Paul Bush of Madrona Vineyards on Apple Hill in El Dorado County sent down this photo as a followup to an item I posted last week (see below) on the threat that freezing spring temperatures could pose to this year's wine grapes because of an unusually early start to the growing cycle. Sure enough, the nighttime temperature on Apple Hill dipped below freezing a week ago, to 29 degrees. By the looks of this photo, young and vulnerable buds on vines were frozen stiff, and thus extensively damaged if not killed.
But appearances can be deceiving. As the temperature dropped, Bush turned on his vineyard's first line of defense against a destructive freeze, a sprinkler irrigation system. The water warms the vines and the soil underneath, helps conduct that heat through canes and buds, and encloses the young growth with a thin sheath of ice that protects it from the chilly air while trapping the plant's heat. It may look goofy, but the technique generally shields the new growth from extensive damage, as it did for the most part at Madrona Vineyards, reports Bush. "And now we wait for the next frost event," adds Bush, indicating he won't be straying far from his temperature gauges and sprinkler switches for the next several weeks.