Greenhouse research shifting focus to food crops

To meet the interest and needs of students and a changing greenhouse industry, the horticulture department at the University of Arkansas is shifting its focus to the controlled environment production of new and underused food crops.

By David Kuack

An increasing number of students majoring in horticulture at the University of Arkansas are focused on food crop production. Horticulture professor Mike Evans said there has been a shift in interest by the students from greenhouse-grown floriculture crops to greenhouse-grown food crops. Evans said that except for turf management, students interested in food crop production make up the majority of students majoring in horticulture at the university.

“More and more students who are interested in greenhouse production want to learn about growing food crops. To accommodate this interest, we are starting a new class in which we are teaching about the production of tomatoes, cucumbers, greens and other food crops. We are putting in different kinds of production systems including hydroponics. The students will have a really well outfitted lab where they can go in and they will be raising various food crops with different systems. It will be hands-on.”

Evans said the growing interest in greenhouse food crops has rejuvenated him and his program.

University of Arkansas horticulture professor
Mike Evans (right) is working with other professors
to develop a program on greenhouse food production
for both students and commercial growers. 

“As the ornamental side of the greenhouse industry has been undergoing consolidation with fewer but larger operations, we have seen an increased interest from the industry in growing greenhouse food crops,” he said. “The number of emails and phone calls related to greenhouse food crops have greatly increased.

“There are a lot of people growing tomatoes, peppers and cucumbers in greenhouses. So I started looking at greenhouse food production and found the area of herbs and greens in many respects has been neglected. There are people out there doing these crops, but if you look for referenced research or talk to people, there is a lot less solid research on greens and herbs.”

Evans has started working with fellow university horticulture assistant professor and breeder Ainong Shi.

“We are interested in looking at new species of fresh greens and the breeding of greens,” Evans said. “We are particularly interested in developing crops that can take Southern hot climates. By converting our facilities to focus on greenhouse food crops we are looking to become a central institution to study new species of greens, developing new crops, breeding new cultivars, and developing production protocols for these crops.”

Developing greenhouse food crops

Evans said the agriculture industry in the United States has been largely field-based, but there are signs that changes are occurring when it comes to controlled environment food production.

“Much of Europe and many parts of Canada and Japan are significantly ahead of the U.S. when it comes to the development of controlled environment food production systems,” he said. “We are very much in a catch-up mode.”

One of the crops that Evans will be looking at regarding new species is fresh greens.

“Most of the greens research, including breeding, being done in this country, by-and-large, is for field production,” he said. “Those same varieties that were originally evaluated in the field are then taken and grown in the greenhouse. We typically have not bred varieties for greenhouse production.

“We want to find greens that have lower inputs, that don’t need much water or fertilizer. They also shouldn’t have many pest problems, have a rapid production cycle and can especially take heat.”

Evans said the issue with heat is a major obstacle for greens grown in the southern United States.

“The problem that growers in the southern half of the U.S. run into during the summer is what kind of greens can they produce? Greens in the South are more of an early spring and late fall crop. The question is can we develop greens that can be grown in the heat of summer?”

Mike Evans said he is looking for fresh greens that have lower
inputs, including water and fertilizer, few pest problems, a rapid
production cycle and can do well in hot temperatures.



One of the crops that University of Arkansas researchers are working on is to develop a heat-resistant spinach.

“We had a breeder here, Teddy Morelock, who did a lot of spinach breeding,” Evans said. “He passed away, but left us with hundreds of spinach lines. We’re trying to figure out what we’ve got. Teddy never conducted greenhouse trials or evaluated the germplasm for production in greenhouses. All of his evaluations were done in the field. We might be sitting on the best spinach variety to grow in a greenhouse.”

Another crop that Evans is excited about studying is dandelion (Taraxacum officinale).

“Dandelion has a higher nutritional value than spinach,” he said. “It is loaded with iron, vitamins A and C and beta-carotene. It was considered a medicinal plant. The early immigrants to America brought dandelions with them for food. A lot of people suffered vitamin deficiencies and developed scurvy. So they brought the dandelions with them.”

Evans said dandelions can be grown quickly, don’t need a lot of inputs and are very heat tolerant.

“They are short day plants so they might need some night interruption lighting,” he said. “That’s not real a concern because the plants would probably be harvested before they flower.

“There is a great deal of genetic diversity in dandelions because they are spread worldwide and are segregated. There are a lot of flavors and traits. We are going to be collecting germplasm from all over the world. We are going to be breeding dandelions so that they develop into what we want them to be.”

Setting up a strawberry cam

As part of the National Strawberry Sustainability Initiative, Evans will be working with professor Elena Garcia, who is the university’s fruit specialist. The research they will be doing is part of a program funded by the Walmart Foundation, which is being administered by the university’s Center for Agricultural and Rural Sustainability.

“We want to demonstrate and teach growers about various types of hydroponic systems for strawberry production,” Evans said. “Those systems might include NFT troughs, gutters, Dutch buckets, etc. There are various types of hydroponic systems that we feel bring some significant advantages to the production of strawberries and help to promote a number of sustainability goals in the program’s guidelines.”

Evans said the type of structures used to grow the strawberries will also be discussed.

“If a grower considers using high tunnels, he can extend the season,” Evans said. “Or a grower might consider using drop wall greenhouses. There is the possibility of providing heat, which could result in year-round production. There are a lot of possible benefits for our growers.”

Evans and Garcia have been traveling around the state and meeting with growers talking to them about the different production systems and explaining how they can be used for strawberry production. Evans said many of the growers that he and Garcia have met with didn’t know about the differences in the production systems and didn’t understand the differences.

University of Arkansas professors Mike Evans and Elena Garcia
will be teaching growers in their state about various types
of hydroponic systems for strawberry production.

Evans has renovated two of the university greenhouses in which various strawberry production systems will be installed and used to produce crops. About 4,000 square feet has been converted to hydroponic food production with about 1,600 square feet devoted to strawberries and the remaining used for greens.

“Our goal is to put in several different systems and to shoot video of what we are doing from the beginning to end,” he said. “We will shoot video of the assembly of the different systems as well as the production of the strawberries in each system. We will film and document in detail everything we do. The videos will walk the growers through all aspects of design, build, manage, maintain and grow the strawberries using a specific system.”

Evans said the videos will be used as an educational tool allowing growers to look at the different production systems and to see the advantages and disadvantages of each system. Evans has also been working with University of Arizona horticulture professor Chieri Kubota and research specialist Mark Kroggel to prepare videos on the strawberry production research they have been conducting at the university’s Controlled Environment Agriculture Center.


“Not every system is perfect for everyone,” Evans said. “Everyone has to look at what they are growing or planning to grow and what is their market. We want to use the videos as a way to demonstrate these systems to teach growers how to effectively select one and how to effectively use it.”

For more: Mike Evans, University of Arkansas, Department of Horticulture; (479) 575-3179; mrevans@uark.edu.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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