Container production of ornamental crops in retractable roof greenhouses in semi-arid climate of the southwestern United States

Retractable roof greenhouses (RRGH) offer nursery growers in the semi-arid climates of the Southwestern United States protection from high temperatures and radiation in summer and from cold temperatures in winter with the option of growing in a full sun environment when environmental conditions are favorable. Environmental conditions such as PAR, air, leaf, and media temperatures, and responses of herbaceous and woody ornamental plants growing in containers in RRGH or other environments were monitored during different seasons in Arizona. Conditions inside RRGH were compared to plastic tunnels, stationary shade houses, and full sun environments. In winter, RRGH provided frost protection similar to plastic tunnels and maintained minimum air and media temperatures several degrees above freezing when air and media temperatures outside reached -2°C and 0°C, respectively. Water use of high and low water use ornamental plants was studied under different environments and varied by environment, species, container size and day.