Looking for additional controlled environment food crops?

Genhua Niu, professor of urban horticulture at Texas A&M AgriLife Research, is conducting greenhouse and vertical farm trials with Asian vegetables to determine their potential as commercial controlled environment crops. Photos courtesy of Genhua Niu, Texas A&M AgriLife Research

With an increasing Asian population in the United States, controlled environment growers have an opportunity to add Asian vegetables to their specialty crop product mix. 

Lettuce, tomatoes and cucumbers are the crops most commonly produced by controlled environment vegetable growers. Other crops that are grown successfully in controlled environment production systems include a variety of leafy greens and herbs. Many CEA growers are looking to expand the product mix they offer their customers and to differentiate themselves from other growers.

One crop that is gaining the attention of controlled environment growers as well as field growers is Asian vegetables. In 2016, researchers at Rutgers University, University of Florida, University of Massachusetts and Penn State University conducted a study of the popularity and feasibility of Asian vegetables among the Asian-American population in New Jersey, Florida, Massachusetts and Pennsylvania. Based on their findings the researchers concluded Asians buy up to three times as many vegetables as white Americans. In addition to determining the Asian population’s vegetable buying habits, the researchers also identified favorite Asian vegetable choices. The researchers used those choices to test 28 cultivars at university plots in New Jersey, Florida and Massachusetts in order to assist growers in focusing on the best crops for their markets.

Expanding customer base

The Pew Research Center, based on U.S. Census Bureau population estimates, reported the Asian population between 2000 and 2019 grew 81 percent during this time span. The population increased from roughly 10.5 million to a record 18.9 million people.

The 2020 United States Census reported approximately 19.9 million people identified as Asian alone in 2020. Including the 4.1 million respondents who identified as Asian in combination with another race, Asian-Americans comprised 24 million people (7.2 percent of the total population). Asians are expected to make up about 40 million of the U.S. population by 2030.

While the focus of the 2016 university study mentioned above focused on Asian vegetables and Asian-American consumers, the researchers also looked at the availability, prices and sales value of these vegetables at Asian grocery stores, farmers’ markets and chain supermarkets. The researchers found other ethnic groups such as white Americans and Latin Americans also purchase and consume a wide assortment of Asian vegetables.

Producing Asian vegetables in Texas

Genhua Niu, professor of urban horticulture at Texas A&M AgriLife Research in Dallas, Texas, is looking at the potential of growing Asian vegetables in both greenhouses and vertical farms. She started her research on Asian vegetables in 2017 when she was working at Texas A&M AgriLife Research in El Paso, TX. In 2018 and 2019 Niu and her colleagues conducted Asian vegetables trials in multiple production systems, including open field, in high tunnels and in greenhouses. The trials were conducted at AgriLife facilities in El Paso, Overton, Uvalde and Weslaco.

The trials included fall and spring plantings to test cool-season varieties of bok choy, tatsoi and Chinese celery, and warm-season varieties of Asian eggplant and yardlong bean.

“The demand for Asian vegetables is increasing due to changing demographics and consumer awareness,” Niu said. “Asian vegetables have been profitable crops in other states, but farmers in Texas aren’t familiar with how to grow them and whether they can be profitable.”

Niu said Texas has the third largest Asian population in the United States behind California and New York-New Jersey. Asian vegetables have been shown to be one of the most profitable crops for producers on the East Coast based on market prices.

“These crops are economically viable,” she said. “Asian leafy vegetables have shorter production cycles and high demand. Many researchers and growers are working on and growing lettuce. We wanted to expand the trials, but included lettuce, tomatoes and cucumbers in our studies. I go to Asian grocery stores all the time and there are always the same Asian vegetable varieties available. Asian retailers and consumers are not happy because the price of these crops is high and variety is limited. This is why there is such a high interest in locally-grown crops. There is an opportunity to increase the number of different Asian crops as well as the varieties.”

Advantages, disadvantages for Texas growers

Niu said the biggest advantage Texas growers have compared to other parts of the United States is the relatively mild winters.

“The temperatures are warmer and the light levels are higher which allows growers to produce more crops with lower heating costs,” she said. “Based on our studies and measurements of natural light levels, growers can produce leafy greens without having to use any supplemental lighting on sunny days. If a grower wants to produce tomatoes or cucumbers more light would be necessary to increase the yields and quality. Growers could use supplemental light with leafy greens which would increase the yields and quality. 

“Texas growers have the opportunity to grow more vegetable crops at lower costs than growers in northern states. Knowing how to market those crops is critical before starting production.”

One major challenge facing Texas greenhouse vegetable growers is warmer summer temperatures.

“Trying to cool the air temperature to optimal levels in a greenhouse is impossible using a common cooling system, such as a combination of evaporative cooling and shade cloth,” Niu said. “Growers who are producing leafy greens during the summer need to be more concerned with chilling the water than cooling the greenhouse air temperature. Growers still need to lower the air temperature during the summer, but cooling down the irrigation water is easier and more important.

“This can be done by either using a chiller to lower the water temperature of an aboveground water reservoir or installing an in-ground water reservoir. Trying to lower the temperature of the aboveground reservoir is going to cost more than lowering the temperature of an in-ground water reservoir. The water temperature should be lowered to at least 75ºF. With an in-ground tank the chiller does not have to run as long to maintain a cooler water temperature.”

For leafy greens production the air temperature should not exceed 85ºF-90ºF.

“Growers can use shading to control the amount of solar radiation coming into the greenhouse,” Niu said.” If growers cannot cool down the water temperature to at least 75ºF during the summer, they will not be able to produce quality leafy greens crops.

“Climate control during the summer is the biggest challenge. High temperature and high humidity can lead to more problems with pests and diseases. Growers need to have the sensors to monitor the environment as well as an environmental control system in order to provide the proper air temperature and humidity. Growers using hydroponic nutrient film technique production systems need to be able to monitor the irrigation system to ensure water is reaching the plants. During periods of warm temperatures it is critical that irrigation water circulates around the plant roots.”

While most of the studies that Niu has conducted have focused on the production of Asian vegetable crops, she is looking to expand her research to include the propagation of starter plants.

“We are planning to conduct studies on propagation for both conventional and organic crop production,” she said. “There is an opportunity for controlled environment growers to produce organic vegetable transplants. 

“The crops we are looking at for propagating organic plug transplants would be for finishing outdoors. Propagating the transplants in a controlled environment gives growers an opportunity to put the plants into the field earlier. The transplants can also be transplanted into 4- or 6-inch pots to increase plant size. These larger starter plants can then be sold to other growers who are looking for larger size transplants.”

Even though Dallas has relatively mild winters there is a concern with frosts or cold temperatures that can kill or damage the plants.

“Transplanting larger size plants into the field can help to finish the crops sooner so that they are ready for market,” Niu said. “Also, growing the transplants for a longer time in the greenhouse for an additional month, allows growers to market a larger transplant that is worth more money.”

For more: Genhua Niu, Texas A&M AgriLife Research, (972) 952-9226; gniu@ag.tamu.edu; https://dallas.tamu.edu/research/urbanagriculture/.

This article is property of Urban Ag News and was written by David Kuack, a freelance technical writer in Fort Worth, Texas.