Smudge Pots

Water, Wind and Fire Fight Off Frost

After three weeks of nearly non-stop rainfall, it might seem strange to wake up and see sprinklers going off all over the Valley. Counterintuitively, those sprinklers are protecting the just-bursting buds from early-spring frost invasion.

According to Tom Hsieh (pronounced shay) of Hanson-Hsieh vineyard in Oak Knoll, the water creates a layer around the bud — a blanket if you will — that freezes instead of the delicate bud tissue. Most vineyards have an alarm that goes off if the temperature drops below 40 degrees Farenheit, either turning on the sprinklers or irrigation automatically or dragging the farmer out of bed to do so.

Wind is also pretty effective. Those giant fans you see high above the vines, unused most of the time, are instrumental this time of the year for moving frosty air out of the vineyard. Wineries for whom money is no object, such as Agustin Huneeus’ Napa Valley outpost, Quintessa, may hire helicopters (yes, helicopters) to hover over the vineyard in the early morning hours (so that’s why the wine costs $145 a bottle).

Smudge pots (such as the ones pictured below), were developed for the fruit orchards in Southern California in 1913. (This one, spotted at Chase Cellars, looks as though it might have actually been one of the originals.) More important than raising the temperature (which they do only slightly) smudge pots create air convection currents, according to Jancis Robinson, mixing warmer upper air with cold air that has settled closer to the ground.

This week’s lows, throughout Napa and Sonoma, are not expected to drop below 42 degrees Farenheit. But cautious farmers with reservoirs full of water will likely continue to sprinkle, just in case.

(click to enlarge)