Grapes (Vitis spp.) are large deciduous vines with a graceful growth habit and heavy drupes of fruit that ripen in late summer. Depending on the variety, they can be grown in U.S. Department of Agriculture plant hardiness zones 5 through 10. The vines can grow to an enormous size and live for more than 100 years. Annual pruning is necessary to maintain size and stimulate fruit production, but even old, overgrown vines can be brought back to form with some heavy pruning and training.
Cut back the entire grape vine, leaving only the main trunk and two of the largest vines that branch from the main trunk at any point between 2 and 4 feet from the ground. This will not harm the plant, but is necessary to re-establish a good form.
Prune back the two remaining vines that stem from the main trunk to about 6 or 8 feet each. The goal is to have a t-shaped vine that will remain as the basic structure to support the smaller fruiting vines.
Prune off any vines growing from the two main branches that are more than one-half inch in diameter.
Thin out the remaining small diameter vines so you have approximately two or three growing from each linear foot of the main branches.
Cut back every other one of the remaining small vines to 8 or 10 inches and leave the others long. The short spurs can bear fruit the following season, and the longer ones will produce the energy needed by the plant through photosynthesis. .