This article breaks down the topic by focusing on the easiest method for training American table grapes, which are the most commonly grown grapes in home gardens, as well as the basics of grape pruning.
Grapevine Terminology
First, here are the key terms used in grape training and pruning, namely the different parts of the grapevine:
Trunk: The permanent, upright stem of the grapevine.Shoots: The new soft, green and succulent growth on one-year old wood, with leaves, tendrils, and flowers clusters that develop into grapes.Canes: Mature, woody, brown parts of the grapevine. Canes are either mature shoots after they have produced fruit and the leaves have dropped in the fall, or canes that are able to bear fruit; those are called fruiting canes.Cordons: Used in grape training and pruning when referring to the “arms” of a grapevine that extend from the trunk. They are often positioned horizontally along a trellis wire.Spurs: One-year-old short and stubby canes that have been pruned so that only two to four buds remain. Spurs will grow into shoots, and later, after bearing fruit, into canes.Renewal Spurs: Spurs that are cut back to only one node—the location on a cane where the buds emerge. The purpose of having renewal spurs on a grapevine is to grow shoots for next year’s fruiting canes.Suckers: Shoots that grow at the lower part of the trunk.
Training Systems for Grapes
Of the many different training systems for grapes, the high cordon system, or high wire system, is viewed as a good choice for home gardeners because it’s simple, and it works well for American table grape varieties, which grow downwards, unlike European grapes, which have an upward growing direction. And it gives you the option of growing grapes in a row, or as an arbor. The high cordon system requires a trellis with posts eight feet long, with two feet buried in the soil. End posts should have a diameter of four to six inches, and posts within the row a diameter of three inches. Spacing between the grapevines should be seven to eight feet in the row. In the high cordon system, there is only one wire at the top. Because a grapevine must support a lot of weight, make sure to select a 12.5-gauge high-tensile wire. After you plant your grapes, during the first year, it’s all about establishing the plants. If you don’t want to install a permanent trellis yet, put at least a wooden or metal stake in the ground, and tie the new grapevine to it to ensure it’s growing into a straight trunk. You can start training the vines when new shoots have turned into woody canes with a pencil-size diameter. Select two of the strongest, healthiest canes and tie them to the wire, one cane in each direction, using an elastic material such as a piece of cloth, rubber band, or vinyl tape.
When to Prune Grapes
Pruning can be done any time between the start of dormancy and late February or the beginning of March depending on your location. Make sure that the grapes are fully dormant when you prune them. After New Year is usually a safe time. If you prune grapes too early, the vine might be prevented from going into dormancy, which could lead to cold injury. Pruning later in the dormant season has the advantage that the pruning cuts, which are injuries, will expose the grapes for a shorter time to diseases such as grapevine cankers. Once the grapevine breaks dormancy, those cuts will heal.
How to Prune Grapes
Like with grape training, grape pruning can be a bit intimidating due to the sheer number of pruning methods. The goal, however, is always the same: to remove 85 to 90 percent of all one-year-old wood. How much you prune is determined by how vigorous your grapevines are growing. American grape cultivars have the lushest foliage of all grapes, followed by French-American hybrids. European grapes have the least foliage. Between the basic two types of pruning, cane pruning and spur pruning, cane pruning gives you the highest yields and best table grapes. The following pruning can be followed for mature grapevines, which is any vines three years or older. To cane prune, remove suckers and all cane growth except new one-year-old fruiting canes. You can easily distinguish new canes from old ones by looking at the bark. New canes have smooth, reddish to bronze-colored bark and buds. Old canes have a grayish and rather shaggy bark and no buds. Next, prune the new canes so they become either fruiting canes for this year, or renewal spurs, which will become fruiting canes next year. Cut each fruiting cane back so that 15 buds, or three to five nodes, remain on the cane. The goal is to have 50 to 80 buds per plant. Renewal spurs should be at least pencil size in diameter at the cut end. Select suitable canes and cut them back so they only have one node left. Try to space these spurs evenly along to cordon to ensure balanced growth and shape of the grapevine. Don’t worry about pruning your grapevines too much. Most home gardeners do not prune grapes enough. And if you really went a bit overboard with your pruners, just keep talking good care of your grapes by giving them nutrients and water in a dry spell, and monitor them for pests and diseases. They will come back in full force the next year.
