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Grapevine Cold Hardiness

On this webpage you will find the following information:

  • Real-Time Monitoring – This is a table of actual measured cold hardiness for specific varieties grown at WSU Prosser IAREC. Updated weekly to bi-weekly.
  • Variety Graphs – A variety-specific seasonal overview of cold hardiness over time.
  • Seasonal Summary – A general overview of temperatures and precipitation, along with cold hardiness, for Cabernet Sauvignon and Chardonnay.
  • Initial Fall Cold Hardiness, Potential Maximum Cold Hardiness in mid-Winter, and Spring Frost tolerance of select varieties. This is data summarized from our historical monitoring.

Real-Time Monitoring

 

Warning: Please evaluate buds before you prune to decide on compensatory pruning strategies!

 

Even though our data posted on this website and the cold hardiness model on AgWeatherNet indicate temperatures reached in mid-January (-4°F in Prosser, 3.2°F in Walla Walla, 2.8°F in Columbia Gorge on January 15) were not low enough to kill buds instantly, the temperatures stayed low enough long enough to cause bud dehydration to the point that some buds would have died. In this scenario, the water within the bud cells does not freeze (it would freeze at the temperatures indicated in the table and graphs below), but the extracellular ice that forms pulls water out of the cells so long as it remains frozen. This process dehydrates the bud cells (i.e., the shoot and cluster primordia), and the growing ice mass may eventually even crush the cells in the interior.

In the Roza vineyard at WSU Prosser we found the following bud injury levels following the January 2024 cold event:
Note: The damage in your vineyard may differ from the numbers listed in the table above. Bud injury is highly variable depending on the location, variety, and vigor level. Differences in elevation and aspect can mean the difference between insignificant and substantial damage. Also, the same variety may have little damage at low to moderate vigor levels but substantial damage at high vigor levels. Please consult the information links provided on the right about how to assess cold damage and how to apply compensatory pruning where needed.

Critical temperatures

Variety Graphs

BUD10 is the temperature at which 10% of the primary buds will be killed; BUD50 and BUD90 refer to 50% and 90% bud damage, respectively. PHL10 is the temperature at which 10% of the phloem (bark) is damaged or when cane damage is starting. XYL10 is when phloem damage is complete and xylem (wood) 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.

Select a variety name below to see the current season observed cold hardiness.

 

 

 

 

 

 

 

In the Spring

When we are at or approaching bud break, we can no longer run exotherm analysis in grapes.  Below are some general guidelines as to the critical temperatures for cold damage for Cabernet Sauvignon, Merlot, and Chardonnay during the period leading up to bud break. Every variety responds differently to cold temperatures, so these are for guidelines only.

  • Cabernet Sauvignon at budswell sustained no damage down to 25°F.
  • Merlot at budswell 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 budswell to budbreak 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.

Resources

Preventing Cold Damage in Grapes:

Assessing Cold Damage in Grapes:

Responding to Cold Damage in Grapes:

Modeling

Washington State University has developed a Cold Hardiness Model to predict grapevine cold hardiness anywhere temperature data is available. It is available both as an EXCEL sheet (to enter your own weather data), or via AgWeatherNet (for WA locations).

For the EXCEL version: Send your name, affiliation (Government, University, Grower, Consultant, Student), and location (City, State/Province, Country), in an email to: wsu.vitcoldhardiness@gmail.com

Please use “Cold Hardiness Model Request” as the subject line. You will receive an automate reply which will contain a link to download the file. We are asking for your contact information so that we may track where the model is being used.

 

Seasonal Summary

Seasonal summary graphs will be updated starting in November 2023

Initial Cold Hardiness, Maximum Cold Hardiness, and Spring Frost Tolerance

 

The below table shows initial fall cold hardiness (mid-September) and potential maximum mid-winter cold hardiness for grapevine buds. It also shows frost tolerance of green tissue in the spring following budbreak.

Information is modified from Table 4 in Ferguson et al., 2014 (AJEV).

Variety

Initial Fall Cold Hardiness

(°F)

Potential Maximum Mid-Winter Cold Hardiness

(°F)

Frost Cold Tolerance- Post Budbreak

(°F)
Barbera 13.8 -10.3 29.8
Cabernet franc 14.2 -13.7 29.8
Cabernet Sauvignon 13.5 -13.2 29.8
Chardonnay 10.8 -14.3 29.8
Chenin blanc 10.2 -11.4 29.8
Concord 9.0 -21.1 27.5
Dolcetto 13.8 -9.8 29.8
Gewurztraminer 11.1 -12.8 29.8
Grenache 14.0 -8.9 29.8
Lemberger 8.6 -14.1 29.8
Malbec 11.3 -13.2 29.8
Merlot 13.5 -13.0 29.8
Mourvedre 14.9 -7.8 29.8
Nebbiolo 12.0 -11.9 29.8
Pinot gris 10.4 -11.4 29.8
Riesling 9.3 -15.0 29.8
Sangiovese 12.7 -7.4 29.8
Sauvignon blanc 12.9 -12.8 29.8
Semillon 13.3 -8.3 29.8
Sunbelt 10.8 -20.4 27.5
Syrah 13.5 -11.6 29.8
Viognier 11.8 -11.2 29.8
Zinfandel 13.3 -11.9 29.8