How2Day: Vineyard Trellis Types

Although grapes grow on woody vines, they lack the structure needed to support themselves. Most grape growers, therefore, employ a trellis to support the vines and foliage. Although many trellis systems exist, the best are those that provide adequate support while also opening the foliage for maximum light penetration, according to the Washington State University Extension. You should also consider the cost of construction, ease of maintenance and compatibility with your harvesting methods, when choosing a trellis system.

The University of Minnesota Extension recommends the four-arm Kniffen systems as the optimal and easiest system for growing winter-hardy grapes at home. Two wires stretch between stakes, one at 36 inches above the ground and the other at 60 inches. As the grape plant grows, the producer ties it to a stake to ensure a straight trunk. When the vine reaches the first wire, begin training the plant to grow along the wire in both directions. When it reaches the second wire, train it similarly, resulting in four vine "arms," and prune back any branches that grow between the wires.

Like the four-arm Kniffen system, the umbrella Kniffen system begins with two wires stretched between two posts. The University of Missouri Extension recommends this system for vigorously growing varieties and praises its ability to allow light and air flow into the leaves, boosting productivity and reducing the chance of disease. Like the four-arm Kniffen system, training begins by tying the growing plant to a stake to ensure an upright trunk, but the trunk is allowed to grow to the top wire before beginning to train the vines. Once it reaches this point, select a vine on each side midway between the two wires, drape them over the top wire and tie them to the bottom wire.

Cordon systems utilize a single wire stretched between two posts, although a second wire is sometimes added for support. Unlike Kniffen systems, where the trunk remains the only permanent part of the plant left above-ground, the cordon system leaves the trunk and one or two permanent vines called cordons stretched along the wire. Single- and double-cordon systems refer to whether one cordon grows in a single direction or two cordons grow in opposite directions. Pruning mature plants involves selecting spurs on each cordon that will produce foliage and fruit the following season. In addition to opening the vines to good light and air penetration, the University of Missouri Extension points out that the cordon system requires little or no tying and offers some frost protection.

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