Frost Protection for Texas Grapes
During a recent trip to the Texas High Plains, a major topic of conversation with grape growers was the concern over spring frosts and the methods available to mitigate freeze damage to young vine tissue and grapes. Texas in general, especially the High Plains, is noted for turbulent and unpredictable weather that often brings frigid temperatures soon after bud break when grapevines are most susceptible to frost damage. Four methods of commonly used frost protection are described below. Please note that none of these are fool-proof, and all are expensive, unfortunately adding cost to Texas grapes, and therefore to Texas wines.
Wind machines are now being installed in many Texas vineyards. These two-blade fans are mounted on a column and are driven by a motor that runs on diesel, gasoline, natural gas or propane. The fans are designed to rotate in a circular pattern, pushing warmer air from above the vineyard down into the grapevines. Remember that warm air rises and cold air sinks, so when frigid weather occurs, it will be colder down low near the fruiting zone of the vines. These wind machines turn on automatically when the temperature reaches a selected set-point, usually just below freezing. Each machine is designed to protect a certain area within a vineyard. A grouping of machines is required to protect larger vineyards. If the vineyard is on a slope, machines are set to push cold air downhill. As you visit Texas vineyards, you will likely see these wind machines standing ready to protect our state’s precious grape crops.
A wind machine that runs on propane. Photo from the Orchard-Rite website
A frost protection furnace is another tool being used by Texas grape growers. These furnaces burn fuel, usually propane, to heat air that is blown into the vineyard through a