To keep your vines producing quality fruit year after year, you need to train and prune them regularly. New growth during the summer replaces old, worn out vine. Prune grape vines during the dormant season for quality fruit development the following year. The second year growth produces the grapes and must be cut back to keep the grape vines from producing so much fruit that the grapes do not ripen.
Remove the fruit and foliage before pruning the grape vines. Clear away any debris and old, spent vines to expose the main trunk. Cut off any unwanted shoots coming from the main trunk.
Mark first, second and third year growth each with a different color of marking tape or cloth strips. Keeping the growth color coded makes pruning easier.
Prune back the third year growth and remove the trimmings. Always keep the area clear as you prune the grape vines to allow a good visual of what still needs to be cut back.
Wire the second year cordons to the trellis or growing system, to keep them trained. The cordons are the canes which will produce the vines for the following season's fruit production. Cut the ends of the cordons, leaving seven or eight vines hanging down. A pruned two-cordon system leaves 14 or 16 vines on either side of the main trunk.
Trim back the canes attached to the cordons so there are at least 30 to 40 buds per cane. Remove any other grape vine canes not needed. Inspect the wire fasteners and replace or repair those that appear broken.