combine for stripping hemp

Creating a Reliable Hemp Harvester: An International Mission

Hemp, including that grown for its CBD-rich flowers, has strong and resilient stalks. While that strength is a plus for hemp’s industrial uses, it can create issues at harvest for cultivators seeking to produce high-CBD smokable flower or biomass for processing. A Pennsylvania hemp grower told Hemp Benchmarks in the summer of 2019, “I’ve personally burned up three combines in the last three-and-a-half to five years, processing ripe material.”

Farmers seeking to preserve hemp flowers to sell as a smokable product typically need to hire manual labor to hand-harvest their plants. Hand-cutting is especially important to protect not only the flowers, but also their trichomes: small, sticky, glandular outgrowths that cover hemp flowers and contain much of the plant’s cannabinoids and terpenes.

Meanwhile, many of those growing high-CBD varieties for processing into extracts and other products have taken to grinding up entire plants – flowers, leaves, stalks, and all. Although more efficient than hand-harvesting, this practice lowers the cannabinoid potency of the resulting biomass.

Both approaches are necessitated by the lack of specialized hemp harvesting equipment available currently, and neither is ideal. Our Hemp Benchmarks price assessments have shown that smokable CBD flower typically fetches significantly higher per-pound prices compared to CBD biomass, but hand-harvesting is expensive and time-consuming. Biomass producers, on the other hand, could demand higher prices for their crops if they could easily separate the cannabinoid-rich flowers and surrounding leaves from fan leaves and stalks.

Technology may now be catching up to the painstaking task of harvesting CBD-rich hemp. Agricultural engineers in the U.S. and Europe have recently debuted practicable mechanical hemp harvesters that can reportedly handle hemp flower safely, and in a quick and cost-efficient manner.

Working with Existing Combines

In Nebraska, a small company has created hemp harvesting technology for the plant’s flowers, seed, and stalks. FarmMax was started by a pair of brothers, Ty and Jay Stukenholtz, who were later joined in the business by Ty’s wife, Beth. The brothers both studied agricultural engineering at the University of Nebraska. Previously, they designed harvesting equipment for specialized seed companies, as well as for firms harvesting corn cobs for biofuels and biochemicals.

Starting five years ago, Ty told Hemp Benchmarks, the company worked to “understand the physiology of the [hemp] plant” while coming up with a hemp harvester that would make such work easier, faster, and more efficient for farmers. Working with a grant they received last year from Nebraska’s Department of Economic Development, the Stukenholtzes designed the Interceptor hemp harvester. The device, which became available in May, attaches to existing mass-produced combines and is currently designed to work with John Deere S Series models.

According to Ty, the Interceptor uses the mechanisms inside those combines to capture and separate the hemp flower – as well as the flower’s trichome-rich dust – from the plant’s seed and stem. “Because the flower material has such fine dust in it, it’s designed to collect that,” he said, “whereas a normal combine, you’d tend to blow out the flower material and you can’t with the Interceptor. The stem is basically thrashed and put back on the ground.”

Stukenholtz said that since the Interceptor is designed for farms with combines, it is not necessarily a good fit for smaller hemp cultivators. The company is preparing to sell its first Interceptor in the next several weeks, for use in the upcoming harvest. They have also been getting calls from hemp cultivators in Colorado, Montana, Illinois, and Canada.

From Europe, Innovations for Small Farmers

In Europe – where hemp farming has been ongoing for longer than in the U.S., but has traditionally focused primarily on industrial uses – there is significant competition for new technologies that assist cultivators with their work, especially as interest in CBD grows. In June, the European Industrial Hemp Association (EIHA) announced Henry’s Hemp Harvester, a German company, as the winner of its ‘Hemp Product of the Year 2020’ innovation award.

Company CEO Heinrich Wieker said his harvester was the result of four years of research, development, and production. The critical difference between hemp and other crops, he said, is its fiber. “It is so strong that it easily blocks large machines and [it is important] to avoid any rotating parts near the stems,” Wieker wrote in an email to Hemp Benchmarks. “My main focus at the harvest [was] always the flowers and I figured out a technique to imitate the hand-strip-move with thumbnail and index-finger.”

As described in the EIHA press release, Henry’s hemp harvester is a “double-module front-loaded attachment for harvesting industrial hemp flowers and stems,” and is especially designed for small farms. The company website, meanwhile, says a patented mechanism “gently strips the plant’s flowers and severs the stems in one pass,” allowing a harvesting rate of 1.2 acres (0.5 hectares) per hour. The harvester uses aluminum parts for weight reduction and can be driven by a small tractor.

Wieker said the first four of his machines will be delivered to European customers this summer. In the interim he is looking for a North American partner, with plans to have his machines on sale in the U.S. and Canada next year. His harvester, he added, creates an opportunity for “beginners, expanders and [those trying] to harvest hemp flowers efficiently with an affordable machine. I see a big potential at small hemp farms. They passionately create a diversity of beautiful products, adapt to the market and contribute a lot to the popularity and the acceptance of hemp.”

Henry’s Hemp Harvester – Various Configurations

Agricultural engineers in the U.S. and Europe have recently debuted practicable mechanical hemp harvesters that can reportedly handle hemp flower safely, and in a quick and cost-efficient manner.




New West Genetics partners with experienced farmers to produce hemp grain and high CBD flower using NWG’s proprietary genetics. We work closely to develop strong, mutually beneficial partnerships where risk is shared appropriately. Our partnerships are built on high standards with clear expectations for both parties: high-performing genetics and agronomy consultation by NWG; and our farmer partners provide extraordinary agronomic execution with no pesticide applications.

Past growers have come with an innovative mindset and a deep understanding of their production system including, among other important considerations, historical weather trends, the characteristics of their local soils and access to relevant equipment and machinery. We enter into partnerships with the intent to share our collective knowledge in order to continually improve and bring the best products to market.


Hemp is produced for grain, fiber and cannabinoids. Each has its own unique production requirements in order to create a quality product. Production of grain and fiber has been done commercially using modern agricultural methods for decades. Production of cannabinoids (e.g. flower) is in its infancy and many different approaches are being tested today. As a genetics provider, it is imperative that we breed cultivars suited to the standard method(s) of production so we are monitoring developments in this area very closely. The following is a summary of the state of production with recommendations where relevant.



Hemp grain production is performed similar to many other species of row crop and the general agronomic practices are quite well established.

Production for grain can be planted in late spring (May to June) on 8-16” rows using a traditional grain drill. The recommended seeding rate is

500,000 seeds per acre. Seed size is variable across cultivars so planting seed mass ranges from 18 to 30 pounds per acre. Stand establishments are most successful when planted 0.5”-1.0” deep into warm (>50⁰F) soils with good moisture. The soil should remain moist for the first 7-10 days after seeding. This is a critical step; soil moisture may be too low for good hemp germination but sufficient for germination of weedy species. There are currently no herbicides labeled for hemp in the US so good stand establishment resulting in a competitive crop are the best form of weed control.

Fertilize similar to a winter wheat crop:
Nitrogen, 50-100 lbs/ac; Phosphorus, 30-60 lbs/ac; Potassium, 50-80 lbs/ac

Harvest Management
Grain hemp is most often straight-cut while the plant is still a little green in order to minimize stem fiber wrapping. It can be threshed anywhere from 12% to 20% moisture. Harvested grain should be dried to 8% moisture immediately and may best be done with heated air, depending on geography and weather. Reduce auger speeds and use larger diameter augers or belt conveyors when moving hemp grain.

Recommendations for producing ELITE TM can be found here

A good video overview of production:

A good video of straight-cutting:


This area of hemp production agronomy has the lowest level of optimization – many different approaches are being explored at this point. This is not surprising since the CBD market has only become mainstream in the last 5 years, following legalization of hemp production. Many of the agronomic practices for flower production are similar to grain production so we refer you back to the GRAIN section for topics such as planting date, fertility and weed management. The two issues of debate today are: 1) planting method which will depend on the planting stock chosen (feminized seed, dioecious seed, clones, etc.); and 2) harvest method which is also impacted by the planting stock. We address each below.

Planting Stock
Much of the production today is done using clones or feminized seed with the end goal of fields containing only female plants. This is an intuitive approach since the female reproductive tissue (e.g. the buds) produces the valuable cannabinoids, and both approaches can control gender if they are done correctly. It also serves the purpose of eliminating, or at least minimizing, seed production, which is perceived as important by many flower producers. The all-female production method comes with some notable tradeoffs:

  1. High cost: clones and feminized seed are expensive to produce since this work in its entirety or partially conducted in greenhouses and requires intensive management practices (See FAQs: What is Feminized Seed?). This creates high economic risk for crop failure due to uncontrollable environmental factors such as hail or disease. It has also has led producers to plant at lower densities, ranging from 2,000 to 5,000 plants/acre in order to maximize the total yield per plant. These lower planting densities create the next tradeoff, weed control.
  2. Poor weed control: as mentioned above, commercial grain production is typically planted at a density of 500,000 plants per acres so that each acre of a dioecious cultivar contains around 250,000 female plants. In other words, about 100 times more than an all-female field! This density follows traditional agronomy theory which seeks to minimize bare ground in order to control weeds more effectively. The low density of all-female production necessitates high weed control costs or a tolerance of a high weed seed bank in the following years.
  3. Male pollen is difficult to control: hemp pollen is small and can be carried by wind for many miles (Small and Antle, 2003). This puts all-female hemp crops at risk of being pollinated by unknown fields with males, thus making the high input costs dubious. Further, most feminized seed providers do not guarantee 100% female seeds in their seed lots so walking fields to remove the rogue male is common practice and adds another production cost. It also presents a risk because even a single male plant can create tens of millions of pollen grains (Small and Antle, 2003). This means a single male plant can produce a significant amount of seed.

How do I harvest flower most efficiently?
The answer to this question must be made with several considerations in mind. First, as with harvesting any product, the method must maximize harvest of the mass per unit area harvested. Second, it must minimize loss of the glandular trichomes which contain the highest cannabinoid concentrations (See FAQs: What do we know about cannabinoids?). Trichomes are small and fragile so their loss during harvest is a legitimate concern. Finally, the method must incorporate a step for effectively sorting seed from flower. Hemp seeds have no cannabinoids so if they are present in the flower, the cannabinoid content of the seed/flower mixture will decrease. The following are brief descriptions of the methods we have reviewed. NWG does not endorse any of these methods (yet!) We will continue to update this page with our own data as we complete our experiments.

  1. Head or whole plant harvest: the principle here is similar to straight cutting grain except that rather than threshing the head, it is harvested into a truck for indoor drying and threshing. By threshing indoors, more control can be applied to trichome loss by collection with vacuum system.
    a. A video of a head harvesting system: Watch Video
    b. A video of a whole-plant harvesting system: Watch Video
  2. Harvest with a combine: this will be similar to grain harvest except that the combine settings are modified. The specific settings are not well-established but the main changes include lowering fan speeds and removing sieves with the intent to minimize loss of product other than the stalk. In this case the flower or flower/seed bulk is augered into the grain bin and then moved indoors for drying and processing. The crop can be windrowed in dry climates to expedite drying but care must be taken to harvest the crop before it becomes too dry in order to minimize trichome loss.
    a. A video of flower harvest with a combine: Watch Video
  3. Stripper header: a stripper header is not a common implement on US farms but it has some practical benefits for harvesting a hemp field. It operates just as the name would imply, the header strips the flower (and grain if present) leaving the stalk remaining in the field.
    a. A video showing a stripper header harvesting wheat: Watch Video
    b. A brief video showing what a field might look like after harvest with a stripper header: Watch Video
  4. Silage bags: This approach is built upon the practice of wet preservation commonly used in fodder production. In short, a forage harvester is used to chop and collect the entirety of the hemp crop. This means that the stalk, stems, the leaves, the flower and any seed that may be present are all harvested. This is expected to lower the cannabinoid percentage considerably since stalks, stems, leaves and seeds are considerably lower in cannabinoid content than the flower. The chopped, wet biomass is then placed into silage bags and the air is removed. What is unclear is the quality of the final product. Watch Video


Our position is that dioecious cultivars optimized for cannabinoid production is the only economically feasible approach to scaling production of these valuable compounds. It is based on the power of seed multiplication that all large-acreage commodity crops have utilized to create planting seed cost effectively. We expect the harvest methods will continue to innovate and adjust to continually improve yield. Regardless of method, NWG will continue to create planting seed that provides the farmer with a true dual-purpose, de-risked, profitable crop.

Agronomic innovation and industrial hemp production methods to produce and harvest high quality hemp grain, hemp flower and hemp fiber.