High Tunnel and Field System Comparison for Spring Organic Lettuce Production in Georgia

High tunnels may help mitigate unfavorable climate and weather on lettuce (Lactuca sativa L.) production leading to greater yields and quality, yet information for using these systems in the Southeast region is lacking. This study evaluated the effect of high tunnels and three planting dates (PDs) (early March, late-March, and mid-April) on spring organic lettuce production. A 25% to 36% increase in marketable fresh weight for butterhead and romaine lettuce, respectively, was observed under high tunnels compared with the field in 2016, but there was no difference among the two growing systems in 2015. High tunnel lettuce was harvested approximate to 2 to 7 days earlier than in the field in 2015 and 2016, respectively. Pest and disease pressure (e.g., Sclerotinia sclerotiorum) as well as the incidence of physiological disorders (i.e., bolting, tip burn, and undersized heads) were similar between the two systems indicating that our high tunnel system did not provide a benefit for these issues. High tunnel air temperatures were approximate to 3 to 5 degrees C greater on the coldest mornings and only 1 degrees C greater on the warmest days compared with the field. Average relative humidity (RH), leaf wetness, and light levels were all lower under the high tunnels. Our results indicate that high tunnels can help increase the production of spring organic lettuce in Georgia, but that the advantage may depend on yearly weather conditions.