#PolarVortex is trending on social media while people across the Midwest are hibernating at home with work and school canceled. The US Postal Service has suspended operations from Michigan to Eastern Nebraska due to windchill extremes. Amtrak trains have even stopped running in some areas.

Has it made you stop to wonder: if a train cant run, how can anything else survive?

22 states will experience brutally cold wind chills over the next few days. Aren’t you glad you’re not in #minnesota ? @FOX29philly pic.twitter.com/9xDTwP2I4z

— Kathy Orr (@KathyOrrFOX29) January 30, 2019

Worrisome Winter

For the majority of the world’s winegrowing regions, winter is a peaceful time of renewal in the vineyard.

Fall harvest initiates a grapevine’s winter wind-down ritual, with a switch of vine energy from producing and ripening grapes, to developing and deepening roots to nourish itself.

Here in Minnesota, winter is a tense time of pondering why the heck we even live here, and when is it ever going to end?

Grapevines that survive in the upper Midwest are referred to as “cold hardy” or “cold climate” varieties. But how hardy are they, really? Many European and International grape varieties, Riesling and Chardonnay for example, can survive temperatures as low as -15 or -20 F.

Three of Minnesota’s most popular cold-climate hybrid varieties, Marquette, Frontenac Gris, and LaCrescent, have been studied to survive temperatures as low as -35 F. Survival does not imply free from injury though, and the longer the duration at which extreme temperatures last does seem to pose a greater threat.

The risk of cold weather to grapevines is damage is to the spurs or canes (necessary for the development of fruit), the cordons (larger limbs of the vine that hold the spurs/canes) or the trunk of the vine itself. The severity of damage can range from diminished to non-existent fruit production the coming season, or death of the vine itself.

A Snowy Safeguard

In the early 1970’s as many of the cold-hardy hybrid grape varieties were first being developed, each grapevine needed to be laid down on the ground bedded down with an insulating layer of hay in order to survive the winter. Imagine having to bury by hand, each of the 5,000 vines in an average Minnesota vineyard before each winter? I’d rather not.

Fortunately, there are a number of grape varieties, many developed by our own University of Minnesota, that have mostly eliminated the need for bedding the vines each winter, one exception being very young vines which are sometimes protected for their first year.

Just in the nick of time, we received a blanket of snow across much of the state in the days preceding the cold sweep, which will help insulate trunks and roots over these next few days.

Jack Frost’s Retreat

Over the coming months, Minnesota’s vintners will get out their heavy insulated winter clothes, sharpen their pruning tools and trudge out to the snow covered vineyards. The only way to prune a grapevine is by hand.

They will first test for winter injury by taking samples from the vineyard to determine the amount of loss, and and then begin planning their pruning strategy and for production — or loss of production — for the coming growing season.

Pruning a large vineyard through the chill of winter can quickly remove the idea of owning a vineyard as a romantic lifestyle.

– Dave Mohn, Flower Valley Vineyard

While grapevines are amazingly resilient, perhaps it is Minnesota’s grape growers that are even more so?

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A post shared by Schram Winery & Brewery (@schramvineyards) on Jan 29, 2019 at 9:19am PST