Seasonal update 2022: GDD, veraison is done, grape sampling and starting harvest!

Wednesday, September 14, 2022

Jeff Franklin from AAFC Kentville is sharing with us weather information with positive values of growing degree values like last week. Veraison is almost done in the latest Vitis vinifera varieties, such as Pinot noir and Riesling. Even though these last varieties are reaching this phenological stage, in some cases hybrids are starting to be harvested for specific wine styles. Just remember, it’s always important to reach the wineries to know which are the grape ripening requirements and when would be the best time to harvest the grapes.

The first table shows the temperature base 5⁰ C and 10⁰ C from 2019 until 2022 accumulated from March 1 until September 13. At the end of each section, it’s possible to see the average of the last 5 and 10 years respectively.






5 year average

10 year average

Plant development (Base 5ºC)







Insect development (Base 10º)







Figure 1. Degree day accumulations as of September 13, 2022.  All data are taken from the Kentville weather station, based on a start date of March 1, and calculated using the single sine method.

Like last week, we can see 2022 with values higher than 2021. Compared to the 5- and 10-year average, 2022 maintains a considerable higher accumulation of degrees. Mentioned last week, this increase of temperatures combined with the dryer conditions have impacted positively in the fruit ripening and depending on the location even accelerating the process. Therefore, look at your records as harvest, as it looks quite similar to, even slightly higher, than the previous seasons.

In the following column graph, you can see the values from 2005 until 2022 and at the end the average of the last 5 and 10 years respectively.

Figure 2. Degree day accumulations as of September 13, 2022 base 10⁰ C. All data are taken from the Kentville weather station, based on a start date of March 1, and calculated using the single sine method.

Already mentioned in the previous table, 2022 the accumulation is higher than previous seasons and it is higher than the 5- and 10-year average. Compared to previous seasons, 2021, 2020 and 2018 are very similar than the current season and only overpassed by the season 2012. Look at your records of how the previous seasons were to be prepared for harvest and have an active communication with the wineries on how they plan to proceed.

Veraison started in the middle of August with the earliest hybrids turning color, such as Baco noir and Castel, and now even the latest Vitis vinifera varieties, such Riesling are finalizing this stage. The combination of warm temperatures and less precipitation have impacted the grapevines accelerating the ripening process. Depending on the winery goals, it might be necessary to harvest earlier or later in the season. To know when the most convenient harvest date is, it’s important to reach the winery and establish an active communication plan to coordinate the harvest. The winery might request information to be able to take the best decision depending on the wine expected to be produced.

Figure 3. On the left Castel and on the right Seyval.

Figure 4. On the left Chardonnay and on the right Pinot noir.

Related to the communication with the wineries and already mentioned last week, it’s important to track grape ripening to help taking harvest decisions and inform to the winery on how the maturity is moving along in your vineyard. Remember, the results will be as good as the sampling performance. The sampled grapes need to be representative of the plot that they are coming from. It’s a good idea to collect a minimum of 100 berries from a specific variety and repeat in the same area(s) to be able to track the ripening process. Finally, Alab from Acadia University provides analytical services for grape ripening, please take a look at the lab webpage for more information