It is in this delicate phase when the fecundation occurs. The cluster “cleans” the flower, and the grains or “unripe grapes” as we call them here, start to form. It is then when we start to see what the grapes will be like. They increase in size as the season advances, and will take their place in the cluster, ripening until harvest time.
The setting rate of the clusters depends on a lot of factors, but mainly on weather conditions. For the grape setting to be good, the weather must remain stable throughout the flowering period – not too much rain or moisture as this would have a negative impact on the process. Although we do not want the setting to be excessive, as the clusters would be too laden and compact, and ripening would become quite complicated. As always in life, virtue is the happy medium.
At the Sonsierra vineyards, we have seen that this year’s plant cycle is a week behind last year’s cycle. The setting rate is very positive, around 80%, which means that there are fewer grains and these are not so compact, which will help the cluster to ripen better.
Due to the April frost that affected some isolated shoots, we have seen a curious phenomenon. Stocks with clusters still in flower and clusters with pea-sized grains. Whims of nature and the climate.
We will soon be witnesses of one of our favourite times in the vineyard, the veraison.