8 Tips for Growing Industrial Hemp

Everything you need to know to get from from seed to harvest
MarijuanaBreak Staff / Updated on December 4, 2018

Growing Industrial Hemp

It is easy to get confused between marijuana and hemp. While they both come from the cannabis plant, they utilize different parts of it and are grown using different methods. If you’ve ever grown marijuana with the goal of producing a high-THC yield, you know that you’re harvesting the plant for the cannabinoid-laden flowers. With industrial hemp, the focus is on the leaves and stalks.

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.

Hopefully, the proposed Hemp Farming Act will be voted into law as it will remove hemp from the list of Schedule I controlled substances, and ensure it becomes a regular agricultural commodity. In this growing guide, we provide you with eight tips for growing industrial hemp, a low-cost, sustainable crop.

1 – 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.

If you’re looking to extract CBD from hemp, it is better to look at American grown strains. While most European strains seldom have more than 5% CBD, American genomic research and selective breeding mean there are strains with up to 20% CBD. Check out the likes of Otto II, Cherry, and BaOx, all of which grow in Colorado and are used to the tough Rocky Mountain climate.

2 – Climate considerations

Industrial hemp is a sturdy and durable crop capable of growing in a variety of environments. As it has deep tap roots, it can locate hard-to-find water. Even so, you need to water regularly to top it up. Unfortunately, industrial hemp is not suitable for an indoor grower. This is because it is supposed to be grown on a massive ‘industrial’ scale to reduce overall costs and boost profit margin. If you try to grow hemp indoors, you will be subject to enormous costs which you have no chance of exceeding with the value of the 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.

3 – 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.

4 – 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.

5 – 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.

6 – 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.

7 – 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.

8 – Retting

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.

One final point: Make sure the moisture content of your hemp stalks does not exceed 15% during storage. You can cover the bales of hemp for several months as long as they are stored in a dry place. Good storage location options include barns and sheds.

8 Tips for Growing Industrial Hemp
December 4, 2018

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