This information is provided as a service by WSU with partial funding from the Washington Association of Wine Grape Growers through the Washington Wine Industry Foundation and the Washington State Concord Grape Research Council.  Conditions in your area may vary depending on your specific environmental conditions and viticultural practices. WSU is not responsible for any damage from the use or misuse of this information.

Critical temperatures for wine and juice grapes are determined using differential thermal analysis as described by Mills et al. (1) and are updated weekly from mid October through mid April.  The following information was taken from buds and canes (node positions 4-7) of mature vines grown at the WSU Irrigated Agriculture Research and Extension Center 5 miles north of Prosser and nearby commercial vineyards.  

Clicking on a variety name will open a new page with the seasonal cold hardiness graph specific to the chosen variety.

Final Update: April 18, 2008 3:04 PM

Now that we are beginning to observe the range of development between first swell to full swell in the different varieties, the following guideline might be helpful. 
As we approach bud break, we won’t be able to run exotherm analysis in grapes much longer.  In previous years we have included the critical temperatures for several different varieties during the period leading up to bud break.  Since every variety responds differently to cold, this should be used only as a rough guideline.  In April of 1997 we ran some freezing tests on grape buds and canes at different phenological stages and found the following:

• Cabernet Sauvignon at first swell sustained no damage down to 25 F.
• Merlot at full swell showed slight damage to the buds, phloem, and xylem at 25 F.  More serious damage to the phloem and xylem occurred at 23 F. 
• Chardonnay at bud break showed slight damage to the buds and phloem at 27 F. More serious phloem and xylem damage occurred at 25 F.  Buds were seriously affected at 24 F.
•  Interlaken at first leaf stage sustained cane damage at 28 F and leaf damage at 26 F. Both cane and leaf damage became serious at 25.

BUD10 is the temperature (degrees Fahrenheit) at which 10% of the primary buds will be killed.  Likewise BUD50 and BUD90 refer to 50% and 90% bud damage respectively. PHL10 refers to the temperature at which 10% of the phloem is damaged or when cane damage is starting.  XYL10 is when phloem damage is complete and xylem damage is starting.  This would be considered severe cane damage. Grapevines can survive more than 50% phloem damage and still be productive.  When xylem becomes damaged, grapevine productivity and survival can be compromised.

Cold hardiness values will vary in vineyards depending on preceding local environmental conditions.  Temperatures during the 2-3 days prior to assessment of cold hardiness are particularly important.  In general, if the temperatures in your vineyard have been colder than those at WSU-Prosser your grapevines would be hardier than the stated temperatures. Likewise, if the temperatures in your vineyard have been warmer than those at WSU-Prosser your grapevines would probably be less hardy. PAWS (Washington Public Agricultural Weather System) can be used to monitor temperatures at weather stations at over 56 locations in Washington.  For more detailed information, the 2000 ASEV Cold Hardiness Workshop Proceedings (2) is an excellent resource on grape cold hardiness.

 

1. Mills, L., J. Ferguson, and M. Keller.  2006.  Cold-hardiness evaluation of grapevine buds and cane tissues.  Am. J. Enol. Vitic. 57:194-200.

2. Cold Hardiness Workshop.  2000.  Proceedings of the ASEV 50th Anniversary Annual Meeting.  Seattle, Washington.  pp 35-114.

   
   



Related Grapevine Cold Hardiness Links:

 

• Cold Damage in Grapes Washington State University

• Anatomy of Grapevine Winter Injury and Recovery Cornell University (requires Adobe Acrobat)

• Assessing and Responding to Winter Cold Injury to Grapevine Buds Cornell University

• Dealing with Winter Cold Injury to Grapevine Canes and Trunks Cornell University