Four Growing Seasons in High Tunnels

Over the course of four years we studied crop growth and yields in two high tunnels. The tunnels are oriented perpendicular to one another, one on an east-west axis, the other north-south. Each tunnel is 3.7 x 4.9 m, with a central aisle and roll-up sides for ventilation. We grew fresh cut sunflowers in 2012; basil, chives, marjoram, and oregano in 2013 and 2014; and chives in 2015. Fresh cut sunflowers showed longer stem lengths when grown in the north-south tunnel (103 to 157 cm, depending on cultivar) than those grown in the east-west tunnel (104 to 118 cm, depending on cultivar). There were no differences, however, in days to harvest between the two tunnels, ranging from 77 to 95 days, depending on cultivar. Fresh market herbs showed differences depending on species and year. Basil total fresh weight was highest in the east-west tunnel in 2013 (mean 196 g per plant) but highest in the north-south tunnel in 2014 (mean 285 g per plant). Oregano fresh weight was highest in the north-south tunnel both years (mean per plant 234 g in 2013 and 213 g in 2014). Like basil, marjoram fresh weight was highest in the east-west tunnel in 2013 (mean 229 g per plant) but higher in the north-south tunnel in 2014 (mean 289 g per plant). Chives fresh weight was highest in the east-west tunnel both years (mean 31 g in 2013 and 80 g in 2014). Chives in 2015 showed greatest fresh weight when grown in the north-south tunnel (mean 49 g per plant) as opposed to the east-west tunnel (mean 44 g per plant). There were also differences among the four locations within the tunnels over the four years: east and west sides of the central aisle in the north-south tunnel and north and south sides of the aisle in the east-west tunnel. These differences indicated the east exposure in the north-south-oriented tunnel was generally most favorable for production of the crops grown.