Midwestern Hemp Database: Utilizing Grower-Cooperator Networks to Assess Variety Performance of Industrial Hemp Across the North Central Region

Final report for ONC21-082

Project Type: Partnership
Funds awarded in 2021: $39,834.00
Projected End Date: 04/04/2023
Grant Recipient: University of Illinois Extension
Region: North Central
State: Illinois
Project Coordinator:
Chelsea Harbach, Ph.D.
University of Illinois Extension
Phillip Alberti
University of Wisconsin-Madison
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Project Information


Industrial hemp (Cannabis spp.) can be used to produce fiber, grain, and cannabinoids. A “new” crop to North Central agriculture, best management practices and performance of industrial hemp varieties have yet to be determined. Despite regional interest, a lack of university published resources regarding industrial hemp production and laboratory analysis exist.

To address these issues, our private-public partnership will use a multi-tiered approach to collect, analyze, and share data on variety performance and analytical methods throughout the NCR. Objectives of this program are 1). Grow the existing Midwestern Hemp Database by increasing the number of licensed hemp growers participating in the NCR; 2) Improve current data collection and visualization platforms for enhanced utility by stakeholders; 3) Establish a lab proficiency program among participating laboratories to evaluate analytical protocols across the region.

Data generated will improve the existing tool for growers to use when making seed company and variety decisions while providing transparency regarding laboratory protocols. Outreach is designed to expand existing regional partnerships, increase hemp production knowledge, and maximize economic and environmental sustainability of their production systems. A coordinated outreach plan, including the Midwestern Hemp Database website, written reports, conference presentations, and field days will facilitate the exchange of information.

Project Objectives:

Achievable objectives of the project include: 

  1. Grow the existing Midwestern Hemp Database to include at least 500 participating growers in 2023 across the NCR; this will be done by including additional states into the program with cooperation from their respective land grant institutions.    
  2. Select experienced grower-cooperators to conduct more stringent, but participatory, on-farm  trials using high potential varieties from prior research; data to be included in the Midwestern Hemp Database as "checks" to strengthen database. 
  3. Establish a proficiency program among participating laboratories to evaluate the various analytical methods being conducted in the region and how it may impact interstate commerce. 


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Materials and methods:

As a “new” crop to midwestern agriculture, best management practices (BMPs) and varietal performance of industrial hemp have yet to be determined. The BMPs yet to be developed include planting methods, variety performance, fertility requirements, rotational impacts, etc. Information from a needs-based assessment performed by hemp producers/processors showed that variety performance and cannabinoid development as the most pressing areas of research.

Obj 1) Grow the existing Midwestern Hemp Database (MHD) to include at least 500 participating growers in 2023

From 2020 through 2023, 286 hemp growers across the NCR contributed to the Midwestern Hemp Database. Crop management and variety performance data submitted by NCR hemp growers and variety trial participants were used to populate the MHD.  This public database provides timely data from commercial producers to support farmer decision-making.  Data is anonymized and aggregated to protect participants.  Specific protocols for agronomic data collection and floral sampling are distributed to participating growers who submit samples to partnering laboratories for analysis at a discounted rate. Using this approach, we can ensure the integrity of perhaps the most important and sensitive data for hemp growers: cannabinoid profiles. USDA sampling guidelines are followed and sent to participating, approved laboratories.

See attached Grower Protocol Midwestern Hemp Database

Obj 2) Recruit dedicated grower-cooperators to conduct participatory on-farm variety “checks” from 20+ NCR farms; data to be included in the Midwestern Hemp Database

Farmers will be involved in our project by conducting their own on-farm variety trials and contributing data to the Midwestern Hemp Database. Allowing growers to choose which verified varieties they want to grow allows them the freedom to experiment while contributing to a large data set at a discounted rate. Growers will also contribute further by sharing their experiences through outreach events and resources

To complement data being submitted by NCR hemp growers and strengthen the tool,  3+ growers per state will be recruited to conduct participatory on-farm variety “checks” including a consistent subset of high-potential varieties determined using results from 2020 university variety trials and data from the Midwestern Hemp Database. For on-farm trials, our team will supply seed/transplants/clones and cover the costs of cannabinoid testing. Growers will submit management, performance, and economic data via an online survey using the SeedLinked platform, as well as flower samples for cannabinoid analysis by partnering laboratories.  Grower data collection will emphasize experiential and qualitative information to complement the quantitative information generated by ongoing, coordinated university trials.  Participating growers will contribute to the development and delivery of outreach events and resources such as field days, conference presentations, and webinars.

See attached MHD Cultivar Check Program Grower Protocol

Research results and discussion:

Results from this trial show most high cannabinoid hemp grown in the Midwest will begin to flower mid-August to early September, continuing reproductive growth until harvest in late September/early October. Importantly, significant variation in flowering windows are observed for some cultivars, while others flower more uniformly, suggesting varying degrees of genetic uniformity within seed lots.


Flowering date was significantly impacted by cultivar and environment/ hardiness zone but no interactions were significant. Across all cultivars, the mean 50% flowering date at the midpoint of hardiness zones 5b/6a was day 231 or August 19th. Cultivars were subsequently grouped into maturity groups based on mean expected flowering day: Following August 20th (Late Maturing) or Prior to August 20th (Early Maturing).


Traditionally, photoperiodic flowering response due to geographic location has been discussed in terms of differences in latitude. For the purposes of this study, hardiness zones were used to reflect geographic location and correspond to the following approximate latitudes: Hardiness Zone 5a (~42- 45°),  Hardiness Zone 5b (~39- 42°), Hardiness Zone 6a (~38-39°), and Hardiness Zone 6b (~37-38°)


Across hardiness zones 5a (~37°) to 6b (~45°), average flowering date differed by ~7.9 days; this means that on average, cultivars experienced flowering initiation ~8 days later at the northern edge of hardiness zone 5a than they did in the southern edge of hardiness zone 6b. Growers may utilize this data to estimate approximate flowering dates based on their location relative to the average expected flowering dates observed. A similar delay in flowering date as hardiness zone decreases has also been observed when comparing the same cultivars evaluated in university station trials at Michigan, Wisconsin, and Illinois (see full report).


Agronomic performance ratings (germination, uniformity, overall performance etc.) are given as averages across all environments for each cultivar. These ratings were not analyzed for statistical significance given the subjective nature of the qualitative ratings and are meant to guide future research trials and cultivar selections only. In the same way, yield metrics across locations have historically been quite variable due to variance between and within cultivars and differences in grower-cooperator skill; for this reason, university station trials may be more useful/accurate sources of information for yield metrics and will not be discussed here.


Total THC and Total CBD were impacted by cultivar, sampling period, and location ( P < 0.05). Cannabinoid data is presented in terms of averages across all locations at each time point. THC and CBD generally increased from week three to week five, with cultivars exhibiting varying optimal harvest intervals for both compliance (THC) and profit potential (CBD) between weeks 5 and 7. This suggests that growers will want to consider both CBD and THC production when making harvest decisions.


The reality is many CBD dominant hemp cultivars currently on the market will go “hot” (Total THC >0.3%) if not monitored appropriately during flowering. To illustrate, 11 (65%) of the cultivars in the check program exceeded the regulatory limit at some point during the flowering period. Even with increased caution from farmers 29% of the 2,000 samples submitted into the MHD were above 0.3% Total THC regulatory limit across the 2020-2022 growing seasons.


Growers are encouraged to test their crop frequently during later stages of flowering to maximize production of cannabinoids while maintaining compliance. This data would suggest that the optimal sampling date for many cultivars will likely be 5 to 7 weeks (35 to 49 days) after flowering initiation to remain compliant. Data from the 2021 and 2022 growing seasons has been utilized to develop estimated compliant harvest schedules based on 95% confidence intervals.


CBD:THC is impacted by cultivar, sampling period, environment, and cultivar by environment interactions ( P< 0.05). CBD:THC of many of the hemp cultivars were unaffected by sample timing, remaining consistent throughout flowering. Similarly, CBD:THC of many of the hemp cultivars was unaffected by grower location, remaining consistent across environments. This supports previous work by researchers from Cornell University showing that CBD:THC remains stable throughout flowering for uniform cultivars.


Results show that most CBD dominant cultivars exhibit a linear (or curvilinear) relationship between Total CBD (%) and Total THC (%). Given this relationship, Total CBD (%) infrequently exceeds ~8% without exceeding the regulatory threshold of 0.3% Total THC. Considering that CBD:THC is mostly stable across flowering periods and environments, cultivars with a stable CBD:THC (>25:1) throughout flowering will help to maximize profitability while maintaining compliance. It should be noted that some cultivars are more impacted by environment or genotype* environment interactions; as such, heterogeneity across and within cultivars can make agronomic performance and cannabinoid development less predictable and difficult to evaluate. Due to the non-uniformity of the flowering process, unstable/non-uniform cultivars could reach maturity at different points in the growing season, which could have adverse impacts on testing and harvesting strategies at the field level. For this reason, growers may want to consider uniformity of growth and development of plants within a cultivar when making selections to avoid issues in the field for compliance and harvest.


For CBG Dominant cultivars, THC and CBG increased over time, with cultivars exhibiting varying optimal harvest intervals for both compliance (THC) and profit potential (CBG). None of the three CBG dominant cultivars exceeded the THC threshold for compliant hemp by the week 7 sampling period. CBG dominant cultivars may provide an alternative cropping option for those looking to reduce risk of noncompliance compared to production of CBD dominant cultivars


Growers will want to consider the following factors when making variety selections in their region:  Seed Quality (Germination, Uniformity, etc.),  Maturity Group (Photoperiod), Agronomic Performance (Yield and Quality), and Cannabinoid Development (Compliance Potential)


Growers will want to consider the hardiness zone and maturity group, as well as their potential interactions, when making variety selections. For example, growers in northern latitudes may want to plant earlier maturing cultivars to maximize the shorter growing season compared to their southern counterparts. In a similar fashion, growers may wish to grow cultivars of varying maturity groups to diversify and stagger field operations. Importantly, cultivars with a history of compliance may not be suited to a region while some cultivars with a history of high performance may not be reliably compliant. To better understand cultivar agronomic performance in a similar region, growers are encouraged to access local university cultivar trials for the most accurate regional information. Similarly, growers are encouraged to access the Midwestern Hemp Database and Cultivar Check Program Reports for the best information available regarding compliance potential of evaluated cultivars.

Participation Summary
286 Farmers participating in research

Educational & Outreach Activities

250 Consultations
4 Curricula, factsheets or educational tools
2 On-farm demonstrations
2 Published press articles, newsletters
22 Webinars / talks / presentations
6 Workshop field days

Participation Summary:

1,540 Farmers participated
4 Ag professionals participated
Education/outreach description:

Select outputs (journal articles,  research reports, and presentations) have been created annually. Research reports for this project are shared via grower-cooperator networks and posted to university webpages. 

During the winter/spring educational season, results of the Cultivar Check Program and Midwestern Hemp Database are shared at various conferences, seminars, and workshops. 

Growers met biweekly during the growing season to perform continued education efforts and encourage discussion/program improvement. 

During the growing season, educational events/webinars were hosted regularly via partnering growers to update program participants and stakeholders on our research efforts. 

Consultations are provided regularly for growers looking to utilize data for this project on their operations. This includes making variety selections in addition to providing insight on sampling and harvest recommendations. 



Learning Outcomes

32 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

286 Farmers changed or adopted a practice
2 Grants received that built upon this project
3 New working collaborations
Project outcomes:

Participating researchers and farmers will learn/identify suitable hemp varieties and production strategies in the NCR

Participating researchers to learn/identify various laboratory analytical methods and interpretations across states in the NCR

Participating researchers to learn general principles of on-farm trials to incorporate into other aspects of their farm 

Industrial hemp producers and processors may use the database to influence decisions regarding hemp variety selection, production strategies, and harvest schedules 

Industrial hemp producers and processors to utilize information from laboratory proficiency programs to inform decision-making regarding laboratory selection and interpretations of laboratory analysis. 

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.