"We don't really know exactly how the wines are doing," said Paul DeCampo, sales and marketing director at Southbrook Winery in Niagara. "There's certainly some indications that it's going to be problematic. We're still hoping for the best and preparing for the worst."
What that worst-case scenario looks like will depend on the region and the variety of grape. Could the growers be looking at half of their crops impacted?
"It could well be worse than that," DeCampo said.
After a historically large crop in 2013, growers hoped the cold winter in 2014 would be the end of it.
"We were hoping for a recovery," DeCampo added. "That was the goal. We were hoping, 'Oh, there's a one year glitch we'll roll with that and go forward.'"
Rick VanSickle wrote about the tough winter on his website "Wines in Niagara."
"The latest results are particularly tough to swallow coming in the wake of 2014 that was the worst winter since 2005 and caused wide-spread damage to the most vulnerable grapes in Ontario, especially Syrah, Merlot, Sauvignon Blanc and Semillon," he wrote.
'A nice blanket of snow'
But there are some encouraging factors. A "nice blanket of snow" may have insulated some of the vines from damage. "We won't really know the size of the crop at all until late spring, early summer," said Debbie Zimmerman, CEO of the Grape Growers of Ontario.
Jim Willwerth, a scientist in the Cool Climate Ooenology and Viticulture Institute at Brock University, said growers this year have been advancing their use of cold-winter technologies like strategic pruning (leaving more buds on the vines before a cold snap) and wind machines that circulate warmer air to the bottoms of their vine trunks.
Willwerth said that "spare parts viticulture" and the growing use of wind machines had an effect last year.
"That's why we weren't as bad as we could've been last year," he said.
But some vines may have been back on their heels from 2013-2014's winter when another cold spell hit.
"The other unknown is back-to-back winters," Willwerth said. "If a vine is not healthy from last year it might not do well this year."
Willwerth's team publishes "Vine Alert" which compiles statistics from growers who survey their vines and estimate how much damage there's been. Some of the readings look pretty bleak. A reading taken on Feb. 23 indicated a 19 per cent bud survival for Cabernet Sauvignon in Creek Shores.
But by March 3, things were looking a bit better. The Cab grapes in Creek Shores had a 43 per cent survival reading.
The real survival rate for this year's crop is probably somewhere in between, said Willwerth. Different varieties, regions and wineries will have been impacted differently.
"We are still sampling and getting better assessments," he said. "Our assessments improve as we collect more data and get closer to spring, too. It's a biological system and there is inherent variability."
Zimmerman said growers in this region tend to be resilient. Some can "retrain the grapevine" and coax a living branch out of it.
All of the research has been going right into the region's attempts to grow wine. Still, Willwerth said he wouldn't wish a cold winter on the industry in real life. He'd rather test his theories in his laboratory freezer.
"I'd rather have it as an experiment," he said.