Grapes (Vitis spp.) are produced on large deciduous vines with an attractive growth habit. There are hundreds of cultivars of European and North American origin that can be grown in U.S. Department of Agriculture plant hardiness zones 5 through 10, depending on the variety. The vines are easy to care for in most ways, though knowledge of correct pruning techniques will help to enhance productivity and maintain their aesthetic qualities.
A mature grape vine produces dozens of new shoots each year of up to 20 feet in length. Each winter, the vast majority of new growth should be pruned off, while the basic branching structure is preserved for the life of the vine. This approach reduces excessive shading of the fruiting parts of the plant to maximize the amount and quality of fruit. Hand pruners usually are sufficient for the annual pruning of young vines, but loppers or a hand saw will be necessary when pruning the larger vines that form if the plants have been neglected for several years.
The structure that grapes will grow on determines how they initially are pruned and trained. The most simple trellis is a single taut wire stretched between two posts about 12 feet apart. Multiwire variations on this style are just as effective and afford more space for the massive vines. Many home gardeners will want to train grapes over a four-post arbor. With any of these methods, new grape vines should be pruned to have one trunk for each post and as many side branches as there are wires or other horizontal support structures.
Establishing a Fruiting Structure
It is best to prune grapes in late winter while they still are dormant. In the first winter after planting, remove all side branches and cut the main trunk back to just below the trellis wires. After the second growing season, train one vine to each wire and prune off all the others. Use twine or plastic ties to tie the vines loosely to the support structure. The grape vine now will be ready to begin fruiting. For variations with arbors or other trellis systems, simply adapt the methods for training onto horizontal wires to each vertical post and cross piece.
In the third and subsequent years, maintain the original structure of the main branches as a scaffold for the small side shoots that will produce grapes each year. Each winter, prune out any side shoots that are less than the thickness of a pencil and cut the rest back to 8 or 10 inches in length. Prune every other one of these remaining short spurs back another 6 inches, so that there is only one growth bud remaining. The longer spurs will fruit the following year, and the shorter ones will grow and be pruned back as fruiting spurs the year after.
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