Not exactly good weather for grapevines, eh?
Well, it could be worse.
"A lot of what we grow can handle 20-below," said Kyle Peterson, who shares winemaking duties with his dad Kevin at WineHaven in Chisago City, "but you get colder than that and you might see some winter kill."
Peterson said the grapes recently developed by the University of Minnesota (Frontenac, Fontenac Gris, Marquette and La Crescent) "are supposed to go to 30-below."
U of M Enology Project manager Katie Cook said via e-mail that those vines should be hardy at least to 25-below, and that La Crescent has survived at 30-below, "but that doesn't mean that they don't suffer from the cold."
The timing of the seriously low temperatures plays a part in how much damage might occur, she said. And even if the vine's buds emerge in the spring, there can be trunk damage that might restrict sap flow, Cook added.
For his part, Peterson is more concerned about hybrids developed for New England and eastern Canada, such as Marechal Foch ("that's going to be right on the edge"), and even those from Upper Midwest grape pioneer Elmer Swenson such as St. Croix.
As bad as the conditions are now, Peterson is grateful to have more than a foot of snow in his vineyards. "I'd rather have it like this. Some of these roots are shallow and can die when there's not much of a snow pack. We lost several rows of St. Croix like that.
"But I grew up in agriculture, so I know you take what you get. And that with something like this, there's nothing you can do about it."
It's early yet
Jim Luby, who has directed the university' fruit-crop breeding program for three decades, said that a single cold snap is the tip of the iceberg when to comes to damage. Even though some Minnesota grapes survived minus-30 readings in the 1990s, and the vines are at their most dormant and hardy in January, he anticipates some harm from accumulated stress.
"Some growers may already have some damage from cold in December after a mild November," Luby said, "[and] this is only the first week of January. Even if vines make it through this week, we have a lot of winter yet to come.
Still, Luby said that growers who have taken good care of their vines have a better chance of avoiding problems. "Local grapevines that were not overcropped, that were healthy going into 2013, were well watered during our 2013 drought, and received timely disease control have a good chance of surviving minus-25 to minus-30."
Luby's compatriot, University of Minnesota research viticulturist Peter Hemstad, agreed that well-managed vines will prove more cold-hardy. Still, he fears that some farmers, "lulled by the recent mild winters," might have planted vines in places where bitter-cold weather can slam them.
Hemstad also pointed out a potential bright spot, at least for the U of M.
"I think what's going to happen next is we'll get a lot of phone calls from people east of here and south of here, where it's been much colder than usual," he said. "This might increase the level of interest in our cold-hardy grapes."
As for those north of here, Tami Bredeson, co-owner of Carlos Creek winery in Alexandria, is "praying that global warming comes back."