2017 ASHS Annual Conference

The productivity of high tunnel and field grown specialty cut flower cultivars needs further evaluation for all regions of the United States, including the Northern Great Plains. This project compared cultivars of Antirrhinum majus L. (‘Potomac White’ and ‘Rocket Mix’), Delphinium x elatum D. (‘Guardian Mix’ and ‘Pacific Giant Mix’), Eustoma grandiflorum Calib. (‘Double ABC 2 Blue’, ‘Double Echo Blue’ and ‘Double Mariachi Misty Blue’), and Dahlia × hybrida Cav. (‘Karma Irene’ and ’Karma Chocolate’) in high tunnel and field environments in Williston, North Dakota. The Williston Research and Extension Center is located at latitude 48 9.9’N and is one of the northernmost high tunnel research centers in the United States outside of Alaska. In 2016, the site experienced a 118-day growing season. The project evaluated transplanting at two different soil temperatures, 14 and 19 °C to assess early season extension, morphological traits, and productivity. Data from the first season shows that soil temperature in the high tunnel had a significant effect on stem caliper. The 14 °C soil planting temperature had an average of 5.5 % increased stem caliper compared to the 19 °C planting temperature for all species. Soil temperature also had a significant effect in the high tunnel on total stems per 3-week harvest period for Antirrhinum cultivars. The 14 °C soil temperature averaged 12.5 stems per period in comparison to 5.1 stems per period for 19 °C soil temperature, a nearly 250 % increase. Significant cultivar differences were observed independent of temperature for Antirrhinum and Dahlia within both the high tunnel and field plots. Cultivar differences were observed for Delphinium and Eustoma only in the high tunnel environment. The results of this study suggest that certain cultivars are better suited to production in high tunnels while others showed no environment preference.