Prune grape vines with pruning shears, taking off significant amounts of new growth during the dormant period of late winter. To prune a heavily overgrown grapevine, cut as much as 90 percent of the plant's total growth down to the major trunk to encourage new growth.
The most common mistake when pruning grape vines is not pruning enough growth. Grapevines are generally hardy plants that grow well across most of the United States, and are fairly forgiving of too much pruning rather than too little, as they grow quickly again the following year.
Most grapevines come from garden centers with two to three shoots already growing. Let up to four shoots grow and then select the best two to train up your supports to the fruiting area. Trimming all the unwanted shoots encourages the main ones to grow. Use twine to secure the best shoot to the supports if necessary. Continue training one to three shoots up to the fruiting wire or roof of your arbor each year.
Once established, cut back most woody growth in the fruiting area every year, but keep the woody trunks leading up to the fruiting area. This allows new growth to cover the fruiting area each year, which helps produce more grapes. Some varieties of grapevine require winter protection in some climates. Prune these varieties back to an easily removable woody trunk.