Dr. Steven Guldan
2016 - 2019

Jose Fernandez Memorial Chair Final Report

Year-round Production of High Value Crops Using High Tunnels

There is great interest in using high tunnels (commonly called hoop houses) for season extension and winter production of high value crops. For example, the Santa Fe Farmers Market has become a year-round market that requires produce during the winter months. In addition, new marketing initiatives/programs are developing in which schools and other public institutions are encouraged to purchase fresh produce from local farmers. To develop and take advantage of these markets, however, requires that farmers be able to reliably and cost-effectively produce product during the late fall, winter, and early spring months, as well as during the normal growing season. Little research data, however, had been available on using high tunnels in New Mexico.

The goal of the research supported in part by the Jose Fernandez Chair is to develop year-round, intensive, high-value production systems. Optimizing year-round production is not that straightforward as trade-offs have to be evaluated. For example, for a given high tunnel, planting spinach in the tunnel at the appropriate fall date for maximum January yields might mean terminating a late-summer/fall vegetable crop that is using/benefitting from the tunnel for fall season extension. High tunnels can be used to maximize use of water, sunlight, and space/land resources. This research can be especially useful for small-scale producers, but can also be scaled up for larger operations.

The Jose Fernandez Chair allowed increased support for the Alcalde Sustainable Agriculture Science Center research team and collaborators to further develop year-round cropping through use of high tunnels. Through partial support of staff, a graduate student, supplies, publication charges, soil tests, and travel, the Jose Fernandez Chair has contributed to the following:

Graduate Student

Jacqueline Cormier was supported in part by Jose Fernandez Chair funds and carried out her master’s degree research at the Alcalde Sustainable Agriculture Science Center. Her major advisor was Ivette Guzmán and the title of her thesis was “Intercropping Winter Greens Between Blackberry Rows for Year-Round High Tunnel Production.”


Please visit https://aces.nmsu.edu/aes/fernandezchair/publications-sponsored-b.html for publications from the high tunnel research project supported in part by the Jose Fernandez Chair.

  • Heyduck, R.F., D.M. VanLeeuwen, and S.J. Guldan. 2020. Effect of harvest schedule on organic kale grown during the winter in high tunnels. HortTechnology 30:570-575. DOI: https://doi.org/10.21273/HORTTECH04584-20.
  • Uchanski, M.E., D.M. VanLeeuwen, S.J. Guldan, C.L. Falk, M. Shukla, and J. Enfield. 2020. Temperature and light characterization during winter production season in high tunnels in the southwestern United States. HortTechnology 30:259-267. DOI: https://doi.org/10.21273/HORTTECH04486-19.
  • Cormier, J., R. Heyduck, S. Guldan, S. Yao, D. VanLeeuwen, and I. Guzman. 2020. Intercropping winter greens between blackberry rows for year-round high tunnel production. HortTechnology 30:47-54. DOI: https://doi.org/10.21273/HORTTECH04436-19.
  • Yao, S., S. Guldan, and R. Heyduck. 2019. High tunnel apricot production in frost-prone northern New Mexico. HortTechnology 29:457-460. DOI: https://doi.org/10.21273/HORTTECH04315-19.
  • Heyduck, R.F., S.J. Guldan, and I. Guzman. 2019. Effect of sowing date and harvest schedule on organic spinach grown during the winter in high tunnels. HortTechnology 29(3):320-329. DOI: https://doi.org/10.21273/HORTTECH04257-18.
  • Yao, S., S. Guldan, and R. Heyduck. 2018. Organic blackberry cultivar trials at high elevation and in high pH soil in the southwestern United States. J. American Pomological Society 72(3):202-209. http://www.pubhort.org/aps/72/v72_n3_a7.htm.

Field Days

A special topic field day on winter production in high tunnels took place in January 2018
2018 Winter Greens Field Day Flyer
In addition, project work was presented at Alcalde Center regular field days on August 11, 2016, and August 10, 2018
2016 Field Day Flyer
2018 Field Day Flyer

Brief Summary of Results
(Detailed results are presented in the journal articles in the Publications section.)

Temperature and Light in High Tunnels during Winter

NM, and a northern site in Alcalde, NM, to characterize the crop environment in three high tunnel designs during the winter growing season (October–March). High tunnels were 16 × 32 ft. Heavyweight woven plastic covered a single-layer (SL) high tunnel design. Double-layer designs (DL) were covered with a lightweight woven plastic on the bottom, followed by a second layer of the heavyweight plastic inflated with a fan. A heat sink was created using 16 55-gal barrels painted black, filled with water, and aligned along the north side of the double layer for the DL+B design. Soil temperature (3 inches deep) and air temperature (1 ft above the soil surface) were recorded inside the high tunnel under a floating row cover, and outside the high tunnel. In addition, photosynthetically active radiation (PAR) was recorded in and around the high tunnels during or near the winter solstice each year of the study. High tunnels greatly modified the environment to allow for production of winter-hardy vegetables during the coldest months in New Mexico. During January, for example, monthly average maximum air temperature, averaged across high tunnel designs, was 40 °F higher in the high tunnel under the row cover than outside for Alcalde and up to 36 °F higher in Las Cruces. January monthly average minimum air temperatures, averaged across high tunnel designs, were up to 22 °F higher in high tunnels than outside in Alcalde and 18 °F higher in Las Cruces. Daily air and soil temperature minimums were highest in the DL+B design and lowest in the SL design. Maximum air and soil temperatures did not significantly differ between high tunnel designs, although the DL+B design measurements were consistently lower. During season 1, the SL design had significantly higher PAR transmission than the other two designs. In the northern location, the difference became insignificant during seasons 2 and 3, likely due to dust accumulation and aging. In the southern location, the SL design maintained higher PAR transmission throughout the study, possibly due to cleaning.

Kale and Spinach Production in High Tunnels during Winter

We examined the effect of harvest schedule on the yield of Red Russian kale grown during the winter for two seasons in 16 × 32 ft high tunnels at Alcalde, NM. All plots were sown on 16 Oct. and harvested four times according to four harvest schedules: A) 8, 16, 20, and 24 weeks after sowing; B) 10, 17, 21, and 25 weeks after sowing; C) 12, 18, 22 and 26 weeks after sowing; and D) 14, 19, 23, and 27 weeks after sowing. The first harvest of each treatment was the greatest, averaging 216 g/ft2, compared to 88, 109, and 104 g/ft2 for harvests 2, 3, and 4, respectively. Considering the entire 240-ft2 cropped area of the high tunnel, staggered harvests of 60 ft2 at a time can yield 2.6 to 17.5 kg per harvest or up to 124 kg over an entire season. Although we examined the yield of mature leaves, harvests could possibly begin earlier than in this study for “baby” kale or salad mixes, and the area harvested could be tailored to plant growth stage and market demand. In a two-part study, we examined the effect of sowing date and harvest schedule on the yield of Bloomsdale Long Standing spinach grown during the winter in 16 × 32 ft high tunnels at Alcalde, NM. Each part of the study was conducted for two growing seasons. In study A, spinach was sown four times at roughly 2-week intervals (mid-October, early November, mid-November, and early December) and data was collected for three harvests in mid-January, mid-February, and mid-March. The earliest sowing date had the least-dense stands, and plant density increased with each subsequent sowing. The two earliest sowing dates had significantly higher season-long yield than the later two sowings. In Study B, all plots were sown in mid-October, but harvest schedule treatments were staggered such that harvests began at 9, 11, 13, or 15 weeks after sowing and continued at irregular intervals. Treatment 2, with harvests beginning after 11 weeks, had the greatest season-long yield, slightly greater than when harvests began at 9 weeks, and significantly more than when harvest began 13 weeks or later. Overall, we found that a staggered harvest schedule can provide spinach weekly for direct marketing opportunities.

Blackberries in High Tunnels

Two semi–erect, three erect floricane-fruiting, and one primocane-fruiting blackberry cultivars were evaluated in high tunnels and in the field at Alcalde, NM. Semi–erect cultivars Triple Crown and Chester Thornless were planted at 5 × 8 ft in a 16 × 40 ft high tunnel with an identical field planting. Erect cultivars Ouachita, Natchez and Navaho, and primocane-fruiting cultivar Prime-Ark® 45 were planted at 2 × 5.6 ft in another 16 × 40 ft high tunnel with an identical field planting. We found that high tunnels advanced the blackberry harvest season for both semi–erect and erect cultivars by one to three weeks, and extended the harvest season of the yields in high tunnels than open field.

Blackberry-Winter Green Intercrop in High Tunnels

At Alcalde, NM, a study was carried out that intercropped Red Russian kale and Bloomsdale spinach as a winter crop between rows of Chester Thornless and Triple Crown floricane fruiting blackberry. Blackberries were planted at 5 × 8 ft in a 16 × 40 ft high tunnel with an identical field planting. In the high tunnel blackberries, kale and spinach were direct seeded in three rows at the base of either side of the two rows of dormant blackberry canes in mid-October. We found that the high tunnel environment for winter greens growth was satisfactory; however, closing the high tunnel during the winter for the greens was detrimental for berry canes, apparently because they did not receive adequate chilling hours resulting in cane and bud damage. More research is needed to determine if high tunnel venting at appropriate times can be managed to optimize chill unit accumulation for blackberries while still providing an environment for winter greens growth.

Apricots in High Tunnels

Apricot trees flower earlier than other traditional fruit trees in northern New Mexico, making them extremely vulnerable to late frosts. An open field planting at Alcalde, NM, did not produce any harvestable fruit from 2001 through 2014. In 2012, we planted several cultivars of apricots in two 16 × 40 ft high tunnels. Trees were trained to a spindle system in one high tunnel and an upright fruiting offshoot (UFO) system in the other, and there were identical plantings in the open field for each high tunnel. Supplemental heating was provided in the high tunnels starting at blooming time. A heating device is necessary for high tunnel apricot fruit production in northern New Mexico because trees normally bloom in early to late March, depending on the year, while frosts can continue until mid-May. In 2015, relatively high yields were obtained from all cultivars. On average across all cultivars, the UFO system produced 60% of the yield of the spindle system in 2015. In years such as 2017 and 2018 with temperatures dropping below 10 °F in late February/early March, some of the expanded flower buds were killed before bloom. On those cold nights, one 100-lb tank of propane may or may not be enough for one night’s frost protection, clearly making it uneconomical in those years. We conclude that only in years with a cool spring, late-blooming trees, and mild temperatures in April and May can high tunnel apricot production generate positive revenue with high, direct market prices. High tunnel apricot production with heating devices is still risky and cannot guarantee a reliable crop in northern New Mexico or similar areas.

Other Studies

Jose Fernandez Chair funds also assisted to begin high tunnel studies of summer cucumber production and soil health building through use of cover crops and minimum tillage.