Too cold for icewine: Overnight temperatures could damage Okanagan grape vines

Okanagan’s grape growers will be watching temperatures closely tonight as forecast lows are expected below -20 Celsius.

Temperatures below -22 Celsius can start to have damaging effects on some varietals, and this week’s cold spell is bringing those kind of temperatures to parts of the Okanagan.

Summerland’s Pacific Agri-Food Research Centre Viticulture biologist Carl Bogdanoff says there’s not much growers can do to protect vines from excessive cold, although wind machines can help.

“These are very good at keeping the cold air from pooling under calm conditions, which can make low spots and valley bottoms even colder,” he says.

Vineyard owners who have just started to prune, or who are in the midst of pruning, might consider pruning less heavily if temperatures drop to -22 C or lower.

Bogdanoff says an advantage to pruning late in the season is the grower can then adjust pruning levels in response to possible cold weather bud damage.

Environment Canada meteorologist Doug Lundquist says this week's low temperatures in the Okanagan haven't dropped as low as predicted in some areas, which will be good news for growers, largely due to the warm temperature of Okanagan Lake for this time of year.

On the icewine front, Wine Growers British Columbia communications director Laura Kittmer says before the start of this week's cold snap, three wineries had picked about 12 tonnes of icewine grapes in Summerland, Keremeos and West Kelowna, out of 300 tonnes registered with the B.C. Wine Authority.

This week, picking continued on the Naramata Bench, Penticton, Okanagan Falls, Oliver and other areas, but now the weather is a case of too much of a good thing.

She says picking is taking place throughout the Okanagan Valley now and ass of yesterday afternoon, Feb.10, another 43 tonnes has been picked this week.

But Kittmer says icewine production has slowed down the last couple of days, now because it is too cold.

“The grapes have frozen so solid, they can't be pressed. There was a window there earlier in the week where the wineries picked, but now it's too cold. It's a finicky thing, but that's why they call it liquid gold,' she says.

Growers might have another window of opportunity later this week as the cold front begins moderating on the weekend. Nonetheless, Kittmer believes this will be a low production vintage year for icewine production.

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