How do I winterize my grape vines.

what is your location

check with https://ask.extension.org -- they will respond for your grow zone and the variety of grapes

Canadians don't and they get pretty cold.

Barbara is right.

If the temp dips below freezing, and there is still fruit on the vines, then the crop will be lost. However, if the plant has finished fruiting for the season, and the leaves have dried up and fallen off, then the plant is in its dormant season.

Dormant- from the French word dormer- meaning sleep. Dormant season for a plant is like hibernation for animals. This is natural winterization.

I planted some grape vines in Anchorage AK, zone 3-4, that did not survive. I was part of a pioneer fruit growers organization who brought someone up who was selling vines that were supposed to be hardy. They were not. None of the vines survived other than a few a man put in his heated green house. These vines were expensive and mailed to us at the 'right' time. I was disappointed.

Well we are not Alaska but Maine where we only have a few sub zero days each winter, but we do have very cold days. Our grape vine is doing fine after 30+ years.

Grapes do not grow in All areas of Canada. I am referring only to areas in Canada where grapes Do grow- Niagra area in Ontario, Okanagon in British Columbia, and Vancouver Island in British Columbia. Although these zones are the warmest in Canada, the winter temperature does drop below the freezing point.

Only select strains of grapes will grow in these geographical areas, not all kinds of grapes. I have never of any kinds of grapes growing as far north as Alaska.