(Wines&Vines) - Earlier this month in Minneapolis, grapegrowers, winemakers, nursery owners and others spent three days engaged in what one of them called “a lot of blunt and ego-free talks” as part of the 39th annual Cold Climate Grape Conference. Here, they shared anecdotes, studies and hard-earned wisdom about growing and vinifying grapes in not-so-hospitable conditions.

The primary topics were the effects of last winter’s “polar vortex,” how to market cold-climate varieties and which grapes do well for them and why. Participants also learned about sweet wines, acidity and water additions. 

The takeaway? “The cold-hardy ramp-up continues,” said conference director Steve Unverzagt.

The conference’s first day was tweaked to home in on three topics: distilling, how to start a vineyard and a sommelier course. “That generated a lot of specific and deep-dive attendees and was very successful,” Unverzagt said.

During a talk on the polar vortex, University of Minnesota viticulturist Peter Hemstad displayed the dictionary definition of the vortex as “a persistent, large-scale, upper-level cyclone near one of the Earth’s poles,” which last year dropped down well into the United States.

“We all suffered a lot, as did our grapevines,” added Hemstad, who also serves as co-owner/winemaker at Saint Croix Vineyards in Stillwater, Minn. His state had 53 days below zero last winter, and in such conditions, “Vines can’t support the buds and they collapse. The vine already knows it’s a lost cause, and so it puts its energy into shooters.”

The foremost victims are the primary buds. A study cited by Hemstad showed that only two red grapes—the Russian variety Baltica and the table grape Valiant—had primary-bud survival rates above 32%. Frontenac had a primary bud survival rate of 27.1%, with Marquette at 14.6%, Maréchal Foch 10.4% and Norton zero chance of survival in the states and provinces surveyed. On the white grape side, Frontenac Blanc (45.8%) and La Crescent (39.6%) did best, with St. Pepin at 22.9% and Edelweiss at 18.8%. For comparison’s sake, the mean primary-bud survival from 2009 to 2013 was 95.7% for Marquette and 90% for Frontenac.