Season Extension and Sugar Accumulation in Low Tunnel-grown Spinach

Season extension allows growers to continue the growing season through late fall and begin in early spring. This experiment tested the hypothesis that by using season extension in conjunction with organic and sustainable farming practices, spinach crops would be sweeter by containing higher sugar content and, therefore, would be preferred over conventionally grown plants. Spinach is a cold weather crop that has evolved an osmotic antifreeze system in which high sugar concentrations prevent death in harsh winter conditions. The sugar concentrations of store-bought spinach were compared to those of spinach grown through the winter months in two low tunnels and in cold temperature growth chambers. In addition to analyzing the sugar content, the internal temperature of the tunnels was monitored and analyzed in comparison to the outdoor temperature. Our results suggest that low tunnels can reach temperatures of more than 30°F greater than outdoor temperatures, consistently reach warmer average daily temperatures, and yield spinach crops with higher glucose concentrations.