2016/2017 Spinach Trial Temperature Data (up to Jan 31, 2017)
Winter spinach production in unheated high tunnels typically involves a harvest in December, a long dormancy period, and then a late-winter and early-spring flush. The purpose of these trials is to evaluate the yield response when adding a little heat and 12 hours of supplemental light. At each of three locations we installed three low tunnels within the high tunnel. All three low tunnels are covered with frost blanket. One low tunnel receives no supplemental heat, one low tunnel is heated to maintain a minimum temperature of 32F, and one low tunnel is heated to maintain a minimum temperature of 45F. For this trial we are heating with forced air from an electric space heater. Half of each high tunnel also receives 12 hours of LED light.
The photo to the right shows the low tunnels at the Washburn High Tunnel. The heated low tunnels receive heat from an electric space heater with forced air blown down the length of the plastic tube. The low tunnels are covered with frost blanket to hold the heat. It is important to note this heating system is used in order to conduct the experiment and may not be the best system for expanded commercial production.