The vineyard crew is currently preparing for cluster thinning, the sad task of dropping excess fruit on the vineyard floor. This helps to reduce the overall yield of the vineyard, which is critical in vigorous growing seasons like 2015 to maintain quality.
Cluster thinning at Culmina is a precision technique. Jamie has been evaluating the vigour and crop-level of the vineyard, measuring the number and size of clusters. This will allow us to determine the exact amount of fruit to be dropped to meet our target yield. This will vary by grape variety and by vineyard block. As such, it is not simply a matter of leaving 1 or 2 bunches per shoot.
Jaime will then conduct another crop estimation to determine if we in fact dropped the desired amount of fruit. If necessary, we will do a second pass through the vineyard to do additional cluster thinning. This will also help us determine the approximate size of our 2015 harvest.
For example, in 2014, we had to drop nearly 40 percent of our Grüner Veltliner crop to meet our desired level of quality. Grüner Veltliner, though, is a notoriously vigourous variety that ripens unevenly. The 2014 Unicus is currently only available for purchase in our Tasting Room, with limited quantities remaining.
The fruit remaining after cluster thinning will have greater concentration and ripeness at harvest. As a grapevine only has a finite amount of resources, it is important to prevent dilution by not carrying excess clusters. We will also drop clusters that are lagging in their growth – whose skins have not yet changed colour after veraison – as they are unlikely to reach physiological ripeness.
Managing yields through cluster thinning is just another means of ensuring we produce wines of excellence.