NEWBERG, Ore. — As grape harvest season rapidly approaches, the weather and conditions in the final weeks could be the difference between an award-winning vintage and a tainted vintage.

With the triple-digit temperatures last week into this week, the Willamette Valley’s grapes are at risk of shriveling into raisins before being pressed, fermented, and conditioned.

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But some area wineries are taking steps to prevent that from happening. 

Hazelfern Cellars, a Newberg winery at 4008 N.E. Zimri Drive, is utilizing a strategy to combat the heat: spraying the vines with a natural, organic white clay mixed with water, according to Bryan Laing, winemaker at Hazelfern since 2006. The clay acts like sunscreen for the grapes.

“That white clay is going to help reflect UV light away from the grapes and leaf canopy, minimizing sunburn and raisining,” Laing told Newsberg. “We sprayed clay this week to protect the grapes heading into this weekend’s hot temperatures.”

Hazelfern first experimented with spraying clay during the extreme heat waves in 2021. Since then, the practice has become more common in the Willamette Valley as grape growers adapt to warmer summers, Laing said.

“In late August, the grapes have turned from green to purple and are especially susceptible to sunburn and raisining,” he said.

Bryan Laing. (Courtesy Hazelfern Cellars)

Laing said Hazelfern only applies clay if the forecast calls for 100 degrees or higher. Some growers instead reposition leaves to shade the fruit, and others in warmer regions use shade cloths, though that is less common in the Willamette Valley.

“Winemakers carefully sort the grapes each year as they come into the winery to remove things like leaves and sticks, so if grapes do get some sunburn, winemakers are usually careful to remove those clusters on the sorting table as they can taste bitter,” Laing said. “As a wine region focused on high quality, winemakers in the Willamette Valley do a good job ensuring that sunburned grapes don’t make their way into the fermenters. Ultimately, spraying clay on our grapes is a proactive step that saves us time on the sorting line during harvest.”

More information about Hazelfern Cellars is available at hazelfern.com.