Bunch thinning or green harvesting is a canopy management operation that consists of removing certain excess bunches on the vine with a view to improving the potential quality of the remaining bunches and/or reducing the yield when debudding has not been sufficient to limit the number of bunches per vine. This is a common catch-up technique. Limiting the yield by removing selected bunches improves the quality of the remaining bunches as it allows the leaves to "feed" fewer wells.
Thinning consists of removing either portions of bunches (e.g. the tip) or whole bunches. Thinning should be carried out at the beginning of véraison, in July, in order to limit the imbalance this procedure causes the vine. It should not be carried out too late, i.e., too long after véraison, since there is less effect on grape quality improvement.