Hemp, for all intents and purposes, is just another variant of Cannabis sativa. What distinguishes hemp from other cannabis is its THC content. By most definitions, hemp produces less than 0.3% THC. Some states define hemp as any cultivar with less than 1% THC, but international standards go with 0.3%.
Currently, 14 U.S. states permit hemp farming. In 2014, President Obama signed a federal farm bill that allows hemp cultivation if states say it’s OK. Most of these states restrict grows to purely agricultural or research purposes. But in coming years, we may be seeing more large scale commercial grows for hemp.
Hemp is still technically defined as a Schedule I controlled substance, as is cannabis. Recently, the FDA claimed that hemp can be grown only for agricultural purposes—such as for fiber and food—but that statement isn’t a law and hasn’t been challenged in court.
Because hemp contains practically no THC, it lacks a psychoactive effect. Hemp, however, can still produce other beneficial cannabinoids, especially CBD (which offers many of the same medicinal properties as THC). But because it’s not psychoactive, CBD is ideal for patients who want to be medicated without feeling medicated. This is one of hemp’s most viable commercial attributes. In Colorado, hemp is grown almost exclusively for its CBD.
Hemp offers many other uses. Its fiber can be used to make paper, textiles and construction material. Biofuels can be made from hemp. Hempcrete, a type of concrete made with hemp stalks, is incredibly durable and lightweight. Hempcrete can absorb carbon dioxide from the air, reducing a building’s overall carbon footprint.
And you’ve probably seen hemp seeds in grocery stores. These are packed with Omega-3 fatty acids, proteins and amino acids, all of which are necessary for health.
Cultivating hemp offers many benefits for the professional grower. First, many states that allow hemp permit it to be grown outdoors, since there’s no fear of black marketers stealing the plants. On the contrary, cannabis with greater than 0.3% THC must be grown in locked buildings that can’t be seen by the public.
When hemp is cultivated outdoors, farmers can use sunlight to feed their plants. This cuts the costs of buying expensive lights and ballasts and running up electricity bills. And with the right climate, farmers can rely on rainwater rather than the municipal water supply—again, saving on costs.
Although every plant can make use of nitrogenous fertilizers, hemp doesn’t need a lot of them. One study from Europe showed that while nitrogen boosted hemp yields, it didn’t do it by much. For growers, this means you can focus on other methods to maximize yields than dumping a lot of money into synthetic products.
When growing hemp on a large scale, you’ll probably want to use a combine rather than harvesting by hand. According to Ben Holmes, a hemp breeder and owner of Centennial Seeds in Lafayette, Colo., cannabis rich in THC tend to be “high resin” strains.
That resin is a black, goopy mass with the consistency of tar. High resin plants will gunk up a combine during harvest. Cleaning it out requires hours or days of scraping. But low resin strains (like industrial hemp), which Holmes calls “dry varieties,” won’t harm the combine.
Industrial hemp thrives in slightly alkaline soils, just above the pH 7 range. Seeds should be planted around 2 to 3 cm deep—and up to 6 cm deep in more volatile climates, such as in areas with high winds and heavy rains.
Hemp grows best in aerated loam soil. If your soil is loaded with clay, you might want to rethink it (hemp doesn’t grow very well in clay). You’ll also want ample rainfall, especially in the first two months. If your area doesn’t get a lot of rain, you’ll need to set up a watering schedule that keeps the soil fairly moist during those first two months.
According to Purdue University’s Horticulture Department, it’s also good to get your soil analyzed for proper nutrients. Purdue’s hemp farming website states, “Organic matter is preferably over 3.5%, phosphorus should be medium to high (>40 ppm), potassium should be medium to high (>250 ppm), sulfur good (>5,000 ppm), and calcium not in excess (<6,000 ppm).” If your soil doesn’t meet these requirements, you may need to add nutrients.
And most important, hemp needs warmth to thrive. If you’re growing outdoors, this will limit you to the spring/summer seasons, with a harvest in the fall. Hemp can be planted as a monocrop, but consider rotations with other crops every three to four years to keep the soil healthy.
Check with your state’s regulations to make sure you’re growing hemp within their guidelines. For example, many states require a license from the agricultural department.
You’re also consenting to random field tests of your grow. The state may send its inspectors to your farm to take samples of your crop and determine if you’re under the THC limit. If your crop tests higher than the limit, it’s “hot”—and the state can order you to destroy the entire crop. Or, in some states (such as Colorado), the hemp can be processed for onsite use but can’t be sold.
Fortunately, as more of us breed and cultivate hemp, we’re getting more reliable seeds. These seeds consistently produce hemp that tests under 0.3% THC.
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