With a polar vortex approaching, grape growers in Niagara are keeping a close eye on the thermometer. If temperatures dip to a certain low, it could cause serious damage to their vines.

READ MORE: Cold weather alert reissued for Hamilton

Some wineries will go to great lengths to protect their crops. At Fielding Estates Winery in Lincoln, Curtis Fielding is getting ready for a cold weekend.

Fielding says when the mercury dips to around minus 18 or 19, his vines could be damaged, “if it goes below minus 18, 19 we start to see buds getting damaged, so they start burning and it’ll reduce our crop for the next year.”

Fielding says using a system developed by Brock University he can predict how much damage the cold weather will cause.

“They take bud cuttings out in different fields and take them back to a freezer at Brock University… drop the temperature in the freezer, and they can actually tell us at what temperature we’re gonna see the damage,” Fielding said.

If the temperature dips to minus 18 or 19, it could destroy ten per cent of his vines.

“That’s your profit margin for the year. We work with tight margins growing grapes. Any damage is bad damage,” Fielding said.

At Flat Rock Cellars near Jordan Station, their threshold is a little colder. “If it goes to minus 20 we should be fine but anything much lower than that we’ll start to get a little bit anxious.”

Fielding Estates Winery uses wind machines to fight the cold, the wind machines act as a blender, suck the warm air from up above and mix with the cold air and warm the vineyard floor from 5 to 7 degrees.

While Flat Rock Cellars uses their rolling terrain, “we’ll actually be a couple degrees warmer up here compared to what it would be like at the lake and that couple of degrees can make all the difference.”

Other grape growers in the area even hire helicopters to move cold air around to protect their vines.