In some instances the vines may set too large a crop for the vine. If left with too large a crop the vine will not properly ripen its fruit. The resultant wine can be too light in color and flavor, thin, or it can be coarse and harsh in flavor. The winegrower knows with experience the capacity of a vineyard, and when he or she sees that capacity exceeded, they will thin the clusters early in the summer to reduce the crop size to appropriate levels.
Where the vine becomes too vegetative and grows a thick, dense, leaf canopy the shoots and clusters may not get enough light. Filtered light is necessary for bud fertility and grape quality. It may be necessary in a vegetative vine to remove leaves to open up the vine to sunlight. This is not as great a problem on Spring Mountain's stressful hillside locations, as it is for other growers in rich, moist valley floor vineyards. There are a couple of blocks on La Perla that have dense leaf canopies and northern exposures. These may be leaf thinned.