Hey Good People! Pruning grapevines during their deep dormancy—typically between December and February—is vital because it ensures the plant has successfully moved its energy reserves (carbohydrates and minerals) from the leaves into the trunk and roots for winter storage. If you prune too early in the autumn, you "starve" the vine of these essential nutrients, leading to poor bud development and weakened growth in the spring. The window is relatively small and specifically timed for two reasons