Protecting Our Vineyards From Frost

Posted By Don Sumner on Feb 20, 2015 |

After getting about nine inches of rain during the last story, our crews are finally back out in the vineyards, finishing up the pruning they began before the storm moved in.

Our winter pruning season takes place over an extended period of time, and pruning will guide the vines in certain directions and for the particular purposes best suited to each varietal.

This season, our challenge will be the weather, which is warming earlier than usual. That means that our vines—while not yet budding, but still showing signs of moving in that direction—will be susceptible to any heavy frosts that come along, later in spring. Frost and wind are concerns at this stage of development. When there is danger of frost, traditional steps taken to protect the tender young shoots include the use of large fans to circulate the cold air, sprinkling the vines with water to coat them in a blanket of protective ice, and using  heaters to warm the air temperature in the vineyard.

When water freezes, heat energy is released. Sprinklers use this concept to keep vines at a safe temperature by creating ice on the vines and water dripping off the ice. If there is no water dripping off the ice, then too little water is being applied, and the sprinklers may actually be causing more harm than the frost event.

We use sprinklers in our vineyards, but they only protect the vines down to about 23 degrees, so if there’s a below-freezing cold snap, our vineyards’ tender new shoots will die.

We’ll be keeping a close eye on local temperatures, humidity, dew points, and wind speeds, to calculate when to use our sprinklers to protect the 2015 vintage. Wish us well!