Why is it necessary to prune grapevines?

Question:

Why is it necessary to prune grapevines?

Answer:

Grapevines produce fruit clusters on the previous season’s growth.  Before pruning, a grapevine may have 200 to 300 buds capable of producing fruit.  If the vine is not pruned, the number of grape clusters would be excessive and the grapevine would be unable to ripen the large crop or produce adequate vegetative growth. 

The purpose of pruning is to obtain maximum yields of high quality grapes and to allow adequate vegetative growth for the following season. 

Learn more in this article: How to Prune Grapevines in the Home Garden.