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 will not be able to run exotherm analysis in grapes any more. 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.
- 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 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.
Preventing Cold Damage in Grapes:
Assessing Cold Damage in Grapes:
Responding to Cold Damage in Grapes:
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).
More information on modeled cold hardiness can be found at our Cold Hardiness Modeling page: http://wine.wsu.edu/extension/weather/cold-hardiness/model/