What Does It Take To Grow Hemp?

Hemp, which refers to strains of Cannabis that lack enough THC to get you high, but have a long history of use in products ranging from food and cosmetics to textiles and building materials, is one of the oldest cultivated crops on Earth, and featured prominently on colonial era farms in the U.S.

There are several great reasons for using hemp as an industrial crop. It enjoys vigorous growth with deep tap roots and lengthy, lanky stalks. The type of hemp you choose will dictate the amount of fiber and seeds, which may mean a difference in oil composition. Overall, you can expect your hemp crop to be ready for harvest in approximately four months.

The stalks of hemp are harvested for their fiber, which is used to create a variety of textile materials including newspaper. Did you know that hemp produces four times the yield of paper per acre than trees? As it only takes months to harvest, as opposed to years when growing trees, it makes perfect sense to use hemp to supply the world with paper.

Hemp seeds are usually used to create food such as bread, milk, ice cream, granola, and protein powder. You can also use oil from the seeds to make salad dressings, fatty acid supplements, and cooking oils. Hemp seed oil has even been used as a biofuel diesel alternative.

Other benefits of hemp include the fact it is resistant to pests, has dense growth which means weeds seldom get a look in, has deep tap roots which protect soil, and it is far easier to farm organically than the majority of fibrous crops. Unfortunately, hemp was grouped with cannabis when the government decided to make the plant federally illegal. There is a suggestion that William Randolph Hearst, with the aid of a major company that used trees to make paper, helped Harry Anslinger in his quest to outlaw the herb in 1937.

Why Grow Hemp?

Hemp grows more vigorously than corn, but requires less water, pesticides, herbicides, and fertilizer, earning it a reputation as a sustainable crop. The plant has over 25,000 known uses and is potentially an eco-friendly alternative for other crops commonly produced on an industrial scale.

The voluminous quantities of biomass hemp produces are a potential raw material for livestock feed, biofuel production, paper and textiles. The seeds, and the oil produced from them, have many uses, both culinary and industrial. It’s even possible to make alternative building materials with the stalks, such as hempcrete, which sequesters more carbon from the atmosphere than the carbon emissions required to produce it.

One of the most lucrative industries that hemp farmers are tapping into is the production of CBD oil, a medicinal compound in cannabis plants that contains no THC and is thus legal to consume in all 50 states.

A recent Cornell University analysis found that profits ranged from roughly $130 to $730 per acre – comparable to most grain crops on the lower end and approaching high-value vegetable crops on the upper end.

The list of benefits associated with hemp production is extensive. Some examples include:

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  • Dense growth leaves little room for competing weeds
  • Highly pest-resistant
  • Deep tap roots help to protect soil
  • Easier to farm organically than most other fibrous crops

How to Grow Industrial Hemp?

Choose the right genetics

Remember, industrial hemp is an excellent agricultural crop which you can harvest for its stalks and seeds. Therefore, you need to take genetics into account depending on what part of the plant you want to focus on. For example, you may want the seeds to create CBD oil or stalks for textiles.

In the modern era, most farmers are growing hemp for CBD extraction. If you want hemp for seed and fiber to make food and clothes, European strains such as Carmaleonte or Fibranova from Italy are ideal.

Grow in the Right Climate

Industrial hemp is an agricultural crop that can thrive in many environments. Its deep tap roots can find water sequestered in the ground, but for a healthy hemp crop, it will need additional water via rainfall or watering.

The soil quality should lean on the alkaline side. A pH level above 6 is necessary, but a reading between 7 to 7.5 is ideal. Even if healthy soil is impossible to provide, hemp plants often find a way to manage regardless. Season after season, hemp roots will aerate the soil to improve its quality.

Finally, industrial hemp should not be grown indoors. This plant is meant to be grown on a large scale for low costs, and by growing inside, your costs will far exceed the monetary value of your yield.

The best time to seed hemp depends on the soil conditions and weather. Savvy hemp growers know that they can’t necessarily point to a calendar and say “this is the day I will start growing hemp.” You can seed hemp up to two weeks prior to corn as long as the soil conditions are right.
Don’t try to seed hemp until the temperature of the soil is at least 46 degrees Fahrenheit. Remember, your hemp seeds will germinate in 1-2 days, and emerge in 5-7 days when the moisture and temperature are at the right levels. When growing for fiber, seed it as soon as you can. When growing for grain, seed later to reduce the stalk’s overall height.

Overall, make sure your hemp is growing outdoors in a mild climate with a humid atmosphere. Rainfall should be 25-30 inches per annum to aid good soil moisture.

Soil quality

The pH of the soil used when growing hemp is very different to that used for marijuana. While cannabis strains prefer a slightly acidic soil with a pH between 6.0 and 6.8, hemp plants prefer a marginally alkaline soil of 7.0 to 7.5. Ideally, the soil will possess good moisture and nutrient holding capacity.

We advise against badly drained soils because the excess surface water after heavy rainfall will cause damage to your crop. Hemp plants are very sensitive to flooding and soil compaction. If you can, use a fine, firm seedbed as it results in uniform germination of the seeds. If you place seeds at a depth of more than two inches, seedlings will not emerge uniformly.

If you find it impossible to provide excellent soil, your hemp plants may still thrive because they improve the quality of soil by aerating it every season.

Achieving the right plant density

If you have grown cannabis before, it is time to forget everything you ever knew about plant population. With marijuana strains, you are supposed to keep them apart. When it comes to growing hemp, however, you need to plant the seeds as close together as possible. The perfect hemp field consists of thousands of plants comprised of a single stalk. In other words, you want it to look like a cornfield!

For instance, you can benefit from enormous yields of premium quality fiber when you achieve the ideal density. Experts recommend opting for a seeding rate of anywhere between 250 and 400 viable seeds per square meter. This equates to an incredible 50-60 pounds of hemp per acre, although this amount depends on factors such as soil fertility and type.

If you are growing hemp for grain, a lower seeding rate of up to 45 pounds per acre is better. When the density is as low as 20 pounds per acre, you are risking weed infestation.

Feeding your hemp

As a rule of thumb, make twice as many nutrients available to your crop as will be removed from the soil at harvest time. As hemp produces an exceptional amount of plant material in a short vegetative period, it requires LOTS of feeding. In the first 6-8 weeks, make sure your hemp plants receive plenty of nitrogen. Although you also need potassium and phosphorus during the vegetative phase, they are more important during seed formation and flowering.

The following numbers are NOT set in stone but should give you an idea of the amount of nutrients required:

  • 80-100 pounds of Nitrogen per acre.
  • 35-50 pounds of Phosphate per acre.
  • 52-70 pounds of Potassium per acre.

When to harvest your hemp

When harvesting for high-quality fiber, you need to get to work after the final pollen has been shed. If you’re harvesting for seed, you’ll need to wait another 4-6 weeks when at least 60% of the seed has ripened. In general, you can expect your fiber hemp to be ready for harvest within 70 days of seeding, although it could take up to 90 days.

Harvesting seed hemp is a tricky business because seeds not only mature at different rates in different plants, but they mature at various times on the same plant! For instance, when the lower seeds near the stalk reach maturity, they are ahead of the seeds near the top which aren’t ready. Therefore, you have to think about harvesting at a time where you lose the smallest amount of seed.

Harvesting fiber hemp is a bit more straightforward because it is ready when the plant has finished producing pollen, and the first seeds begin to develop. However, the time when you harvest will dictate the variety and maturity of the fiber you want. For example, fiber becomes extremely coarse if you wait too long. Hemp is sensitive to light so early planting results in taller crops and an increased amount of fiber.

For grain, you can expect a yield of between 250 and 700 pounds per acre, although expert growers can achieve 1,800 pounds per acre! For fiber, the average yield is in the 0.75 to 2 ton per acre range, but experts can enjoy a yield of 5 tons per acre.

Should you use chemical defoliants?

It is impossible to remove the leaves from hemp by hand because the yield is far too large. However, you need to get rid of burdensome leaves because they take up too much space during transporting and retting. Chemical defoliation is a method of removing leaves and occurs when male plants are 10-15% into the flowering stage or 5-8 days before technical maturation.

One of the most popular chemical defoliants is Roundup, which contains 20% glyphosate. The problem with glyphosate is that you need to use enormous amounts in comparison to alternatives such as Basta. Also, you can’t use Roundup within 10 meters of a stream or lake because it is toxic to fish.

Purivel is another popular option, and it works by hindering chlorophyll synthesis, especially in new leaves. As a result, the leaves start drying out within 8 days and fall off within 12 days. Unfortunately, there are few alternatives to chemical defoliation. They include manual removal, water-retting or machine removal. None of them are viable alternatives for most enterprises in the United States. Over in Europe, companies are no longer using water retting which means they don’t need to use chemical defoliation at all.


The process of retting is a post-harvest necessity. The term ‘retting’ refers to a microbial decay of pectin, the substance responsible for gluing the fiber of hemp to its stem. You need retting if you wish to obtain the highest quality fibers. It is a tricky process because you are relying on the weather (because it is performed outdoors).

There five main types of retting:

  • Water retting: This involves bundling the stems together and submerging them in water. Bacteria will break down the pectin, and you should produce premium-grade fiber within 7-10 days.
  • Warm water retting: This process involves soaking bundles in water for 24 hours. At this stage, you use new water and add heat to warm the batch for the next 48-72 hours. When performed correctly, warm water retting produces a clean and uniform fiber.
  • Dew retting: This happens when the stalks are left out in the field to allow dew, rain or irrigation to keep the stems moist. It is a long, drawn-out process that can take up to five weeks, and you typically end up with a light brown coarse fiber.
  • Green retting: This is a completely mechanical process where the components are separated and used for paper, textiles, or fiberboard products.
  • Chemical retting: You use chemicals to dissolve the pectin which causes the components to be separated. It is a rapid-fire tactic because it takes just 48 hours to work. You are left with a high-quality product. The downside is the environmental impact.

What Are the Biggest Obstacles When Growing Hemp?

Hemp is often attributed with miraculous potential for sequestering carbon, reducing agricultural pollution, and allowing farmers to make large profits on marginal land. But the reality is not so simple. Here are some things to keep in mind before deciding if hemp is the right crop for you.

You need a lot of land: This is a crop suited for industrial applications, not farmer’s market sales. As with most grains, it’s tough to be profitable growing hemp without planting at least 50 acres or so.

The “red-tape quotient” is high: Because of its legal limbo, hemp growers need special licenses from their state, which means fees and paperwork. Growers may also be subject to a criminal background check. In states where it is legal, farmers must have their hemp plants tested to ensure they are below a certain threshold of THC content. If your plants are found to have too much THC, they may be destroyed.

Suitable seed can be hard to find: Hemp growers are generally required to plant seed that has been certified for low THC content, but the seed industry lags behind the demand and there are potential complications with the feds when shipping cannabis seeds across state lines.

Hemp is an ideal plant for organic farmers because it requires minimal inputs, is fairly resistant to pests and diseases, and grow so fast and tall that it outcompetes weeds, minimizing the need for hand cultivation – a major labor cost for most other organic crops.

The USDA does not allow marijuana to be certified organic in the states where it is legally grown, but the agency has made an exemption for hemp. The market for certified organic hemp seeds, a popular health food, is especially strong. For thousands of years, hemp was used around the world, and when cannabis became illegal, hemp suffered heavily as a result. We can only hope that as cannabis laws loosen, so will those around this sustainable crop.

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