Final report for FW23-429
Project Information
There is an increasing demand for locally grown, sustainable produce, including cut flowers. In Utah, like much of the West, water availability is a major concern for farmers and this will likely only continue. While the benefits of growing locally are substantial, water use for conventionally grown flowers is increasingly unsustainable.
Many vegetable growers (notably tomato, salad greens and hemp production) successfully grow high quality crops in controlled environments, but little research is available for floriculture.
We looked at the feasibility of growing high-value crops, such as dahlias, hydroponically indoors to mitigate both the high water usage and pest and environmental pressures of field grown crops. Research species included five common floriculture crops chosen for their profitability and species diversity: dahlias, snapdragons, cosmos, scented sweet peas and lisianthus. We tested the best methods for each crop grown, and compared water usage directly in conjunction with a field crop of the same variety. We measured water usage, supplemental fertilization and amendment needs as well as the quality of the flowers with this research, focusing on stem number and length per plant, bloom size, and overall quality.
Our goal with this research aimed to produce a product of similar or higher quality to field production, with significantly less water and land resources. We intend to share our methods and results with other growers to create a standard growing practice in places with low water availability, few land options, or challenging seasonal conditions for growing conventionally.
By studying the feasibility of growing floriculture crops hydroponically, we tested methods that reduced water input while maintaining a marketable, local cut flower crop held to the same standards as conventionally grown cut flowers. Using this information we shared what we learned with other flower farmers the amount of water saved, hydroponic crop quality, costs involved, and best growing methods for specific crops.
Research Seasons 2023 and 2025: largely the same, with initial fall data processing used to modify second season (if needed) and data processing in second year geared toward total research results. 2024 was omitted due to weather and growing inconsistencies that impaired quality data collection from the control group. Conclusion of second season and data processing has prompted initiation of education plan.
| Date | Activities | Team Members |
| March | Soil samples taken for baseline data; Seeds started in growth chamber; order supplies still needed for upcoming season; review season plan with TA; photo and documentation of process |
PI: Anna Zack, TA: Dr James Cohen (Jim Cohen), Benjamin (Ben) Zack Anna: Soil samples, seed starts, supplies |
| April | Soil amendment applied based off of soil test; fields tilled for planting; drip line laid and tested; seedlings transplanted to larger seedling trays; Hydroponic setups installed, pumps and reservoirs tested; photo and documentation of process |
Anna: transplants, field preparation. Documentation Ben: hydroponic installation and equipment testing. Documentation |
| May | Transplant seedlings in field and greenhouse when weather appropriate; mulch field rows; photo and documentation of process |
Anna: transplant seedlings. Documentation. Ben: Equipment running, routine and troubleshooting maintenance. Documentation |
| June | Monitor plant progress, record findings; harvest and grade as flowers bloom; photo and document process |
Anna: Plant care and harvest. Data collection and documentation. Ben: Equipment maintenance. |
| July | Monitor plant progress, record findings; harvest and grade as flowers bloom; photo and document process |
Anna: Plant care and harvest. Data collection and documentation. Ben: Equipment maintenance. |
| August | Monitor plant progress, record findings; harvest and grade as flowers bloom; photo and document process |
Anna: Plant care and harvest. Data collection and documentation. Ben: Equipment maintenance. |
| September | Monitor plant progress, record findings; harvest and grade as flowers bloom; photo and document process |
Anna: Plant care and harvest. Data collection and documentation. Ben: Equipment maintenance. |
| October | Conclude research for season as frost date arrives; prep field and greenhouse for winter dormancy; photo and document process |
Anna: Last harvest prior to frost date. Data collection and documentation. Pull drip lines, mulch and prepare farm for winter months. Ben: Remove plants from hydroponics, inspect and clean equipment, remove water and prepare for winter months. |
| November | Process all data collected for summer; season report created; plan and modify next season's research plan; order seeds and supplies for next growing season |
Anna: Data processing, report. Modify plan for next growing season if needed. Jim Cohen: Review data processing, review report |
Cooperators
- - Technical Advisor
- - Producer
Research
Our research plan compared field grown cut flower crops to hydroponically grown crops to compare water conservation and product quality between the two methods.
Project site: We conducted research on two growing sites for this project. The first site, our current farm field, where conventionally grown crops were planted in 4'x50' raised soil rows. The second site consisted of an enclosed greenhouse structure outfitted with a hydroponics setup. Both sites were located in Ogden, Utah. Both had the same species and number of plants per species, seeds started and grown at the same time and season, and were provided with the appropriate nutrient amendments, substrate, light, and water requirements for successful growth.
Research design: We designed our project using two commonly used commercial methods for growing hemp and vegetables hydroponically: the ebb and flow (or flood and drain system), and the nutrient film transfer system. There are a number of hydroponic methods in use, with ample research to demonstrate the best practices for growing specific food crops. We hypothesized that an ebb and flow model successfully used for hemp would correlate well with larger flowering plants such as a dahlias, that require large root space and plant support. For other crops, such as vines (e.g., tomatoes and cucumbers), we suspected that the nutrient film transfer method would have greater success, and implemented it for vining sweet peas. Additionally, smaller herbs and greens crops commonly grown in nutrient film transfer systems correlate well for smaller cut flowers such as snapdragons, cosmos and lisianthus. By testing different hydroponic systems, we aimed to find the greatest crop success for each species and identify specific needs for each crop.
We compared five common and valuable crop species: dahlias, snapdragons, cosmos, lisianthus, and sweet peas. These crops were chosen for three reasons: 1) their popularity among flower farmers, 2) marketable value and 3) diversity in growing condition requirements. All crops were grown from seed with the exception of dahlias, which were grown from cutting stock. Seeds and cuttings were started in the same growth media at the same time for both the hydroponic greenhouse and the field to reduce variability in the test and control. An equal number of seedlings will be allocated to each planting group (field control, ebb and flow, and nutrient film transfer). Only healthy looking and uniform seedlings were be transplanted.
The field control plot was soil tested and amended based on soil test results prior to planting. Drip irrigation was laid at 8" intervals along the 4'x50' raised beds, and then covered with chopped leaf mulch for weed suppression and water retention. Plants were transplanted on a timeline according to weather conditions and hardiness, and varied each season studied. Plants were watered according to weather conditions and soil moisture meter readings. Additional soil amendments were added as appropriate throughout the growing season.
The greenhouse had two hydroponic setups. The first was an ebb and flow table, where water and liquid nutrient filled a shallow table for 5-10 minutes then drained completely, repeating every 6-24 hours depending on plant size and water requirements. The plants were grown in water-permeable containers sized to their mature growth and filled with soilless coco coir substrate. The second hydroponic setup was a nutrient film transfer setup, where channels were pumped with a small, continuous supply of water and liquid nutrient that passively flowed through plant roots. The plants were grown in rock wool cubes placed directly in the channels, held in place with 1" square holes in the channel cover. Both systems were tested for water pH level, salinity and nutrient content, and were adjusted as needed.
Plants were evaluated from the time of transplanting into the field or greenhouse up until post-harvest storage. We used a visual qualitative grading scale to determine overall plant health weekly, observing growth, leaf size and color, disease symptom presence/absence, and insect or environmental damage if any. Once flowering, we added flower qualitative grading, recording flower size and color vibrancy, as well as any defects from disease or insect/environmental damage present. We also recorded quantitative values to measure number of stems, stem length at harvest, percentage of marketable blooms of total, and days to maturity. Once harvested, we stored a portion of the flowers in a floral holding solution in a cooler according to post-harvest best practices. We recorded longevity in cold storage to determine any differences in transport ability and vase life.
In addition to overall plant and flower quality, we monitored water and nutrient usage. In the field, drip lines were metered to calculate gallons used over the season. Typical water-conservation measures we take in our field were implemented, such as shade cloth and mulching. Amendments were recorded as they are used. Greenhouse water and nutrients were contained in a 200 gallon tank, with water levels measured at time of water testing to monitor water usage. Additional water added was metered to calculate gallons used over the season. Nutrient was supplemented as water testing indicated.
Our research was conducted over two growing seasons: 2023 and 2025, May through September for northern Utah. We originally planned on 2023 and 2024, but had both weather and equipment complications that reduced the amount of usable data. We chose a two-year study to account for normal variation in year-to-year growing conditions. Our data compared specifically the number of usable stems, overall bloom quality, and water usage between hydroponic and field grown. Additional information collected compared nutrient requirements, plant health, cost of production, and labor intensity needed to effectively grow the crop. For quantitative and qualitative traits, we used a Wilcoxon-Kruskal-Wallis test to examine statistically significant differences between treatment and control.
We found that hydroponics saved an overall average over two seasons of 73% less water than field production. Dahlias needed additional water both in the greenhouse and in the field, and we saw a 25% decrease in water usage for hydroponic ebb and flow table over field production. While we still saw a water use reduction, the ebb and flow table used had more evaporation in the greenhouse than the nutrient transfer channels, and was not as water efficient. Early season sweet peas needed very little water in the field, and actually needed more water in the greenhouse in the nutrient transfer system where spring soil moisture was not available. For sweet peas in a wetter 2023 they used 400% more water in the greenhouse. 2025 was a much drier spring, and they used 150% more water in the greenhouse. Snapdragons and cosmos were both long season producers, so while the initial early season water use in the greenhouse was higher, June through August balanced it back out and we saw a 90% reduction of water usage using nutrient film transfer channels. Lisianthus are a relatively xeric crop, so less watering was necessary in the field, while the same nutrient film and ebb and flow methods using the same amount of water as for the other species in the system. Lisianthus used about 55% less water using hydroponics than with field production.
Nutrient amendments were added for field production in the form of composted horse and goat manure at the start of each season to add nitrogen and organic matter. Based off of soil testing, no amendment for phosphorus or potassium was indicated. Bare soil was mulched with chopped leaves to reduce nutrient leaching and retain moisture. Fish emulsion fertilizer was used in all seedling production for both hydroponic seedlings and field-planted seedlings. Hydroponic water was tested and amended with a commercial hydroponic nutrient as needed, dosed for vegetable production. Because these amendments were dramatically different in nutrient need and dosing, and is incredibly specific to soil type, we did not feel that it was reasonable to compare consumption of one method over the other.
We found significant qualitative differences in crops. Greenhouse crops grown had little to no insect damage compared to field grown, which had significant late season grasshopper damage. Greenhouse crops grown hydroponically grew more quickly and bloomed more quickly for dahlias, snapdragons and cosmos (on average 1-2 weeks sooner). Blooms were largely of comparable vibrancy and size across species. Stems of dahlias and cosmos were comparable, but much thinner and easily snapped for snapdragons. Lisianthus grew quickly in the greenhouse but then stalled, and very few flowered in either season compared to the field production. We suspect that conditions were too wet in the hydroponic system. Sweet peas also did poorly in the greenhouse, which as cool season legumes could have been temperature-related or the absence of symbiotic bacteria in the nutrient film transfer channels that were present in the field soil.
Flowers held in storage and measured for vase life were indistinguishable between test groups for all species. While not an indicator of storage time or vase life, it was noted that weak stems for snapdragons tended to break in arrangements more often than field grown stems.
Research outcomes
In our first season we focused on the possibility and practicality of growing cut flowers hydroponically. We used NFT channels to grow cosmos, sweet peas, snapdragons and lisianthus flower species and used an ebb and flow table to grow much larger dahlias. Setup of the equipment proved challenging due to significant shipping delays, and once we had all of our materials we spent much of the spring season fine tuning pumps and sensors, finding the appropriate flow rate for our setup and each flower variety and the correct dose of liquid nutrient. We grew one single succession of all plants species simultaneously, starting in early June to harvest stage and mirrored the same species in the field plot. We found that cosmos grew exceptionally well in NFT channels and stem length and sturdiness were very similar to field grown. Snapdragons did similarly well, however the stems were thin. We will trial them again this growing season in spring and fall in addition to summer to see if greenhouse temperature was a factor, and will also grow them in soilless substrate in the ebb and flow table to compare. Sweet peas initially grew well but very few blooms of quality were recorded. This is very likely due to the temperature of the greenhouse as these are cool weather species.
2024 started off well, with seedlings establishing in both hydroponic and field production on track. Significant weather events in April and May delayed field production and a record heat in July and August hit crops especially hard. We had more protection from spring ice and summer drought in the greenhouse, however plants did poorly even in the face of fans and shade cloth as temperature reduction measures when outside temperatures exceeded 100 for multiple weeks. Due to the inconsistency between growing treatments we were able to collect very little data and made the decision to continue int0 2025 for our second growing season.
In 2025 we started our cool season crops earlier, and sweet peas grew more successfully in the greenhouse than in 2023, however still not as robustly as the field grown crop. We added a fall planting and saw poor production in the greenhouse, likely due to late summer heat when seedlings, and a moderate fall harvest in the field. Lisianthus grew initially very well in the greenhouse with very strong looking plants but did not produce many stems or flowers of a reasonable quality. We had great success growing dahlias with the ebb and flow table. The plants were healthy and large, with attractive blooms on long stems. They produced less blooms compared to the field, however there was no insect damage recorded in the greenhouse. With the exception of the occasional grasshopper caught in the greenhouse there was zero insect pressure and no plant or bloom damage from insects in the hydroponics greenhouse. We saw significant losses to grasshoppers in the field plots late in the summer, even when using protective bags over blooms. Our comparison field plot grew typically of a mid-season in Utah, needing daily watering but with good production. We had shorter than typical lisianthus stems but had good bloom quality, and uniform snapdragons and cosmos. Sweet peas in the trial plot also did poorly in the heat, although outperformed the greenhouse by more than double.
Given the information we collected, we would not recommend growing sweet peas or lisianthus in hydroponic systems. Further research into reasons they performed poorly would be helpful. We suspect a more precise nutrient ratio for the specific species could be effective, or reserch into a bacterial or fungal symbiont that could be utilized in a hydroponic system could both be advantageous in future research.
Snapdragons and cosmos performed very well in hydroponic systems, and the water savings were the most dramatic for these species. Insect damage was reduced as well for both species, particularly cosmos. Weaker stems were noted in snapdragons, so identifying varieties with stronger stems, or research using fans to simulate wind might improve the quality of the stems.
Dahlias also performed well in hydroponic ebb and flow tables. They used less water than field production, though by a smaller margin than other species, and had about 20% fewer blooms. Dahlia blooms experienced tremendous insect pressure in the field plot, which saw more than 30% loss in both seasons, which negates the reduced blooms in the greenhouse. Additionally, measures to reduce insect pressure were more labor intensive and not entirely effective in the field. Due to these factors, we would recommend hydroponic systems for dahlias despite the reduced blooms. Research into breeds with high production might help increase stem counts. Using drip lines over soilless media might reduce water evaporation in the greenhouse, and research on other hydroponic methods to compare to ebb and flow tables would be recommended.
Education and Outreach
Participation summary:
Our education and outreach objectives were to disseminate our findings through local floriculture networks, and create plain english and bilingual fact sheets to be distributed more widely. We intentionally waited until we had complete information, but with the conclusion of our second research season this fall have been able to process and start to to share our findings.
Since concluding the study and with a better picture of the data, we have been able to have multiple in-person discussions this past fall with local growers interested in hydroponic floriculture. We will use this information to create a bilingual fact sheet to share our findings with larger audiences within the Utah flower community. We were a featured speaker in a program through the Ogden Nature Center for water conservation, and are partnering to implement a hydroponic program with their education department.
Education and Outreach Outcomes
We have shared our final results at the conclusion of our 2 year study through partner conversations and talks with producers. We are creating a fact sheet of our findings and recommendations, which will be available in both spanish and english. We also have plans to offer our results to both the Utah Cut Flower Farmers Association as well as to the Association of Specialty Cut Flower Growers with the completion of the fact sheet in March.