January 4, 2018 - Cool Climate Oenology and Viticulture Institute's VineAlert

The following is an alert regarding grapevine cold hardiness and the low temperatures in regions across Ontario.  We are experiencing colder temperatures as a result of a "polar vortex" which has pushed a large system of very cold air into our region.  Some of the coldest temperatures are predicted to arrive over the next few days.  Current forecasts indicate that temperatures may drop below -20 C in some areas between Thursday and Saturday.   Wind will also be associated with these colder temperatures so there may not be inversions or ability to run wind machines due to risk of damage to the machines.  However, it is important to be prepared in case temperature mitigation opportunities exist.

We have initial bud survival data posted and are currently assessing bud damage and will continue these efforts following this cold weather.

From our latest cold hardiness testing, the most sensitive cultivars (Merlot, Sauvignon blanc, Syrah) may sustain some freeze damage when temperatures drop below -19 C. THE LATEST COLD HARDINESS DATA can be viewed at    

It is possible that temperatures could fall below critical temperatures under the right conditions and it is important to monitor vineyard temperatures and be prepared to use protective measures if possible. 

Start-up temperatures for wind machines should be adjusted to account for what we are currently seeing with vine cold hardiness.  For optimal use of wind machines, it is suggested that the start-up temperatures be set at 2 to 3 degrees warmer than temperatures at which injury might occur. Wind speeds should be monitored along with temperatures due to the characteristics this cold event.

Please note:  Cold hardiness ratings are estimates only and the information provided is for general guidance.  Cold hardiness ratings are site specific and may vary based on vine health, viticulture practices and site condition, among other factors.  Any decisions for protection strategies should be based on your own information and site conditions.