Temperatures in the Ottawa region fell to 28F (-2C) at about 3am local time early on Tuesday morning.
Phil Lyall of Mountain Apple Orchards, about 37 miles south of Ottawa, told public broadcaster CBC he paid thousands of dollars to have a helicopter fly all night over his 10,000 trees in order to push rising warm air back down and keep temperatures on the ground above freezing.
It was the second time in two years that he tried it, after hearing that fruit growers in Argentina, New Zealand and elsewhere were doing the same in similar circumstances when their crops were threatened by cold.
Last year, he recorded a 10-point jump in temperatures in his 25-acre orchard, from 26F (-3C) to 37F (3C).
He said his orchard might lose only 10 per cent of its apples when temperatures drop to 32F (0C), but a night below zero can kill 90 per cent of his crop.
"The MacIntosh (apples) are just about in full bloom, some of them already are, and that puts them at their most susceptible stage right now," he said.
