Cold temps create sustainable wine-growing

It is the season of celebration, the time of year we gather together to enjoy the holidays, friendship and family. One of the important focal points of our celebrations include food and wine — two important agricultural products grown in the Yakima Valley.

We think of the Valley’s agricultural bounty during the summer months when we see plants bearing fruit, but rarely look beneath the surface to see what’s happening during the cold winter months.

The winter vineyard reveals the look of sturdy, tranquil vines among the brown hills and sagebrush of the Yakima Valley. Beneath the frost or blanket of snow, the brown, barren twigs are dormant grapevines already preparing for the next vintage. Winter is an important season for Yakima Valley’s vineyards. Cold temperatures create an inherently sustainable wine-growing region, they can also kill vital parts of the plant.

According to Markus Keller, Chateau Ste. Michelle distinguished professor at Washington State University, “Eastern Washington winter temperatures have increased 3-4 degrees in the past 30 years. It’s not uncommon to see bud damage in specific areas, but those deep cold plant killing frosts are more localized and occur less frequently.

“Historically, vineyards in various parts of Eastern Washington would experience a deadly freeze one out of every six years. Today we may see a vine-killing frost once out of every 8-10 years,” says Keller.

The last significant freeze in Eastern Washington was November 2010. Record low temperatures of minus-10 to minus-12 caused significant vine dieback in the Horse Heaven Hills and Walla Walla regions, reducing the crop in 2011. According to Keller, the Yakima Valley and Wahluke Slope grape-growing areas have been less prone to a winter kill than other areas.

Another factor to the region’s lighter winter damage is farming practices. Growers have learned that planting vines deeper and irrigating the plants after harvest are beneficial for winter tolerance.

“Moisture in the soil creates insulation around the plant, reducing the fluctuating temperatures that create damage,” says Keller.

Vineyards planted at higher elevations are also less prone to frost damage. Higher elevation protects the vines from winter because cold air is heavy and settles on lower areas. This is why annual crops are most often planted on the Valley floor.

Cold weather also creates positives for grape growing. Freezing temperatures kill disease-carrying pests creating remarkably pest free vineyards. Phylloxera, an aphid that damages roots in 95 percent of the world’s wine regions is not active in Eastern Washington resulting in little pesticide applications, which lends to more sustainable vineyard practices.

Less pesticides also allow beneficial insects to flourish. The region’s sagebrush is one of the best natural habitats for beneficial bugs.

Although the reason to plant vineyards on hillsides is partly because of frost protection, the quality of the grapes is high because on hillsides you get low vigor soils that drain well. These are qualities that lead to small berries and intense fruit, and high-quality wines.

As you raise your glass this holiday season, consider how both the warm, sunny days and the cool, winter nights of the Yakima Valley impact the wine you are enjoying this winter.

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