High tunnel production had top billing at the recent Arkansas-Oklahoma Horticulture Industries Show held in Fayetteville, Arkansas, in January. NCAT’s Horticulture Specialist Luke Freeman helped lead a pre-conference tour of high tunnels at the University of Arkansas Research Farm on Thursday, January 3. Several presenters discussed high tunnel fruit and vegetable production during the conference sessions on Friday and Saturday, January 4 and 5.
High Tunnels: The What and Why
High tunnels are unheated greenhouses with a metal frame covered in plastic. Growers use high tunnels as a cost-effective way to modify the environment for producing specialty crops. The increased temperatures in a high tunnel can allow vegetable growers to plant crops 3 to 4 weeks before crops are planted in the field. High tunnels’ warmer temperatures also protect crops from frost in the fall, allowing growers to extend the harvest an additional month.
The protection from wind and rain in a high tunnel also reduces disease pressure and environmental stress. Table grapes grown in a high tunnel can be produced with around one-quarter the amount of fungicide sprays that grapes in the field would need in order to make a crop. And thanks to the warmer temperatures and protection from environmental stress, strawberries produce much higher-quality, larger berries in a high tunnel.
High Tunnel Tour Highlights
The high tunnel tour on Thursday featured the University of Arkansas’s research on high tunnel grape and strawberry production, along with a high tunnel vegetable planting date demonstration. Jim Shaw of Cedar Farm in Sand Springs, Oklahoma, kicked off the tour by demonstrating walk-behind tractors for soil work in the high tunnel. Because walk-behind tractors are lightweight and maneuverable, while still having enough horse-power to operate PTO implements, they are ideally suited for soil work in high tunnels. Jim demonstrated how to use the rotary plow to make a raised bed in the high tunnel, which can be finished off with a tiller or power harrow to create a level seed bed.
Dr. Amanda McWhirt, the Fruit and Vegetable Specialist for Arkansas Extension, discussed findings from a vegetable planting date trial in one of the high tunnels at the farm. Researchers planted broccoli, kale, spinach, and lettuce in the tunnel at various planting dates during the fall of 2018. They covered some plots in row cover and left black plastic mulch off of other plots. The results from the broccoli planting were especially striking. The broccoli planted first, on October 3, were starting to form heads. The broccoli planted a week later, on October 10, were significantly smaller with almost no florets developed. The broccoli under row cover were also noticeably larger than the broccoli that had not been covered.
U of A horticulture graduate student Karlee Pruitt discussed her research on high tunnel strawberries. Strawberries planted in high tunnels in September can come into production as early as the following February, depending on the severity of the winter. The warmer temperatures in the high tunnel will cause the strawberries to bloom earlier—late winter or early spring—so protecting the flowers from frost with row cover during cold nights in January and February is critical. Certain pests such as spider mites and aphids can be more problematic in the high tunnel because of the closed environment, so it is important to stay diligent in scouting for insect pests.
Horticulture professor Dr. Elena Garcia discussed the high tunnel grape research she is leading at the U of A. Table grapes planted in high tunnels come into production in 1 to 2 years, compared to the 3 to 4 year timeline for grapes planted in the field. In addition, high tunnel grapes’ yield can be as much as three times the yield of field grapes. The additional yield more than pays for the cost of the high tunnel after a few years of production. One challenge with grape production in high tunnels is that the vigorous vine growth can be difficult to control, leading to a dense canopy that shades out the fruit. The U of A team has been studying best practices for grape canopy management in the high tunnel, with summer pruning and leaf removal as options.
Luke is working with Dr. Garcia to publish fact sheets on high tunnel grape production, which will be available on the ATTRA Sustainable Agriculture website. ATTRA has several publications currently available on high tunnel production, including High Tunnel Tree Fruit and Grape Production for Eastern Growers. You can also find videos on high tunnel grapes, produced in partnership with the U of A, on NCAT/ATTRA’s YouTube channel. If you’re interested in other types of fruit production, you can listen to our podcast episode on growing brambles in high tunnels.
If you have questions about high tunnel vegetable or fruit production, remember our agriculture specialists are just a phone call or email away! Contact us 1-800-346-9140 or email firstname.lastname@example.org.