Jim Willerth collects samples of grape vines for CCOVI's VineAlert program.

With extreme cold weather alerts across most of the province, Ontario vineyards are also feeling the chill. With next year’s grape crop at risk from the frigid temperatures, researchers at Brock University have issued a grapevine cold hardiness alert for growers across the province.

VineAlert, a program operated by Brock’s Cool Climate Oenology and Viticulture Institute (CCOVI), tracks a grape bud’s ability to survive cold temperatures over the dormant season from October to April. The alert system indicates at what temperature different varieties would see damage when cold weather events occur. This helps growers know when wind machines or other freeze avoidance methods are warranted to protect buds and vines from winter injury.

“In some regions, potentially damaging temperatures are in the forecast,” says CCOVI viticulturist Jim Willwerth. “From our latest cold hardiness testing, the most sensitive cultivars (Merlot, Sauvignon blanc and Syrah) may sustain some freeze damage when temperatures drop below -19C.”

When cold hardiness monitoring shows a potential damaging event like the temperatures experienced this week, Willwerth and Kevin Ker, a CCOVI professional affiliate, alert growers to the danger through VineAlert’s notification system first. Then after the cold event, they head to the vineyard to test grapevine bud survival.

“This bud survival knowledge is extremely valuable to grape growers,” Willwerth says. “If growers have not been able to prevent damage to the vines, winter injury can also be mitigated through pruning practices and adjustments in the vineyard that will allow for more consistent crops and reduce economic loss.”

VineAlert collects samples and monitors hardiness at 13 sites across the Niagara Peninsula, Lake Erie North Shore and Prince Edward County. Growers can specify their location and receive alerts when temperatures in their area approach the lowest temperatures grape buds can survive.

View the most recent cold hardiness data visit

View VineAlert’s cold hardiness alert for growers