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
Host Institution Award ID: G223-19-W7502
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/collapse or show everyone's info
  • 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. Note: Because of strong, and unexpected virus pressure with dahlia, the timeline was modified. In the first year, we purchased cuttings from a small farm. Unbeknownst to us, they were infected with several viruses that changed plant behavior and resulted in high mortality rates. In the second year, we sourced industry-standard tubers. According to large-scale companies for ornamental stock, fields are scouted and those with virus symptoms are culled, but no virus testing is conducted. We discovered significant virus incidence in this stock as well. Therefore, in our third year (as a result of the no-cost extension and a new industry connection), we were able to source virus-free stock. The third year of data is the basis for our recommendations because of strong plant production and lack of confounding behavior.

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. Note: We extended the study into 2021. Growers received consultation in 2020 and 2021. 

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. 

Notes: we wrote a fact sheet that was peer-reviewed on sustainable compost and manure application for small farms in 2019: This PDF was downloaded 1,846 times since October 2019 and the HTML version can be found here: We also wrote a fact sheet on how to soil sample, select tests, interpret nutrient recommendations, and calculate rates that was peer viewed and published in 2020: This was downloaded 588 times since July 2020. We anticipate publishing a dahlia production fact sheet in 2022 (a delay because of the additional year needed for data collection). 

Research results and discussion:

On-farm trial

The original objective of this study was to work directly with growers to assess productivity and profitability of dahlia, as well as to raise soil health awareness. The results of this study critically highlight the importance of sustainable soil management outreach for small farms. In tracking key soil indications for management, all farms had high to excessively high soil test phosphorus (P) (Figure 1). On average, soil test P was three to four times greater than the maximum optimal rate for general crop production. Soil test potassium (K) followed a similar trend (Figure 1), with average soil test K two times greater than the maximum optimal rate for general crop production. While soil test nitrogen (N) is not routinely tested to base nutrient application rates (i.e. management programs typically recommend blanket N application rates based on crop demand assumptions, not testing), results from this trial suggest intermittent nitrogen testing may be important for small farm systems to “check in” that soil test values are not becoming excessive (Figure 1). Moreover, regional recommendations for soil-based nitrogen lack specificity, as the general recommendation only describes maintaining 25 ppm or more when the nitrate-N soil test is conducted (Cardon et al., 2008). Therefore, no upper limit has been established. In the on-farm trial, soil nitrate-N levels were up to four times greater than this recommendation (Figure 1). Together, these results indicate small farms overapply nutrients, soil fertility management training that is specific to small farms is needed, there is value in including soil nitrate-N testing, and determining upper thresholds of soil test N is needed for additional management guidance.

The soil test results for macronutrients did not significantly decrease over the course of the study, which provides insight into strongly held values by cut flower farmers that will be important to incorporate into future Cooperative Extension programming, as well as the challenge of reducing levels once they become excessive. The use of compost and “natural” products were emphasized by most growers and incorporated every year. Though compost adds organic matter that is needed in Utah soils, compost also supplies high amounts of P and K, which can lead to excessive nutrient levels in soil, as well as salinity challenges. We are retesting some soil samples to ensure results. Soil salinity averaged around 2 dS m-1 for growers in this study (Figure 1), which is the threshold for soil test laboratories to flag soil as “high” for most horticultural crops. Though research is needed to establish incremental yield decline by soil salinity level with dahlia, 1.1 dS m-1 is considered to be the threshold for irrigation water for dahlia, highlighting the intolerance of dahlia to elevated salinity (Australian Water Quality Center, 2022). Nutrient loading and subsequently elevated soil salinity may help explain the low yields reported by growers, who averaged 1.5 marketable stems per plant in 2019 (±0.7), 1.5 marketable stems per plant in 2020 (±0.90), and 0.4 marketable stems in 2021 (±0.2). 

For consultations and outreach, growers were asked to document management. In 2019, only documentation was requested. In 2020, amidst the pandemic, email and phone conversations were conducted to recommend soil management approaches based on test results. In 2021, soil test reports were aggregated with recommendations. Creating visually appealing data tables and typing out recommendations as a one- to two-page handout that was delivered to each farm, appeared to be most successful in helping to convey needed management changes for dahlia. Having paper copies of yearly soil test results together on one page, with a simple, yet farm-specific and detailed, interpretation resonated with growers and will be incorporated into future outreach.

Research farm trial

In establishing nutrient recommendations for dahlia through a variable N-rate trial at the Utah Agricultural Experiment Station – Greenville Research Farm, data in 2021 were most promising. Strong virus incidence depressed results in 2019 and confounded the data in 2020 (Figure 2), as explained in previous reports. In 2021, virus-free stock were sourced through a new industry collaboration. As a result, total yield was greatest in 2021 and response to N application rates was more clear (Figure 2). Both 168 and 224 kg N per ha resulted in the greatest total yield of 12 stems per plant and marketable yield of seven stems per plant (Figure 3). With these yields, soil test values remained low (Figure 4). Application of P and K were determined based on spring soil test levels and USU Extension-based recommendations (Cardon et al., 2008), which resulted in a gradual increase in soil test P and K (Figure 4). While pH was similar to soils on growers’ farms, salinity at the research farm was notably lower, at less than 0.5 dS m-1 across N-rate treatments, which may help explain the greater yield at the research farm and highlights the importance of following establish P and K recommendations.


Cardon, G.E., J. Kotuby-Amacher, P. Hole, and R. Koenig. 2008. Understanding Your Soil Test Report. All Current Publications. Paper 825. <>.

The Australian Water Quality Center. 2022. Groundwater Salinity. Groundwater Group Fact Sheet.  The Department of Water, Land, and Biodiversity Conservation. <>


SARE 2022 Report figures - this file includes figures cited in the report. 

Dahlia production fact sheet formatted in progress - this file is a DRAFT and the research trial section is especially not updated. However the fact sheet is attached to share the amount of information we are learning about state dahlia production, much because of support for this project. 

Participation Summary
6 Producers participating in research

Research Outcomes

4 Grants received that built upon this project
7 New working collaborations

Education and Outreach

60 Consultations
3 Curricula, factsheets or educational tools
2 On-farm demonstrations
3 Online trainings
3 Published press articles, newsletters
10 Tours
4 Webinars / talks / presentations
2 Workshop field days
30 Other educational activities: Other activity refers to our social media outreach - we had 11 posts in 2019, 15 posts in 2020, 15 posts in 2021, and 1 post in 2022 that discussed planting, harvest timing, virus incidence/identification/testing, and common regional pest control, stem storage for sales, use of plastic mulch and tunnels, and storage of tubers for winter survival.

Participation Summary:

200 Farmers participated
60 Ag professionals participated
Education and outreach methods and analyses:
  • 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, as well as in May and Oct of 2021. During the growing season, we also provided direct consultation to growers in and outside of the study to troubleshoot production issues. In Sept 2021, we also toured six additional farms for dahlia production challenges - soil, nutrient, and irrigation management, as well as disease. 
  • 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. In 2022, a presentation on dahlia production and trial findings was given at the Utah Urban and Small Farms Conference. This webinar was recorded and can be watched here:
  • 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 125 members, monthly zoom webinars, and quarterly gatherings (e.g. farm tours and events). 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. In Dec 2021, a mini-grants program was established with the UCFFA that I chair. The goal is for the Association to give back to members, encourage farmers to explore innovative ideas that improve regional production, learn to discriminate sources of background information, and build confidence to then apply for larger national grants. To date, this has inspired one farm to apply for a grant through the national Association of Specialty Cut Flower Growers (ASCFG) and be selected for funding - her research is on dahlia production and investigating deficit irrigation. In 2021, Dr. Stock co-authored an ASCFG article in the Cut Flower Quarterly (Fall Edition): "Tackling the three challenges of dahlia production: bloom timing, nutrient management, and disease." 2021-Fall-Stock-and-Nischwitz-Tackling-the-three-challenges-of-dahlia-production. In 2022, we expect to finalize a dahlia production fact sheet for USU Extension. A draft is included here: Dahlia production fact sheet formatted in progress.
  • 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. In 2022, we presented on dahlia production and trial findings at the Utah Urban and Small Farms Conference (2/23/22). There were 122 attendees. This webinar was recorded and can be watched here:
  • 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. On March 24, 2022, we hosted a farm tour for season extension techniques that highlighted fruits, vegetables, and cut flowers (Dr. Stock led the cut flower session). 52 growers attended. 
  • 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 (see @usu_small farms on IG for posts). 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 2022, the account has over 2,300 followers that include state, regional, and national cut flower growers.
45 Farmers intend/plan to change their practice(s)
20 Farmers changed or adopted a practice

Education and Outreach Outcomes

129 Producers reported gaining knowledge, attitude, skills and/or awareness as a result of the project
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.

Success Stories

    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. 

    A second success story is, during the course of this project, I met another dahlia farmer (outside of the nutrient management study). She has become increasingly involved with research and wanting to sustainably manage her soil and water. As we worked together, she wanted to write a proposal for a farmer grant through the Association of Specialty Cut Flower Growers (ASCFG), a national organization, but was intimidated. I presented to the Utah Cut Flower Farm Association (UCFFA) on how to write a proposal - how to research previous information, what goes in the Introduction, Objectives, Methods, Budget, etc. As a result, she wrote the proposal and was funded. The proposal aims to evaluate water use by dahlias in effort to reduce application volumes. The dahlia research that SARE initially funded has not only led to more grant funding for researchers, but also farmers.


    A third success story occurred in Winter 2021, when we collaborated with an applied economist with a specialty in marketing. Together with the UCFFA, we designed a survey for florists to provide feedback on the wholesale market for cut flowers - we wanted to gauge the size of the market and potential growth. The results of the survey were staggering - the growth in demand for local flowers far outpaces our local supply, despite Utah adding 20-30 new farms per year (as of Sep. 2021, there were 105 known cut flower farms). Moreover, dahlia was listed as the top crop that florists want to source locally. This highlights the importance of this Western SARE grant that first funded our dahlia research and is helping to increase yield per area, and the importance of focusing on nutrient management with dahlias as the first cut flower crop.

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.