By Mackenzie Brisbois
Hybrids vs. Vinifera
Not all vines are created equal and some are more winter hardy than others. All the varieties we have planted show some form of damage once temperatures drop down to ice fishing temperatures. Most Vitis vinifera (think Pinot Noir, Chardonnay, Riesling, Cabernet Franc & Gewürztraminer) will start to show damage in the heart of winter when temperatures go below -24°C. The other hybrids we have planted Baco Noir and Geisenheim are slighty more winter hardy, and so they to will show some damage around -30°C. Each year in PEC the temperature drops below -30°C and this temperature is enough to kill some of our plants.
Acclimation and Deacclimation In Grapevines
Acclimation is when the vines get ready for winter. It’s one of my favourite things to talk about because it shows how smart the vines are. Each fall the branches start to turn brown and the vine stores sugar as starch, sending lots to the roots for winter. As temperatures drop, the water moves out of cells, the cells essentially protect themselves by making themselves into an anti-freeze situation.
In the spring the water starts flowing in vines and they come out of dormancy, a process called deacclimation.
Some grapevines, like Gewürztraminer can come out of dormancy easily and they can show damage if we have a lot of +0°C days in the winter. Factors in the season, like drought, over-cropping or other stresses can lower the vines ability to acclimate – meaning it’ll get damaged more easily.
Blankets
The bottom line, is that vines in Prince Edward County need protecting. So every year we blanket our vines with Geotextile fabric. The graph below shows the difference between temperature under the fabric and over the fabric. So when temps in February of 2023 hit -30°C, under the fabric only hit -15°C. That is a temperature our vines are able to survive.