp crops in northwestern Ontario.

Other diseases and pests have been identified, with varying degrees of severity, in other provinces. Crop rotation would appear to be a good cultural practice to avoid disease build-up until more is known about hemp’s susceptibility to disease organisms. A 4-year rotation is recommended. Do not grow hemp on the same fields following canola, edible beans, soybeans or sunflowers.

Wind and hail damage can be significant to the industrial hemp crop. Tall plants with lots of upper leaf mass can be bent quite easily by mid-to late-summer storms. Broken plants will recover partially if not broken too low. This results in significant variability in plant height and maturity at seed harvest time. Small plants damaged by hail in 1996 recovered quickly and developed quite normally if they were not severed below the first node. Weather stresses may result in higher THC levels in the remaining crop.

Yield

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.

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.

Farmers and business professional agree; industrial hemp cultivation has an enormous upside for creating jobs, revenue and products. We just have to get past the legal stumbling blocks that keep industrial hemp cultivation and harvest from being an acceptable and legal crop in the United States.