2019 ASHS Annual Conference

High tunnels have enabled North Dakota growers to initiate production much earlier in the spring when compared to filed production. A field study was conducted at the North Dakota State University Horticulture Research Arboretum to evaluate the influence of three soil heating treatments (no heat, soil heating coils, and infrared heat mats) and three low tunnel coverings (clear plastic, 1 oz. and 2.5 ounce frost blankets) on the growth and production of two basil cultivars (Elenor and Everleaf) and two snap bean cultivars (EZ Pick and Amethyst Purple) when transplanted or seeded at three timings (T1=April 9, T2=April 30, and T3=May 21). Low tunnel coverings were used on the first timing only and remained over plots until April 30. The soil heating cables and infrared heating mats had internal thermostats set to shut off when soil temperature reach 75 F and thus were used until the end of the experiment. Dataloggers were used to record soil and air temperatures every 30 minutes. Thermistors were placed at the 6-inch height within a treatment row and at a 4-inch dept in the soil within the row to record treatment differences. In general, the clear plastic low tunnel resulted in higher daytime air temperatures, especially on sunny days, while the soil heating with row covers resulted in slightly higher air temperatures at night. The greatest snap bean yield occurred when seed were planted T1 with soil heating cables. This yield was greater than yields for beans seeded T1 no heat, and bean planted T3 regardless of the heat source. The greatest basil yield occurred when transplanted T1 with soil heating cables. This yield was greater than yields for basil from all other timings and heat sources. Future research will examine other cold sensitive vegetables as well as economics related to even earlier transplanting or seeding schedules.