how to harvest hemp for cbd oil

How to Harvest Hemp

This article was co-authored by Maggie Moran and by wikiHow staff writer, Hunter Rising. Maggie Moran is a Professional Gardener in Pennsylvania.

This article has been viewed 60,928 times.

Hemp is a versatile plant that can be harvested for plant fibers or for their nutritious seeds. Unfortunately, the fibers and seeds mature at different times throughout the season and cannot be harvested together in the same crop. Whichever product you plan on harvesting from hemp, just make sure growing it in your area is legal.

  • If you want stronger fibers, you can collect the coarse fibers from mature stalks.
  • Hemp fibers and seeds mature at different times and are challenging to harvest at the same time. Make a decision on what product you’d prefer to harvest from your plants.
  • Sickles are curved blades commonly used for harvesting grains and tall stalks. They can be purchased at a gardening store.
  • A sickle-bar is an attachment for a riding lawnmower or tractor with a row of blades to cut the stalks at the same height. Rent a sickle-bar from a specialty farm equipment store.
  • Moisture and microbes break down the chemical bonds that hold the stem together.
  • Retting will not occur at temperatures below 41 °F (5 °C) or above 104 °F (40 °C). [4] X Research source
  • Retting can also be done by submerging the stalks in water for 7 to 10 days.
  • Moisture meters used to measure water levels in plants can be purchased online or at gardening stores.
  • Decorticators are available to rent from farming equipment stores.
  • Use caution when operating heavy machinery to avoid injury.
  • In the United States, harvest usually occurs in early October.
  • Seeds on the same plant will mature at different times. While some of the lower seeds may be mature, seeds higher on the plant may not be ready yet. Watch your plant carefully to determine when to harvest your plant for maximum yield.
  • Keep the fallen leaves on the soil to compost for next growing season.
  • For larger commercial crops, use a combine with a dual-beam cutter.
  • A clean bed sheet also works if you don’t have a tarp.
  • Use a machine thresher for large crops.
  • Use an industrial winnower for commercial crops to save time and energy.
  • Point a fan at the buckets if the area you’re working in has poor air flow.
  • Hemp seeds in a dry storeroom will burst and become germ-infested.
  • Seeds can be stored in sacks if they have a moisture level less than 12%.

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  1. ↑http://innvista.com/health/foods/hemp/harvesting-hemp/
  2. ↑http://nationalhempassociation.org/hemp-harvesting/
  3. ↑http://nationalhempassociation.org/hemp-harvesting/
  4. ↑https://www.hempbasics.com/hhusb/hh3fiber.htm
  5. ↑https://www.hempgazette.com/industrial-hemp/hemp-fiber-production/
  6. ↑https://www.hempgazette.com/industrial-hemp/hemp-fiber-production/
  7. ↑http://innvista.com/health/foods/hemp/harvesting-hemp/
  8. ↑http://innvista.com/health/foods/hemp/harvesting-hemp/
  9. ↑http://innvista.com/health/foods/hemp/harvesting-hemp/
  1. ↑http://innvista.com/health/foods/hemp/harvesting-hemp/
  2. ↑https://www.hempbasics.com/hhusb/hh2cul.htm#HH212
  3. ↑http://innvista.com/health/foods/hemp/harvesting-hemp/

About This Article

The best time to harvest hemp fibers is when seeds start developing on your plants. If you only have a few plants, use a sickle to cut the stalks. Try to cut as close to the base of the plant as you can. If you have large amounts of crops, use a mower with a sickle-bar attachment. Once you cut the stalks, pile them in a field and leave them for 5 weeks to rot slightly so their stems start to break down. After that, you’ll want to dry the stalks in a cool, dry area with a moisture level under 15 percent. To break down the stalks, you’ll need a decorticator, which is a machine that helps break off the dried hemp stalk. For more tips from our Gardening co-author, including how to harvest hemp seeds, read on!

Hemp Biomass: A Step-by-Step Guide to Harvesting

Hemp Biomass is the remaining organic material (stalks & leaves) after the flowers and/or seeds have been harvested from the plant.

Biomass can be regarded as “waste” in conventional farming, but this is not the case with hemp. There are two methods for collecting hemp biomass, and each are dependent on your end goals.

For collection of oils, leaves, or for use as fuel, hemp biomass should be dried as effectively as possible before further processing.

For fibre, cloth, or cord production hemp biomass should be “retted.” This insures the fibrous strands that make up the stalk can further separate to make further processing more efficient.

Hemp leaves and stalks can be used to produce a wide variety of goods. Having a successful hemp harvest is key to the quality of theses goods. There are a few factors that are imperative to know, to get the most from your crop.

What We’ll Need to Harvest Hemp Biomass:

For CBD Biomass: Flower, Oils, Leaves or Fuel

  • Machete, scythe, or shears
  • Transportation Vehicle
  • Drying location
  • Storage location
  • Processing equipment (Oil press, container, etc.)

For Hemp Fibre Biomass

  • Machete, scythe or shears
  • Transportation Vehicle
  • Retting Location
  • Storage Location
  • Decorticator (fiber extraction machine)

The Hemp Biomass Harvest

Depending on your geographical location, this stage needs to be planned well before you sow your first seeds in the ground.

In North America, hemp harvest typically takes place in late-summer/early-fall. Natural weather patterns lead to hurricanes on the Atlantic and prime wildfire season on the Pacific. Timing is very important.

The size of your crop is directly related to the size of your harving team or equipment. If the crop is too large for the team of harvesters to cut and transport during the time of harvest, not only is man power wasted, but the risk of loss in the quality of your crop due to mold, mildew, and bacteria increases drastically.

Crop size = Harvesting style

The size of your crop should be based on the method of which you plan to harvest.

1-2 people

(by hand)

Size: 1 acre or less

I recommend starting with one acre or less for the first season. This allows you the freedom to test a manageable harvest and drying period. Starting slowly will also help you to understand the needs for harvesting hemp biomass. You will soon understand if you have the proper facilities for production.

4-6 people

(by hand)

Size: 2-4 acres

A hemp harvest of 2 acres is a perfectly balanced size. This could be done with as little as 2-4 people, but also allows for proper crop rotation through the year. One acre can grow the production crop while the other is rejuvenated. I recommend rejuvenating soil with a cover crop such as legumes, buckwheat, or alfalfa.

Combine Applications

5+ acres

Combines are very expensive to own and maintain, yet they cut harvesting time down to almost nothing. The mantantice cost, mechanical settings, and operation experience necessary for optimum harvest are a few factors to consider.

For larger applications, the additional expense may be worth the investment. Time is money, and harvesting hemp is no exception.

Once you have experience growing hemp at 2-4 acres, the combine is most effective way of growing your yield. Unless you are willing to hire a team of skilled, manual harvesters, a Combine is the only way to sucessfully harvest hemp in a short window of time.

If hemp is going to be cut with a combine then the correct conditions for cutting need to be assessed before hand.
The proper conditions to harvest hemp with a combine are:

    (50% or less)
  • temperatures (65-90°F)
  • wind (light wind)

[BONUS TIP] Be sure to check the following days forecast and ensure there is no precipitation. This will allow the hemp to dry out properly before being baled.

Harvesting hemp plants should be on days where there is no precipitation in the forecast. Ensure there is adequate time to move the harvest into storage for the next stage of processing prior to any precipitation.

When harvesting, plants should be cut 2-3cm from the soil with a machete, scythe, or shears and stacked in piles for easy transport. Once the field is cut, there are two options for the next stage: Drying or Retting.

Drying Hemp Biomass

Drying hemp can be done in a variety of ways. From the inside of a sterile lab facility, to the rafters of an open air barn, the major factor here is space and adequate air flow.

The quickest way to reduce the quality of your crop is retaining moisture. While moisture is your friend during the growing period, as soon as the stalk is cut down rid as much moisture from the stalk as possible. Otherwise, mold and mildew can grow rapidly and reduce the quality of your harvest. This will effect the quality of your finished product as well.

Some choose to hang the entire plant upside down like traditional tobacco. However, this can allow for moisture build-up near the center of the plant. Hanging can also lead to mold and mildew growth making the plant less than desirable for production.

Snipping each branch from the plant and hanging them individually, allows for not only a quicker drying process and results in less product loss.

Hanging can be done a variety of ways. Hemp is commonly hung by wedging the stalk/branch through traditional drying wires or clamps. These wires/clamps allow it to hang with adequate air flow (from a fan or breeze) to dry for 3-5 days.

The times the plant need to dry are solely based on temperature, plant size, and air flow. Some plants may take a little longer than others.

Retting Hemp Biomass

If you intend on using your hemp biomass for fibre, retting can help make the process more effective. Retting uses micro-organisms and moisture to break down the stalk separating the individual fibres from the remainder of the stalk. This can be done two ways.

Water Retting

This is the most common type of retting and is done by soaking the stalks in water. Soaking them in water causes the cellular membrane to swell, and allows for easy separation of the fibre. There are two methods for using water retting

  • Natural Water Retting
    • A tried and true method, done for centuries around the globe. Natural water retting involves submerging hemp stalks in a naturally occurring water source such as a stream, river, or pond. When using a natural water source, be sure to secure the bundles of stalks under the water with a weight assuring that they do not float back to the surface. This process normally takes 8-14 days depending on the mineral content of the water.
    • As the name suggests this method is done in controlled conditions, such as inside a container for 4-8 days. The process is faster and allows for another valuable post-harvest product, mineral dense water. This water can be poured back onto the field as liquid fertilizer, as long as no harsh chemicals were used on the crop during growth. If harsh chemicals were used then the water needs to be filtered before returning it to the soil.

    With either form of water retting, the biomass then needs to be dried for a few days (1-3) to begin a curing process that will allow for easier processing in the next stage.

    Dew Retting

    Dew retting is only appropriate for climates where water is sparse. After the hemp is cut, it is then laid flat on the ground, in rows allowing air flow around each stalk. The night will bring in moisture and then the day will bring warmth and light, promoting bacterial growth.

    This creates a moisture rich microclimate within each stalk that allows for a similar breakdown in the biomass creating equal separation. Though, it does take a while longer (2-4 weeks) and the quality of “dew retting” biomass has been know to be lower than “water retting.”

    Hemp Biomass Storage

    There are a number of ways to store hemp biomass and each depend on harvesting methods and end goals.

    With manual harvest methods dried hemp can be stored in everything from plastic garbage bags, plastic bins, or cotton/hemp sacks. Stored then in a covered low moisture barn or similar low moisture storage facility.

    For the combine farmer, once the hemp is cut it will be also need to dry out for a few days. To promote faster drying, try raking with a hay rake or tedder to arrange into biomass into rows.

    Once it is dry the hemp will be baled by an automatic baler and tractor. Hemp can be baled with any hay baler.
    It can be baled using square or round bales based on the storage option for each unique situation. The biggest focus here is to do everything to insure low moisture content in each bale, 15% or less.

    It is essential to reduce the moisture content. Not only for the prevention of rot and bacteria, but for another frightening reality. Bales can spontaneously combust due to the close proximity of the biological material and bacteria feeding within the bale.

    This is not hard to test and there are warning signs that are “tells” that the bales may be getting too warm. The most visible, is steam emission.

    If the ceiling or eaves of the barn/storage facility are showing signs of condensation, action will need to be taken. Call the fire department immediately. Bales should be tested and checked regularly with a probing thermometer.

    Another simple way to test the internal temperature of the bales is to insert a iron rod as far into and as close to the center of the bale as possible. Remove the rod after two hours and feel the temperature of the metal.

    If it is too hot to handle easily, then the temperatures have increased above 120°F and action should be taken. Although bale storage does require additional maintenance, it is manageable if hemp is cut under the right conditions and the moisture content is monitored throughout the process.

    Hemp Biomass Processing

    One of the most rewarding parts of the process is taking what you have grown for months and seeing the final product. With so many finished goods possibilities, each it unique in its own way.

    Fibre

    Processing fibre can be done by hand with protective gloves and a club or baton.

    Most processing of fibre is done using a “decorticator.” A decorticator is a machine used to strip the bark/skin off the hemp stalks.

    They range from manual hand-crank to automatic fully-electric. When selecting a decorticator, confirm that it has settings to process hemp.

    The dried biomass is run through the machine’s ridgid crank system breaking the hard outer shell/skin from the stalk and separating the fibres. Creating a workable product for production use.

    From here the dried biomass is ready to be stored until enough of the biomass has been harvested to allow for viable oil production. Decorticator can be also used to “shuck” the dried biomass, making oil production more organized and efficient.

    The dried leaves can now be removed from the stalk and stored for later tea use. The leaves can remain loose or tea filter bags can be purchased for individual servings.

    Fuels

    Now the biomass is dry it is able to burn burned for fuel in fire places, cast iron stoves, or thermoelectric generators.

    Industrial Hemp Production (Part I): Cultivation and Management

    The production of industrial hemp, grown for fiber, seed, and cannabidiol (CBD), has surged in recent years. More recently, the Agriculture Improvement Act of 2018 (2018 Farm Bill) authorized the production of hemp and removed hemp and hemp seeds from the Drug Enforcement Administration’s (DEA) schedule of Controlled Substances. However, producers continue to face challenges in production and marketing of products because of constantly morphing state and federal regulations, typically revolving around total tetrahydrocannabinol (THC) levels within the plant, that affect both how crops are grown as well as the ability to harvest, sell, and process those products. THC is the main psychoactive compound that gives marijuana users their “high.” While marijuana cultivars typically contain 3% to 15% THC by weight, hemp cultivars are bred to contain only trace amounts (less than or equal to 0.3%).

    In addition to consumptive uses, alternative markets are also being explored. Hemp has been researched as a potential tool for phytoremediation and for potential biomass and energy production as both a biogas and solid fuel. Hemp fiber is being used for everything from plastic composites to car insulation. There have also been numerous studies on fiber quality, harvest times, flowering dates, and other basic production information. Therefore, it is important for growers to focus on what they want to cultivate most (fiber, grain, or flower), find the cultivars having the characteristics most desirable for that market, and understand production challenges and environmental constraints for their specific regions.

    The purpose of this article, Part I, is to give a basic overview of the different types of industrial hemp crops as well as agronomic considerations when growing those crops. Part II of the series will focus on integrated pest management and potential impacts on wildlife resources. Several additional articles will follow within this series and will be used to explore various issues along the entire supply chain, including production and marketing. Readers are encouraged to research regulations for industrial hemp production within their respective states as well as contact federal, state, and local agencies for additional information specific to their region.

    CBD/CBG Production

    Many of the newest hemp cultivars have been bred specifically for the CBD market and purposefully have higher CBD to THC ratios. CBD, one of numerous known cannabinoids, is reported to have many health benefits. Tinctures, lotions, edibles, and numerous other products – including the first and only clinically formulated and FDA-approved drug on the market for epilepsy (Epidiolex) – are created from CBD extracted from hemp flowers. Because CBD is extracted from glandular trichomes in unpollinated female hemp flowers, production involves asexual propagation (cuttings, transplants, clones) of female plants or the use of “feminized” seed. Male plants and their pollen are undesirable in a CBD hemp crop.

    Cannabigerol (CBG), a less-known cannabinoid, is considered a precursor to other cannabinoids and is currently gaining attention for possible use in pharmaceutical markets. Some health conditions for which CBG is being researched include inflammatory bowel disease, glaucoma, bladder problems, Huntington’s disease, colon cancer, and staph infections. Very little is known about the side effects of CBG oil or other forms of CBG, their long-term health effects, or interactions with other drugs. Therefore, more research is needed before widespread use can be expected.

    Hemp Fiber

    Hemp fiber, in contrast to cultivars grown for CBD, is used to create fabric, rope, insulation, bioplastics, and similar products (Pal and Lucia 2019, Mitchell and Uchanski 2020). Cultivars grown for this purpose are comprised of “bast” fibers (used for textiles, papers, insulation, and construction materials) and “hurd” fibers (commonly used for animal bedding, pulping, and concrete products) (Salentijn et al. 2015, Michell and Uchanski 2020). Once harvested, hemp must undergo a process known as “retting”, which begins breaking the chemical bonds that hold these two types of fibers together (Kaiser et al. 2015). This can be accomplished by leaving cut stalks in the field several weeks until rot sets in and fibers separate, but not so long as to result in deterioration of fiber quality. The process, of course, will be largely affected by local environmental conditions. Water retting is a more expensive, but reliable alternative in which stems are submerged for several days (Kaiser et al. 2015).

    Hemp Seed

    Hemp seeds are used in human food products, health supplements, personal hygiene products, lubricants, paints, solvents, hempseed oil (as distinct from CBD oil), and other products. As a dietary supplement for humans it contains a highly desirable ratio of omega-3 and omega-6 fatty acids compared to many other potential sources and is relatively high in both oil and protein contents (Williams and Mundell 2018). Hemp grain can be used to produce a wide array of consumer products including raw hemp hearts, toasted hemp seed, hemp seed oil, hemp flour, and even hemp coffee (ibid.). Oftentimes, dual-purpose industrial hemp crops are grown in which grain is harvested first followed by the stems for fiber production.

    Hemp seeds are combined/harvested when 70% of the seed is ripe (Kaiser et al. 2015). Harvesting grain past the optimal time generally results in lower quality seed, losses due to shattering, and possible bird damage. Seed should be dried to below 12% moisture for storage and from 8 to 10% for long-term storage.

    Cultivation

    In the world of industrial hemp production, the old axiom, “an ounce of prevention is worth a pound of cure”, certainly applies! Wind, hail, drought, pests, and other stressors can increase total THC levels in plants. If THC levels exceed the 0.3% threshold, producers are at risk of violating local, state, and federal laws and may be subject to fines and destruction of crops. Furthermore, there are currently no pesticides (insecticides, nematicides), herbicides, or fungicides labeled for use in industrial hemp crops in the U.S. This is true for both indoor and outdoor (field-scale) production systems (Williams and Mundell 2018). Therefore, good crop management and planning are essential to reduce those risks and improve the likelihood of a successful crop.

    Different varieties of industrial hemp respond very differently depending on latitude and basic agronomic inputs (Williams and Mundell 2018). In order to improve both yields and quality, industrial hemp should be planted on well-drained soils with high fertility, rich in organic matter. Soil pH should be at or slightly below neutral. A standard grain drill using either conventional tillage or no-till can be used if planting from seed and some moisture is needed to germinate or weeds will take over. An ideal seeding depth is ¼-inch, and plants germinate best in a firm bed (Kaiser et al. 2015). Recommended fertilizer applications range from 50 – 150 lbs/acre of nitrogen depending on a variety of factors; additional research is required before scientifically-based fertilizer recommendations for hemp production can be made.

    Spacing of plants, local environmental conditions, and crop type should be strongly considered prior to cultivation in order to reduce the risk of crop pests and disease. For CBD and/or seed oil production where branching and flowering is desirable, allowing for adequate air flow around the plant can reduce transmission of pests while reducing excessive moisture accumulation on leaves that might increase the chances for blights or spread of other fungi. Use of drip irrigation and appropriate plant spacing also reduces competition for water, sunlight and nutrients with neighboring plants. In contrast, hemp for fiber is planted in dense stands to promote taller height and discourage branching and flowering, thus maximizing fiber yields (Kaiser et al. 2015). Because of the challenges of registering hemp as an agricultural crop, the Environmental Protection Agency does not readily recognize pesticides (herbicides, insecticides, fungicides, nematicides, etc.) for hemp in the U.S, so growers must follow good cultural practices to reduce the impact of pests, especially weeds (see the next installment in this series: Part II – Integrated Pest Management).

    Knowing flowering times is critical for the production of hemp for CBD. When being grown as transplants, flowering can be initiated with even the slightest amount of root restriction. Most hemp cultivars will flower when exposed to day lengths of fewer than approximately 14 hours. Though farmers may be tempted to plant hemp early in the spring after the risk of frost has passed (i.e., April or May), especially in more southerly regions, hemp may begin to flower before the plants have had a chance to undergo any vegetative growth. Similarly, if growers plant too late in the season (late July), plants may flower prematurely (Kaiser et al. 2015, University of Georgia 2020). Therefore, planting date trials may be needed to determine the optimal planting time for hemp in a particular region. Auto-flowering cultivars exist that will initiate flowering a certain number of days after seeding, but they require nuances in production and they can be prone to stresses early in growth. Regular testing for THC during flowering is also recommended so producers can be sure to harvest their crop if THC levels begin to approach the legal threshold during flower maturation. Working with local agencies is critical to ensure regulations are followed.

    Stay tuned for the next article in the series coming soon: ““Integrated Pest Management and Implications for Wildlife,” by Dr. Susan Rupp.

    About the author: Dr. Susan Rupp is V.P. of the Land & Natural Resource Section at Lee Enterprises Consulting, the world’s premier bioeconomy consulting group, with more than 150 consultants and experts worldwide. The opinions expressed herein are those of the author and do not necessarily express the views of LEC.

    References

    Kaiser, C., C. Cassady, and M. Ernst. 2015. Industrial hemp production. University of Kentucky Cooperative Extension Service, University of Kentucky College of Agriculture, Food, and Environment.

    Mitchell, B. A., and M. E. Uchanski. 2020. Industrial hemp: reemergence of an alternative crop in the U.S. Fact Sheet 0.311. Colorado State University Extension. Fort Collins, Colorado.

    Pal, L. and L. Lucia. 2019. Renaissance of industrial hemp: a miracle crop for a multitude of products. BioResources 14(2):2460-2464.

    Salentijn, E.M.J., Q. Zhang, S. Amaducci, M. Yang, and L. M. Trindade. 2015. New developments in fiber hemp (Cannabis sativa L.) breeding. Ind. Crops Prod. 68:32-14.

    Williams, D. W. and R. Mundell. 2018. An introduction to industrial hemp and hemp agronomy. University of Kentucky College of Agriculture, Food and Environment, Cooperative Extension Service.