Season Extenders, like floating row covers and grow tunnels, can delay freezing of the soil and create a warm environment for plant growth. Row covers are a great way to extend lettuce and spinach season in the fall. In some areas, using Season Extenders for vegetables means that gardeners can pick greens into winter. For those wanting to get an early start on spring gardening or extend the fall season, our Polythene Grow Tunnel helps create a warm, humid environment for plant growth.