Vintners along California’s Central Coast are evaluating their vineyards after one of the worst frosts in years struck the area’s wine regions last month. For two nights beginning April 8, temperatures dropped as low as 24° F in some areas and stayed below freezing for several hours. The cold damaged vines by killing the tender shoots and leaves, just as many buds were starting to sprout. The Paso Robles area was hit the hardest, with some growers estimating that the damage could have a severe impact on the size of the 2011 crop.
“I’ve never seen anything like it in Paso before,” said Gary Eberle, owner of Eberle winery in East Paso Robles. Eberle, who has made wine in Paso since 1973, reports that the frost caused widespread damage with some vineyards completely wiped out. One of the vineyards he usually buys Sangiovese from probably won’t have a pickable crop this year.
Stacie Jacob, executive director at the Paso Robles Wine Country Alliance, says that some of the area’s top viticulturists are estimating that the crop loss could range between 30 and 50 percent. “The frost was the most severe the area has experienced in the past decade,” she said. But other winemakers told Wine Spectator they estimate that the figure could be as low as 15 percent. It may be several months before the extent of the damage is clear.
The frost was particularly devastating because there was no inversion layer. Cold weather with an inversion layer has cool air on the bottom and warmer air above it. Wineries often protect against frost damage by placing wind machines in their vineyards to pull down warmer air to protect the vines. But this is ineffective if there is no inversion layer. Another method is to spray the vines with water, which traps warmth close to each plant's surface as it freezes, but not everyone has sprinkler systems in their vineyards.
The cold was indiscriminate in Paso. In frost conditions, the cold weather usually sinks into the lower portions of the vineyards, but with no inversion layer some of the vineyards on the hilltops were damaged too. Eberle noticed that vineyards on both the east and west sides of Paso Robles were hit.
The extent of the damage varied between vineyards and varietals. Justin Smith, winemaker at Saxum, says his vineyards were experiencing a very late budbreak and his Syrah and Mourvèdre hadn’t broken bud when the frost hit. “The primaries have budded out now and seem untouched,” he said. Early ripening grapes such as Chardonnay and Pinot Noir were more susceptible to the frost. “The Grenache got hit the worst because it opened the earliest,” said Smith.
While Paso was hit the hardest, winemakers farther north in Monterey County are reporting damage as well. “There were some pockets in the Arroyo Seco,” said Dean De Korth, winemaker at Bernardus in the Carmel Valley. Bernardus turned on the sprinkler systems at its estate vineyards during the cold front. But most of the Monterey County growing region was relatively unaffected. “We don’t seem to have nearly the damage they have farther south,” he said.
Winemakers are reporting a similar situation in Santa Barbara County. Most of the region dodged the worst of the weather. “It sounded like the vineyards we source from are pretty much OK except for a little damage,” said Brian Loring of Loring Wine Company, who buys grapes from vineyards in Sta. Rita Hills and Sta. Maria Valley.
It’s still too early to determine how the frost will affect the 2011 harvest in Paso Robles. Vintners are waiting to see how the secondary buds react and others are shoot thinning in their vineyards. While the crop will undoubtedly be reduced, some winemakers are remaining positive about the quality of the grapes. “Maybe mother nature did some of our crop thinning this year,” said Cris Cherry of Villa Creek Cellars in Paso. “If we get a decent set from our second growth, we could walk into a great vintage.”