Grapevine Training and Pruning for Optimal Growth and Harvest
Grapevine Terminology
Before delving into the intricacies of training and pruning grapevines, it’s essential to familiarize yourself with the key terms used in this context:
- Trunk: The main, upright stem of the grapevine.
- Shoots: The new, green growth on one-year-old wood, bearing leaves, tendrils, and flower clusters.
- Canes: Mature, woody parts of the grapevine that have produced fruit or are capable of bearing fruit (fruiting canes).
- Cordons: The horizontal “arms” of a grapevine that extend from the trunk, often supported by wires.
- Spurs: Short, one-year-old canes pruned to retain only two to four buds, which will develop into shoots and eventually fruiting canes.
- Renewal Spurs: Spurs pruned back to a single node to generate shoots for next year’s fruiting canes.
- Suckers: Shoots that emerge from the lower part of the trunk.
Training Systems for Grapes
Grapevines can be trained using various systems, but the high cordon system is particularly suitable for home gardeners growing American table grapes. This method involves:
- Installing a trellis with posts and wires at a height of eight feet.
- Selecting two strong, healthy canes during the first year and tying them to the wire, one in each direction.
- Establishing a permanent trellis and continuing to train the vines by tying new canes to the wires as they develop.
When to Prune Grapes
Pruning is crucial for grapevine health and productivity. The ideal time to prune is during dormancy, typically between the start of dormancy and late February or early March, depending on your location. Avoid pruning too early, as it can prevent the vines from entering dormancy and increase susceptibility to cold injury.
How to Prune Grapes
There are two main pruning methods: cane pruning and spur pruning. Cane pruning is generally preferred for American table grapes and involves:
- Removing suckers and all cane growth except new one-year-old fruiting canes.
- Pruning fruiting canes to retain 15 buds (three to five nodes) each, with a target of 50 to 80 buds per plant.
- Selecting suitable canes and pruning them back to a single node to create renewal spurs.
Tips for Successful Pruning
- Prune aggressively to remove 85 to 90 percent of one-year-old wood.
- Adjust pruning severity based on the vigor of your grapevines.
- Space renewal spurs evenly along the cordons for balanced growth.
- Don’t be afraid to prune heavily; most home gardeners tend to under-prune.
- If you over-prune, provide extra care to the vines by ensuring optimal nutrition, watering, and pest and disease management.
Additional Considerations
- Grapevine Growth Habit: American grape cultivars have abundant foliage, while European grapes have less.
- Plant Part Morphology: New canes have smooth, reddish to bronze-colored bark and buds, while old canes have grayish, shaggy bark without buds.
- Pruning Techniques: Cane pruning involves retaining fruiting canes, while spur pruning focuses on creating renewal spurs.
- Common Mistakes to Avoid: Pruning too early, under-pruning, or not spacing renewal spurs properly can hinder grapevine growth and productivity.
By following these guidelines for grapevine training and pruning, you can establish healthy, productive vines that will yield abundant harvests of delicious grapes for years to come.