Winter’s Effect on American and Midwest Vines

The Washington Post ran a story yesterday about the damage cold weather has done to Eastern vineyards, particularly in New York and Pennsylvania.  (Cornell University is reporting damage to Riesling and Merlot on Seneca Lake.)  Whatever problems the weather has caused in the Midwest, at least our vines are not budding in mid February, as some Chardonnay is doing now in California.

Midwestern vignerons have mainly taken a “wait and see” position on the coming growing season, except for Ohio and Minnesota, where grape growers have been forthcoming about serious vine and bud damage.

Today,  The Michigan Grape and Wine Industry Council announced that a session about cold damage to grape vines will be added to the Michigan Grape and Wine Conference on February 28th.  Michigan State University viticulture professor Paolo Sabbitini will share data about this winter compared to others and lead a discussion about special vineyard management considerations for 2014.  (Click the Michigan Conference ad on the homepage of Midwest Wine Press for more information about the Michigan Conference in Traverse City later this month.)

Subzero temperatures are unusual in Michigan’s prime grape growing areas near the Traverse Bay of Lake Michigan.  However, this winter the coldest temperature recorded in Traverse City was -6F.  (One would assume that the area’s best vineyard sites are slightly warmer.)

According to Washington State University, -10F is the temperature at which Pinot Noir and Riesling bud mortality exceeds 50%.  Temperatures in the Lake Erie vinifera growing areas of Ohio dropped to -14F during January and Ohio State University reported that the 2014 vinifera crop is close to a total loss.

There are many factors effecting grapevine cold hardiness, including when the cold occurs and the presence of snow cover. And snow is one thing that has been abundant in Northern Michigan this winter.  (Traverse City had over 100 inches of snow by the end of January.) According to research by Rutgers University, it takes only nine inches of snow to insulate the ground from subzero temperatures.

Not as well documented is the effect of protracted cold on plants that are exposed to the air.  This winter has seen a relentless series of polar outbreaks with average and mean temperatures well below historic levels, and certainly below anything that’s been experienced since much of the vinifera wine grapes were planted in the Midwest and Michigan.

However, the Midwest is a huge area, spanning eight USDA Plant Hardiness Zones. And this winter has not been uniform across the region.  While International Falls, Minnesota dropped to -42F this January, some locations in far Southern Illinois and Missouri have had little or no subzero temperatures during 2014.  Therefore, wine grapes in the Southern Midwest will be largely unaffected, including Cab Franc, which is considered moderately cold sensitive by old world grape standards.

In his most recent February newsletter, Hank Johnson of Chaumette Winery, 60 miles south of St. Louis said, “I am delighted to report that Mark Baehmann went out into the vineyard and collected buds from numerous blocks and we experienced almost no bud damage, which tells me that our vines were in good physical condition going into the cold weather. Naturally, this report is a great relief.”

We hope that many more grape growers share Hank’s relief this spring.

See:  Winter’s Effect On American Vines