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Sub-freezing temperatures don’t concern Washington wine grape growers

By Andy Perdue on December 7, 2013

Frost clings to a sign in a Washington state cabernet sauvignon vineyard.

Frost clings to a sign in a vineyard on Washington’s Red Mountain. Temperatures are expected to drop into single digits this weekend in Washington wine country. (Photo by Andy Perdue/Great Northwest Wine)

As the weather in Washington wine country gets downright frightful, wine grape growers are keeping a close eye on the health of their vines.

But most aren’t too worried at this point.

“I haven’t seen any numbers that concern me,” said Kevin Corliss, director of vineyard operations for Ste. Michelle Wine Estates, which uses two-thirds of all the grapes in Washington. “I’m watching them like a hawk. Everything is staying above zero.”

According to Washington State University, the most tender variety in Washington wine country – Petit Verdot – won’t sustain any kind of bud damage until temperatures dip below zero. Important varieties will be able to handle even colder temperatures:

Cabernet Sauvignon: minus-7.5 Fahrenheit
Merlot: minus-5
Syrah: minus-3.5
Riesling: minus-7
Chardonnay: minus-7.5

Weather forecasts put lows in the Yakima Valley at 7 degrees above zero Saturday night and warming up to lows above freezing by midweek. In the Walla Walla Valley, temperatures could reach as low as 5 degrees above zero.

No worries in Walla Walla, Columbia Valley

Wine grapes get a layer of frost in Washington wine country.

A few leftover grapes pick up specks of frost in the Yakima Valley. (Photo by Andy Perdue/Great Northwest Wine)

Norm McKibben, who owns and manages several vineyards in the Walla Walla Valley and owns Pepper Bridge Winery, is unconcerned.

“The cold is not hurting us a bit,” he said. “In fact, if it stays above zero, it helps the vines harden off (for winter). Right now, I’m happy.”

McKibben said wind chill doesn’t affect grapevines, so even if the wind causes the air to feel colder, it won’t hurt the vines.

Kent Waliser, general manager of renowned Sagemoor Vineyards along the Columbia River north of Pasco, checked some vines in a cold area of one of his vineyards after the first cold snap last week.

“We didn’t see any problems,” he told Great Northwest Wine. “We think we’re just fine.”

But that doesn’t keep him from being diligent about watching the weather forecasts.

“We’re always concerned because cold weather at the wrong time is one of the risks we face with grapes in Washington,” he said. “It always makes you nervous, but I think we’ll skate by.”

Winter hurts Washington wine country every 5-8 years

Washington wine country vineyards are cold.

Temperatures on Washington’s Red Mountain dipped into single digits Friday morning. (Photo by Andy Perdue/Great Northwest Wine)

Every five to eight years, Washington’s Columbia Valley deals with a winter weather event that can damage vineyards. Typically, this happens when temperatures rise to an unseasonably warm level, such as 60 or 70 degrees, then plummets below freezing. The warm temperatures signal the vines to wake from their winter slumber, which gets sap flowing. Then the following cold snap can cause mild to catastrophic damage to different parts of the vine.

In 1996, sustained cold temperatures caused widespread damage to Washington vineyards, with more than 40 percent losing their entire crop. In 2004, the Walla Walla Valley was hit hard, losing as much as 80 percent of the vineyards for a year. The most recent event was in November 2010, when temperatures dropped to minus-6 in the Horse Heaven Hills. Many vineyards, including Champoux, Coyote Canyon and Andrews suffered heavy damage.

Waliser doesn’t expect this kind of damaging event because temperatures since late October have dropped steadily, giving vines the opportunity to prepare for winter by becoming dormant.

He is mildly concerned about an acre of Grenache he planted this year. Because it’s so young and is a tender variety, the vines are more susceptible to sub-freezing temperatures.

“Those kinds of plants get kind of beat up because they’re young,” he said.

Todd Newhouse, a third-generation grape grower on Snipes Mountain near the Yakima Valley town of Sunnyside, hasn’t checked his vines for damage but isn’t too concerned.

“Most varieties should still be OK until the temperatures get down below zero,” he said. “I’m optimistic.”

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About Andy Perdue

Andy Perdue is the editor and publisher of Great Northwest Wine. He is a third-generation journalist who has worked at newspapers since the mid-1980s and has been writing about wine since 1998. He co-founded Wine Press Northwest magazine with Eric Degerman and served as its editor-in-chief for 15 years. He is a frequent judge at international wine competitions. He is the author of "The Northwest Wine Guide: A Buyer's Handbook" (Sasquatch, 2003) and has contributed to four other books. He writes about wine for The Seattle Times. You can find him on Twitter and Google+.