Promoting crop diversification and soil health for cut flower production

Progress report for OW19-346

Project Type: Professional + Producer
Funds awarded in 2019: $49,999.00
Projected End Date: 08/31/2022
Grant Recipient: Utah State University
Region: Western
State: Utah
Principal Investigator:
Dr. Melanie Stock
Utah State University
Dr. Brent Black
Utah State University
Dr. Daniel Drost
Utah State University
Dr. Larry Rupp
Utah State University
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Project Information


Title: Promoting crop diversification and soil health for cut flower production

Summary: Growing cut flowers as a high-value crop has become popular across Utah in the last five years because of the crop’s unmatched profitability and small space requirements. Yet to date, minimal research and cultivation information exist for Utah, which has resulted in grower adoption of out-of-state materials that are not appropriate for Utah soils or climate conditions. Over-application of fertilizer and use of unsuitable soil amendments have introduced soil health, long-term productivity, and environmental sustainability risks. Therefore, the goal of this project is to answer the following research questions by testing a premium cut flower, Dahlia ‘Café au Lait’:

  1. What nitrogen rates are needed to maximize economic return on yields (stem length, bloom diameter, and total number of blooms per plant) without buildup of nutrients and salts that negatively affect soil heath, productivity, and environmental sustainability?
  2. What are current management practices and market prices being used by cut flower farmers in Utah?
  3. How do native soil conditions and climate impact nutrient management and subsequent yields?

This project will establish Dahlia trials at the Utah Agriculture Experimental Station – Greenville in North Logan, UT, to test and develop in-state nutrient management plans. Participatory research will also be conducted with growers to document present management practices, subsequent soil test results, yield, and profitability data on ranging soil types and climates in the state. Multiple Extension education outreach activities will be organized through conference presentations, field days, farm tours, and a grower association. Social media and digital resources will be developed to produce accessible in-state references on cultivation and soil health. Creating Utah-specific resources for cut flower cultivation that highlight soil health promotes innovative markets for growers by increasing resource use efficiency, yields, and environmental sustainability.

Project Objectives:
  1. Develop nutrient rate recommendations for Dahlia cultivation through research trials with five nitrogen rates and data that include soil test results (nitrogen, phosphorus, potassium, pH, and salinity) and yield (date of first harvestable bloom, stem length, bloom diameter, and total number of blooms per plant) over two growing seasons (2019 and 2020).
  2. Determine baseline production and profitability of Dahlia through a two-year on-farm study of soil test and yield data from six participatory farms (2019 and 2020). The growers span across a 200-mile transect in Utah that represents the diverse soil types and ranging climatic conditions, where the majority of the state’s population resides and manages land (the Wasatch Front).
  3. Raise soil health awareness through in-person outreach events (presentations and field days with needs assessments) and social media documentation of field work that includes live Q&A with the project director during 2019 and 2020.
  4. Produce clear, specific, and publicly available in-state recommendations for Dahlia cultivation to provide a reference for current and future growers, and responsible hobbyists. These Utah-specific grower guides (Fact sheets, bulletins, and video) will be available in 2021.

Please see the Gantt Chart (Figure-4-Timeline).

Objective 1 Timeline: Establish USU’s Dahlia ‘Café au Lait’ trials in May 2019 and complete first growing season in September 2019. Analyze first year data during Winter 2019-2020. Repeat trials during May – September 2020 and analyze two-year dataset to finalize recommendations during Winter 2020-2021.

Objective 2 Timeline: Establish Dahlia ‘Café au Lait’ trials on six participatory farms in May 2019 and complete first growing season in September 2019. Analyze management and soil test data during Winter 2019-2020 to provide one-on-one training in fertility management in Spring 2020. Complete the second field season during May – September 2020 and analyze the two-year dataset to refine recommendations during Winter 2020-2021.

Objective 3 Timeline: The Utah Urban and Small Farms Conference will take place each February (2019-2021). 2019 and 2020 Field Days will take place each May and Farm Tours will take place each August. During these outreach events, the Utah Cut Flower Growers Association will meet. Video will be recorded during field activities that fall within Objective 1 timeframes. FacebookLive will take place in 2020.

Objective 4 Timeline: Begin data analysis in 2019, finalize data analysis in 2020-2021, and disseminate guides by 2021.


Click linked name(s) to expand
  • Heather Barnes - Producer
  • Dr. Brent Black - Technical Advisor
  • Dr. Dan Drost - Technical Advisor
  • Heather Griffiths - Producer
  • Kyler and Brittany McPherson - Producer
  • Fawn Rueckert - Producer
  • Dr. Larry Rupp - Technical Advisor
  • Julie and Ryan Williams - Producer
  • Shelly Zollinger - Producer


Materials and methods:

Objective 1: Develop nutrient rate recommendations for Dahlia cultivation through research trials over two growing seasons.

Dahlia ‘Café au Lait’ will be established in May 2019 at the Utah State University Agriculture Experimental Station – Greenville (UAES) in North Logan, UT. Five nitrogen rates will be tested during 2019 and 2020 growing seasons: 0 (control), 56, 112, 168, and 224 kg Nitrogen ha-1. Each rate will be replicated three times with 15 plants per replicate. Soil will be sampled in each plot prior to planting (April) and again in the fall after frost-kill (September-October). Soil tests will include: pH, salinity, phosphorus, potassium, nitrogen analytes, and total carbon. Tissue samples will be collected to assess nitrogen uptake through dry matter and nitrogen analytes, similar to Ahmad et al. (2012). During the growing season, yield data (plant emergence, date of first cuttable stem, total number of stems per plant, bloom diameter, and plant height) will be collected. Soil tests, application rates, and yield will be analyzed to determine nutrient management recommendations for Utah soils. To account for environmental variability during each growing season, a weather station will capture atmospheric conditions and automated sensors will measure soil temperature and moisture of the root zone. Tuberous roots of the Dahlia will be dug in the fall and stored until spring.

During winter 2019-2020, preliminary soil fertility recommendations will be developed from analysis of first-year data. After the completion of the second growing season, the two-year dataset will be analyzed to refine soil fertility recommendations for publication in winter 2020-2021. Melanie Stock will oversee the field trials and data analysis. Dan Drost, Brent Black, and Larry Rupp will consult as needed on field plot establishment and fertilizer response.

Objective 2: Determine baseline production and profitability of Dahlia through a two-year on-farm study with six participatory growers.

Each producer will receive 10 Dahlia ‘Café au Lait’ to grow on their farms (Figure-1-Location-Map). To minimize untargeted variables, the following directions will be given: Dahlia roots must be spaced two feet apart and receive at least six hours of sun (USDA, 1977). Utah State University (USU) will soil and tissue sample, as in UAES trials. During 2019, growers will cultivate Dahlia according to their standard practices. Yield (plant emergence, date of first cuttable flower, stem length, bloom diameter, and total number of stems per plant) and management activities (fertilizer application, tillage, staking, pruning, etc) will be recorded on data sheets (Figure-2-Record-Sheet-for-Growers). Prior to planting for 2020, USU will train growers to interpret their soil test results, explain yield differences compared to UAES trials and other growers, and provide nutrient management plans for 2020. Growers will follow USU guidelines and record the same data as in 2019.

Soil type, nutrient status, climate, and yield will be analyzed for Dahlia across the six farms to evaluate and refine UAES fertilizer rates in 2020. Melanie Stock will oversee the on-farm research and data analysis.

Objective 3: Raise soil health awareness through in-person outreach events and social media.

Project data will be incorporated into organized outreach events. One session for cut flower production at the Utah Urban and Small Farms Conference, one USU-hosted field day, and one grower-hosted farm tour will be organized by Melanie Stock each year. She and her graduate student will present on the research data generated by this SARE project. Melanie Stock will also establish the Utah Cut Flower Growers Association to facilitate regular meetings, networking, and communication. Dan Drost, Brent Black, and Larry Rupp will present on relevant topics to the farmers (high tunnel production, irrigation, shading, and greenhouse management) at the conferences and field days. Needs assessments will be conducted after each presentation (Figure-3-Needs-Assessment).

Video will be recorded of project implementation, data collection, and general field activities. Seasonal shorts will be posted on Facebook and then developed into a full-length FacebookLive presentation that will also be stored on the Production Horticulture Website as a digital resource ( Data on Facebook view numbers, view time, likes, and comments will be recorded, as well as the number of views and downloads from the Production Horticulture website. Melanie Stock will oversee online media activities.

Objective 4: Produce Utah-specific grower guides that are available by 2021.

One Fact Sheet will detail Dahlia cultivation for Utah, explaining soil health and nutrient recommendations with step-by-step calculations for sustainable fertilizer application and have corresponding video footage. The Extension Bulletins will cover 1) the nitrogen rate study and 2) grower trials and perceptions. Melanie Stock will oversee these publications and Dan Drost, Brent Black, and Larry Rupp will serve as coauthors.

Participation Summary
6 Farmers participating in research

Educational & Outreach Activities

40 Consultations
1 Curricula, factsheets or educational tools
2 Online trainings
2 Published press articles, newsletters
2 Webinars / talks / presentations
1 Workshop field days
26 Other educational activities: Other activity refers to our social media outreach - we had 11 posts in 2019 and 15 posts in 2020 that discussed planting, harvest timing, virus incidence/identification/testing, and common regional pest control, and storage for sales.

Participation Summary:

35 Farmers
60 Ag professionals participated
Education/outreach description:
  • Consultations: conducted two to four times for each farm in the study, as well as two additional flower farms (8 priority farms in Utah). The first consultation was on 5/24/19, during which dahlia production strategies and soil fertility/sampling were discussed with SARE farm participants (6 farms). The second consultation was on 9/6/19 with seven farms due to a viral outbreak that occurred at the USU research farm. Dr. Stock began a new partnership with USU Plant Pathologist, Dr. Claudia Nischwitz; together they traveled to flower farms to consult on pest and viral disease presence, survey farms, and collect plant tissue for lab testing. A follow-up consultation occurred electronically on 10/13/19 with the farms to update them on lab results and best management practices, as the viral outbreak was found across the state. A final consultation in 2019, was on 11/1 with the six farms in the study. Retrieving tubers, soil testing, and pests and disease were discussed. The following year, due to COVID-19, communication was not possible to do in person. Therefore, email, postal, phone, and Zoom correspondence methods were used. The study continued in 2020. Because travel was restricted, we sent plant material, data sheets and postage for sending in soil samples to each farm, coordinating efforts over email. We did this with each from in May 2020 and October 2020. During the growing season, we also provided direct consultation to growers in and outside of the study to troubleshoot production issues. 
  • Online training: two videos were produced regarding basic soil nutrient management and health. The first video was a step-by-step tutorial for collecting appropriate soil samples in a microfarm or garden bed. The second online training is a guide for interpreting soil test results from the lab - what the results mean and how to follow recommendations. The videos were promoted and shared to Instagram and Facebook (IGtv and FBwatch. The videos have been viewed 1,331 times and 1,659 times, respectively, in 2019. At the USU Urban and Small Farms Conference in 2021, one of the on-farm participants presented on cut flowers marketing and sales, directly including 'Cafe au lait' dahlias as one of the most profitable and sure sales for growers. In 2021, a presentation on soil health was given based on sustainable nutrient management at the Utah Urban and Small Farms Conference. 
  • Published press articles, newsletters: In 2019, Dr. Stock co-established and became a board member of the Utah Cut Flower Farm Association with top growers in Utah (website: The Association now has over 50 members at 9 months old. As part of the Association’s quarterly newsletter, Dr. Stock authored one newsletter article in August 2019 to provide an overview of USU cut flower research to growers, and a second in October 2019 to detail dahlia management and lessons learned from the 2019 USU trials.
  • Webinars/talks/presentations: We produced one presentation on dahlia production at the 2020 Utah Urban and Small Farms Conference (04 Mar. 2020). There were approximately 60 attendees. Evaluations of the presentation are sill being processed. We plan to present additional data at the 2022 conference.
  • Workshop/field days: We hosted a high tunnel workshop on general horticulture production practices that was followed by a hands-on farm tour on May 22, 2019. There were 60 attendees from Utah and Idaho. At this event, Dr. Stock gave two workshop presentations (one on soil management in horticulture systems and one on general cut flower production practices) and a farm tour of the cut flower trials, including the dahlia study. Dr. Drost and Black (co-PIs) discussed other production factors, such as temperature management, farm site selection, and other horticultural crops.
  • Other Educational activities: A survey at the 2019 Utah Urban & Small Farms Conference indicated 58% of cut flower growers preferred Instagram to any other social media platform (Facebook was second-most popular at 33%). In response to this demand, we created the @usu_smallfarms account on Instagram and Facebook (with primary focus on Instagram). This account has been popular in connecting with growers and successful in sharing real-time information, as well as engaging educational content. We developed and shared 11 posts regarding the SARE dahlia study. These posts ranged from soil nutrient management, to harvest practices, to pest and disease identification and management as outbreaks occurred, and tuber storage. Social media content related to dahlia production from this grant averaged a 21% engagement rate among followers (>6% is considered high). As of April 2021, the account has over 2,000 followers that include state, regional, and national cut flower growers.

Learning Outcomes

50 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key changes:
  • Soil nutrient management in Utah - the importance of soil testing to understand existing nutrient levels, particularly phosphorus, potassium, and soil salinity levels before applying fertilizer.

  • Soil nutrient management in Utah - understanding fertilizers and soil amendment guaranteed analyses, and selecting sources that are low in phosphorus and potassium when soil tests indicate high levels.

  • Soil nutrient management in Utah - compost production and use with saline soils, excessive phosphorus and potassium soil test levels.

  • Soil Health - tillage ("to till or not to till")

  • Pest and disease management - identifying problems, subscribing to USU IPM updates, and control methods.

Project Outcomes

10 Farmers changed or adopted a practice
10 Farmers intend/plan to change their practice(s)
2 Grants received that built upon this project
5 New working collaborations
Project outcomes:

This project is improving production efficiency, soil health, and economical sustainability. The goal of this study is to develop soil nutrient recommendations for dahlia and provide growers with a firsthand experience regarding sustainable nutrient management: the importance of soil testing and only adding nutrients indicated by the test, as opposed to relying on intuition and adding balanced amendments and fertilizers that often lead to excessively high soil nutrient levels (Phosphorus and Potassium) and salinity. This project also develops optimum nitrogen rates to increase flower yield. We are accomplishing these objectives through our research farm and on-farm trials.

At the onset of the project in 2019, all on-farm participants had high to excessively high soil test phosphorus and potassium because of unbalanced nutrient management plans. However, by 2020, 5 of 6 farms have reduced their phosphorus levels and 3/6 have reduced their potassium by changing soil fertility practices. Because the levels were so much higher than optimal, it will still take several years of continuing these practices to bring levels into the optimal range.

In addition to this, the study exposed a devastating disease issue for Utah dahlias. This created a new collaboration with USU Plant Pathologist, Dr. Claudia Nischwitz, who has now changed her program emphasis to understand cut flower diseases, particularly those of dahlia. Through work and funding with Dr. Nischwitz, we conducted a state survey of dahlia diseases and determined dahlias at every surveyed farm had at least one viral disease, and up to three. These viruses exhibit a range of symptoms: from visually asymptomatic foliage to severe stunting and discoloration. Despite this range of symptoms, virus infection leads to reduced yields, which can be difficult to quantify when all farm dahlia stock are infected (i.e. there is no virus-free "control" for comparison, thus all dahlia can be perceived as a premium high-value, but less productive cut flower). Utah State University can now offer testing to growers and other dahlia enthusiasts. Drs. Nischwitz and Stock have written four grants to supplement SARE funding and other operating funds, two of which were funded. As a result, we are also developing tools to identify virus presence, expanding soil testing (some viruses are affected by soil nutrient levels and ratios), and increasing consultations and social media presence to address the challenges of growing dahlias. The PI was also able to work with industry to find plant stock produced from clean laboratory practices that ensures virus-free dahlias for the field season in 2021.  

The incidence of virus, in addition to variability in the environment, testing nitrogen management has been a challenge. Therefore, we extended the study to include a greenhouse trial of nitrogen rates on a similar cultivar - it is popular for sales, yet has more resistance to disease, allowing us to have additional data for testing fertilizer application rates. This trial began in Nov 2020 and is ongoing. 

Lastly, Western SARE's support has led to a greater understanding of the dahlia wholesale market, particularly florist preferences, which will improve sales for farms. Large, out-of-state private farms have standardized an 18-inch stem and clean bloom as a marketable Dahlia 'Cafe au Lait'. However, as part of this study, we are working with a farm co-op that sells to florists and reports pricing and preferences. We have found marketable 'Cafe au Lait' stems only need to be 6-inches long, which will result in significantly more blooms being classified as marketable, as opposed to culls. 

Nutrient and disease management, as well as the floral market, are critical needs that we are addressing in Utah. Support from Western SARE has revealed the urgency and has also helped facilitate communication between researchers and farmers, and farmer-to-farmer. The first year of this study provided exploratory data with great breadth, the second year of this study established the widespread issue of dahlia disease, but also improved soil nutrient management. 2021 will be the final year of the study (per a no cost extension) and will be a year of optimizing findings, as farmers and researchers now have more background in soil fertility management, greater awareness of dahlia disease prevalence, and floral market preferences. We have also sourced certified disease-free stock that was lab-cultured to bolster nutrient management results. This third year of data will improve the robustness of the field data, as well as allow us to complete a greenhouse study of nitrogen application rates. From this, we expect to see changes in production methods – from more selectivity in purchasing dahlia stock, to fertilizer decision-making in the field and greenhouse systems, to sales.

Success stories:

At the onset of the project in 2019, all on-farm participants had high to excessively high soil test phosphorus (P) because of unbalanced nutrient management plans, particularly excessive use of compost and complete fertilizers. However, by 2020, 5 of 6 farms have reduced their soil test Pby changing soil fertility practices. In 2019, the average soil test P was 115 ppm (values 21-30 are considered optimal for Olsen soil tests; values above 60 are considered "very high") and by fall 2020, the average soil test P was 85 ppm due to reducing to eliminating phosphorus application. Because the levels were so much higher than optimal, it will still take several years of continuing these practices to bring levels into the optimal range. However, one uplifting success story from this has been that the farmers are sharing the changes they have made with other farmers. The cut flower farmers have a highly engaged Facebook group in which they ask one another questions. It is an amazing feeling to hear recommendations from the project shared by the farmers to one another - particularly the need to soil test to see what levels are and the need to be mindful about compost application. 

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.