Freeze unlikely to hurt vineyards

WALLA WALLA – The sudden onset of freezing temperatures can put an end to some late-blooming gardens, but this week’s plunge isn’t likely to harm the Valley’s vineyards.

“I think we dodged the bullet for the most part,” said Jeff Popick, instructor at the Center for Enology and Viticulture at Walla Walla Community College.

Although nighttime lows dropped to 12 to 14 degrees or possibly lower in some areas of Walla Walla County Tuesday night, most vineyards should escape damage, Popick and other growers said.

Popick said the critically damaging temperatures for most wine grape varieties in the Walla Walla Valley are between 8 and 12 degrees.

“It is possible that a couple of the coldest Valley locations at lower elevations near the Walla Walla River came close to that last night (Tuesday), but it would seem unlikely that there was anything other than scattered bud damage here locally – something which can be determined following this event by dissecting bud samples and checking for bud necrosis,” he said.

Chris Figgins of Leonetti Cellar said the sudden drop in temperatures that started Monday had him and others “a little bit worried too, it (was) a pretty quick drop.”

However, he said, “we don’t start seeing damage until it drops to 11-12 degrees. As long as we don’t get into the single digits, we’re not expecting any damage.”

Fortunately, the first hard freeze of the year came after this year’s grape harvest was finished, said Figgins and Duane Wollmuth, executive director of the Walla Walla Valley Wine Alliance.

“The warm October made for a great harvest,” Figgins said.

Wollmuth took a more cautionary tone about possible damage, saying growers might not know until next spring whether their vines suffered any damage.

“In terms of the vines themselves, it’s hard to say,” Wollmuth said. “It’s not always the actual temperature, but how fast it falls.”

Popick said the acclimation process of grape vines in the fall is a function of both decreasing daylight hours and decreasing temperatures. “Ideally, the temperature part of this occurs gradually. … This cold snap, while a bit unnerving, will assist in the process of making our WWV vines more tolerant to future cold spells, which will no doubt occur in the coming weeks.

The next time growers will need to worry will possibly be Saturday night, Popick said. Another shot of very cold air is due to arrive then. If the clouds go away, allowing radiational cooling, and there is a cover of snow to reflect sunlight, temperatures could plunge into single digits that night.

“It will be something to watch,” he said.