Pruning is an annual practice for table grapes, allowing the vine to direct energy toward producing fewer, higher-quality fruit clusters. An unpruned vine quickly becomes an overgrown tangle, leading to reduced fruit production and lower sugar content. Proper pruning manages the vine’s size, improves productivity, and ensures the plant’s longevity. This structural work aims to maintain a balance between vegetative growth and fruit production.
Essential Timing and Tools
Pruning must be performed during the dormant season, typically in late winter or early spring before the buds begin to swell. Pruning before bud break minimizes the loss of energy reserves stored in the roots and wood, even if the vine “bleeds” sap from the cuts. Waiting until after the buds have opened can stress the plant and damage the tender shoots that will produce the current year’s crop.
Proper tools are essential for making clean, precise cuts that heal quickly and reduce disease risk. High-quality, bypass-style hand pruners are best for cutting pencil-sized, one-year-old wood. Bypass loppers provide the leverage needed for removing thicker, older canes or small arms. Always sanitize tools with rubbing alcohol or diluted bleach between vines to prevent spreading pathogens.
Understanding Grapevine Structure
Effective pruning requires understanding the permanent and temporary structures of the grapevine. The Trunk is the main, upright, permanent stem connecting the root system to the upper vine structure. Extending from the trunk are the Cordons, which are permanent, horizontal arms of two-year-old or older wood trained along a trellis wire.
Fruit is produced on shoots that grow from Canes, which are the woody, brown, one-year-old growth from the previous season. A Spur is a cane pruned back severely, usually to only two or three buds. Buds are small, compressed growing points located at the nodes along the cane, containing the potential for the coming season’s shoots, leaves, and fruit clusters.
Choosing and Executing the Pruning Method
The pruning method depends on the specific table grape variety, as some grapes only produce fruitful buds farther down the cane. The two primary systems are spur pruning and cane pruning, each establishing a different permanent structure. For both methods, it is recommended to remove about 90% of the previous season’s growth to focus the vine’s energy.
Spur Pruning
Spur Pruning is used for varieties fruitful from the first few buds of the cane, relying on permanent cordons established along the trellis wire. All one-year-old canes growing along the cordon are cut back to short, two to four-bud sections called spurs. These spurs are typically spaced four to six inches apart along the cordon, and the resulting shoots will bear fruit. This method is structurally simpler because the main arms remain year after year.
Cane Pruning
Cane Pruning is necessary for varieties where the most fruitful buds are located farther from the base, such as ‘Thompson Seedless’ or ‘Flame Seedless.’ This system does not rely on permanent cordons, instead removing nearly all previous season’s wood each winter. One or two pencil-thick, one-year-old canes are selected, laid horizontally on the trellis wire, and pruned to 10 to 15 buds. A one- or two-bud renewal spur is left close to the trunk to produce the next year’s fruiting canes, ensuring continuous renewal.
Seasonal Growth Management
After dormant pruning, several management tasks are necessary during the growing season to ensure fruit quality. Shoot Thinning begins in spring after budbreak, involving the removal of excess, non-fruiting, or weakly growing shoots. The goal is to retain an optimal shoot density, generally four to six shoots per foot of cordon, preventing overcrowding and improving air circulation.
Later in the summer, Hedging or Topping involves cutting back the vigorous, upward-growing tips of the shoots to manage the canopy size. This practice redirects the vine’s energy from vegetative growth toward fruit development and ensures that sunlight penetrates the fruit clusters and leaves.
Finally, Leaf Removal around the fruit clusters is performed strategically, usually just before the grapes begin to change color (veraison). Removing a few leaves directly shading the clusters improves air movement, reduces disease risk, and enhances the color and sugar development.