Growing Hemp
On every continent but Antarctica, there is renewed interest in growing hemp. One of the best authoratative books for growers is Dr. Ivan Bocsa and Michael Karus’ book entitled Cultivation of Hemp: Botany, Varieties, Cultivation, and Harvesting (Hemptech, 1998). Dr. Bocsa is an eminent Hungarian hemp seed breeder who has experimented with many hybrid varieties in searching for higher yields.
Hemp is a tall, vigorous annual whose surface is covered with top or glandular hairs that stand up in the beginning, but soon lie down. The hard stalk is hexagonally-shaped and its surface is often vertically ribbed, especially when the plants are widely spaced. The hemp plant produces more pollen than any other cultured plant and is often cross-pollinated by the wind, since pollen can travel long distances.
Currently available hemp seed has to be imported from a very limited selection of breeding programs in France, Hungary, the Netherlands, Ukraine, Russia, and Yugoslavia. As of 1996, the French may have inadvertently been given the monopoly because of EU regulations that specify a THC threshold of 0.3%.
One of the main reasons for this stems from an argument used by the US, who states that Europe subsidizes its hemp growers. Why this is a problem is not clear since the US subsidizes its own food and animal producers.
European hemp growers are subsidized because their governments realize that hemp is an important rotational crop necessary for a more sustainable agricultural and economic system, whereas, the US has not come to that realization as yet. Furthermore, they still put growing fiber- and food-hemp into the same category as marijuana. According to the DEA’s own figures, 95 to 98 percent of the Cannabis plants destroyed each year are hemp plants and not marijuana.
- Hemp does not deplete the soil of nutrients, but rather nourishes it instead. From the USDA’s 1913 Yearbook: “Hemp cultivated for the production of fiber, cut before the seeds are formed, and retted on the land where it has been grown, tends to improve rather than injure the soil. It improves its physical condition, destroys weeds, and does not exhaust its fertility. Kentucky farmers commonly grew hemp in the same fields ten to fifteen years in a row, with the last year being just as productive as the initial one.”
- Its deep root system prevents soil erosion. Approximately 6 pounds of topsoil washes away into rivers and oceans for every pound of food produced in the United States alone.
- Hemp yields four times more fiber per acre than trees do. Although hemp can greatly reduce the need to cut down trees, it cannot replace forests. Both are needed. Forests worldwide are being cut down at a faster rate than they can regrow, including ancient forests whose gifts cannot be recovered.
- Hemp absorbs heavy-metal contamination from the air and the soil and can help clean up both if hemp were allowed to be planted in the US. While certain toxic pesticides are banned in the US, they are still being sold to other countries by American companies. Then, these very same chemicals are returned to the American food supply on imports that have been sprayed with these banned chemicals.
- With growth averaging 15 feet in 100 days, hemp provides its own mulch, shades out weeds, and reduces or eliminates the use of costly herbicides. After which, the field is virtually weed-free, nourished, and ready for the next crop. Because of this enrichment, farmers report an increase in yields and size of crops grown after a planting of hemp.
- Hemp improves water quality of an area. Huge underground aquifers – the only source of fresh water in some regions – are being depleted in China, India, the Mideast, the United States, and elsewhere at a faster rate than people realize. What is left, is rapidly becoming polluted. Amphibians, the bellwethers of air and water quality, are disappearing from their habitats all over the globe.
- Hemp provides 8 times the tensile strength and 4 times the durability of cotton. Although it wrinkles like linen, it also breathes like it, too.
- Hemp crops are more versatile than soybeans, cotton, and the Douglas fir combined. Its products are also just as interchangeable with those made from cotton, timber, and petroleum.
- Altitude:
Seed hemp should not be grown at altitudes higher than 200-250 m (650-800 feet) above sea level. Any higher and there is no guarantee that even early varieties will mature.
- Day/Night Length:
The reproductive phase of hemp is regulated by the length of the day and nights, depending on the variety. Longer nights encourage earlier maturation, but timing will vary from one cultivar to another.
Hemp’s short-day cycle causes the plant to move from the vegetative to the generative phase only if the daily exposure to sunlight is shorter than a specific maximum required. Therefore, early plantings produce more mass for fiber, maturing more quickly as the days shorten in the summer and fall. Thus, early growth is important. For seed production, later plantings may reduce stem length and mass. - Latitude:
It is wise for prospective growers to consult a map to determine the latitude where the seed was produced.
- If the latitude of the seed’s origin was closer to the Earth’s pole from where it will be planted; that is, north for Northern Hemisphere growers and south for Southern Hemisphere growers, then fiber yields will be low. Therefore, growers need to consider raising the crop for seed and taking the stalks as a byproduct.
- If the seed originated at a latitude closer to the equator than where it will be grown then the crop will flower later and should be grown for fiber. It should also be cut as the male plants begin to shed pollen.
- Planting any hemp seed closer to the equator than its usual cultivation area will accelerate flowering and planting closer toward one of the Earth’s poles will delay flowering. This is because during the growing season, in either hemisphere, the hours of darkness diminish as the pole is approached.
- Although hemp can be grown in almost any climate, it is risky to take seeds adapted to a certain geographic area and plant them in a different region. Hemp seeds need time to adjust to local variations in climate, soil chemistry, predation, and so on. For instance, Chilean hemp was grown in North America to extend supplies during WWII; but it performed very poorly in Wisconsin and Iowa despite the similar latitudes of these states and Chile. Normally, it takes 3 to 10 years for hemp plants to adapt to an area. Ultimately, there is no substitute for regional breeding and one year’s data is not sufficient for drawing valid conclusions.
- Cultivation of southern dioecious varieties for seeds is not recommended because of its small seed yields and the uncertainty of maturation. In general, wine-growing regions are also excellent for hempseed cultivation.
- Nutrients:
Traditionally, it has been grown in rotation with corn; and its nutritive requirements are similar. Hemp is often used to prepare the soil for such other small grains as wheat, and such multi-season legumes as alfalfa or clover. Suggested rates of the three most important nutrients are: 120kg/ha of nitrogen; 100 kg/ha of phosphorus; and 160 kg/ha of potassium.
Other macro and micro nutrients are also needed. Much of this nutrient draw is returned to the soil (up to 70%) as leaves fall off stalks during growth. Other ways nutrients are returned include the trimmings at harvest time and during the retting process if done in the field,and when roots remain in the soil.- Nitrogen is considered to be the most important nutrient. As soon as fiber hemp begins to grow, it requires large amounts. A yellowish-grey green color of the first true leaves on the seedlings indicates a lack of nitrogen and will severely reduce fiber mass. An adequate supply must be provided throughout the entire vegetative period in order to achieve high stalk yield. On the other hand, excessive amounts can be just as detrimental. The stalk will then become larger, the bark section thinner, and the fiber content and strength reduced.
- Phosphorus is necessary for proper development of fiber bundles, fiber cells, and stalk yields. Phosphorus contributes to the elasticity and tensile strength of the fiber cells and, ultimately, the fiber bundles. Hemp also needs it to utilize nitrogen effectively. This need increases from the point of germination to harvest and requires substantial amounts throughout its entire growing season.
- Potassium affects fiber quality to a greater extent than by phosphorus.
- Calcium and Magnesium are also required, but not given in specific quantities to one crop, but applied during crop rotation.
- Trace elements in hemp are necessary; but this has not yet been clarified, although preliminary investigations suggest positive results from leaf fertilization during dry periods.
- Soil:
- Hemp prefers well-drained loam soils, with a pH over 6.0, although 7.0-7.5 is preferred.
- Hemp is sensitive to soil compaction.
- Seed hemp prefers marshy soils.
- Spacing:
Seed hemp requires more space than fiber hemp, and should be tightly packed together. Although seed hemp develops considerably more slowly than fiber hemp, near the end of the vegetative period it begins to grow more rapidly until it becomes taller than fiber hemp with more branches to produce seeds. - Temperatures:
- Hemp plants prefer semi-humid conditions with temperatures between 14 and 27°C (57 and 80°F). However, seedlings and mature plants can endure a light frost of -5°C (28°F). Heat-stressed plants may not set seed well or at all.
- Seed hemp has different climatic requirements than that of fiber hemp and demands more heat because the vegetation period lasts 5-6 weeks longer.
- Water:
Despite claims, hemp does require large amounts of water – 30-40 cm (12-15 inches) of water per each growing season. A minimum of ten inches during the vegetative period (the first six weeks) to develop substantial stalk length is suggested. If this is met, growth has been measured to 12 inches in a week Although hemp is basically drought-resistant, in a few weeks mass will be reduced and maturity will be hastened.
- Yield:
An acre of hemp yields:
- between three and eight tons of dry stalk
- about 25% fiber, of which about half (or a little less than one-half ton) is long strand suitable for twine or cloth
- about 75% hurds which are used for paper pulp, fiber board, animal bedding, planting substrates, non-woven uses, biofilters, and isochanvre. (See an explanation here.). Hurds are 50% more absorbent than wood chips plus, they rapidly degrade in a compost heap.
- Chinamington:
One of the main problems for hemp growers worldwide is the lack of germ plasms that are adapted to all of the diverse areas. This is certainly true of North America, which once boasted having several superior varieties. These have not been preserved, however. The most famous was the Kentucky Hemp, which was primarily of Chinese origin and mixed with European lineages in Kentucky after 1850. In the 1920s several improved varieties were developed until the government terminated the programs in 1933.
One of these varieties was Chinamington, the highest-yielding hemp the world had yet seen and used as one-half of the first hybrid hemp developed in Hungary. Chinamington, and the entire Kentucky hemp lineage, appears to have been lost because the USDA did not maintain its entire seed stock held in the National Seed Storage Laboratory in Fort Collins, Colorado. Representatives of the lab say that the stock was discarded in the 1950s because hemp was no longer considered an important source of fiber. - Finola or FIN-314:
Finola is possibly the most important cultivar developed to date for use as a seed-producing crop. This non-GMO variety was developed by Dr. Jace Callaway, of Finland.
Finola is the first true grain variety of hemp and was developed from early-blooming Russian stock. It does not look much like the typical Cannabis plant and does not have a tendency to branch. Thus, it focuses its energy on producing a single stalk that is typically full of seeds. Over two metric tons of seed per hectare have been produced by this variety in Canada, which surpasses earlier records of hemp seed production by over 30%.
In addition to better looks and harvestability, Finola typically produces more oil (up to 30% more) and protein (up to 28% more) than other hemp varieties. The fatty acid profile of Finola oil has over 90% unsaturated fats, with over 4% GLA and nearly 2% SDA. Despite having smaller seeds than most other hemp seed varieties, Finola seeds are sweeter, containing up to 5% natural sugars. Fresh Finola oil has a peppery-citrus flavor. (Throughout Europe, Finola seed and seed by-products are available only through Finola.)
All this said, hemp is still a relatively easy crop to grow, and growers need only follow a few established guidelines to have a successful crop.
Advantages
General Requirements
-
Although hemp (seed or fiber) is a very resilient plant and used for crop rotation, it should not be grown in the same location for more than two successive years, otherwise the hemp flea, as well as the hemp moth, multiply rapidly. (See more on hemp pests separately.)
Stalk height is dependent on a number of factors, with the most important being the amount of daily exposure to the sun, the variety (geographical race), the soil conditions, availability of nuttrients, sufficient water supply, spacing of the plants, and finally, the sex of the plant.
