When temperatures hit -18C or lower vines can suffer serious damage

Unexpectedly frigid temperatures last weekend meant the wind machines were running in many vineyards around Niagara-on-the-Lake early Sunday morning.  

The giant fans are used when it gets cold enough to damage the tender buds on the dormant vines.

“It got down to -18, and it was a surprise. That was colder than forecast,” said Matthias Oppenlaender, chair of Grape Growers of Ontario. “We know from experience we  get bud damage at -18 or -19.”

When enough buds are damaged by extreme cold, the vine won’t produce for as long as five years afterward, so avoiding that damage is crucial.

As the temperature dips as low as -18C, the coldest air pools at ground level. The huge fans stir it up, pushing relatively warmer air down to the level of the vines.  

“They have temperature sensors and they’re automated, but the batteries can run down, so we have to monitor them closely,” Oppenlaender explained. 

“This is the first time this winter we’ve needed them. I’m not concerned about the crop, it hasn’t been damaged. But it’s a wake up call. We have to be on alert.”

No one can say how often the giant fans will have to be used this winter, but growers will be keeping an eye on the weather.

 “It’s impossible to predict how the rest of the winter will go, but when we have clear skies it gets cold,” so the big machines will be at the ready to prevent the kind of damage that could ruin next summer's crop.