Optimizing Winter Spinach Production and Survival In High Tunnels

High tunnels offer a way to extend the local growing season for a variety of crops to meet the demand for local produce.  Winter production in North Logan, Utah (lat. 41.735 N. elevation 1455.45m) may be limited by low temperatures and large diurnal temperature changes as well as exposure to sub-optimal soil temperatures. This project was designed to develop low-cost strategies intended to increase the production levels of spinach grown in the winter in a high tunnel.  A combination of secondary covers (low plastic tunnels and fabric row cover) and heating cables help resolve temperature-related growth problems experienced in the winter.  Both low tunnels and row covers significantly increased production levels (leaf number, leaf area, specific leaf weight) when compared to the uncovered control. Spinach grown under low tunnels had significantly higher production levels than when grown under row covers.  The addition of soil heating cables further increased total yield in all cover treatments but there was no significant interaction between heating cables and secondary covers.  A combination of heating cables and low tunnel achieved the highest average yield, and would be the optimal method for maximizing winter spinach yields in high tunnels in a high elevation arid climate.