Many backyard grape growers overlook the necessity of pruning their grape vines, but unless your vines are properly pruned you run the risk of the grapes setting too much fruit for the vine to properly ripen, and you may weaken the vines and shorten their lives. Fortunately, pruning grape vines is not rocket science. Prune only in late spring or early winter, to increase the following season's harvest. The following instructions apply to pruning any grape vines you may have.
Remove all old growth (older than one year) from your mature grapevines. Grapes will form next season only on last years healthiest growth.
Select the four healthiest (thickest) new canes, which grew during the last summer. Cut each of these canes, leaving approximately 15 buds on each cane. If you are growing table grapes then leave 50 to 80 buds in total per plant.
Identify all cane spurs. These are small branches growing off the main canes which you selected to save. Trim these small spurs, leaving just one or two buds per spur.
Remove all other canes and spurs.