Should You Trim New Growth on Grapevines During the Growing Season?

When to Prune Grapevines

• Grapevines should never be pruned during the growing or fruiting season. This will cause injury and shock to the plant which may interfere with healthy growth and fruiting. Instead, prune grapevines during the dormant season. This season begins in late winter and extends as far as early spring. If pruned in early spring, there will be bleeding of sap from the vines, but this will not be harmful.

Grapevine Training Systems

• Two common types of grapevine training systems are the cordon and head training systems. Which type you have will alter your pruning strategy slightly. In cordon training, either two or three wires have four- or six-year-old vines trained onto them. There will also be four or six new budding vines that will be left on the grape plant to provide for next year's growth. In the head training system, two vines are selected to be the main vines and the other vines can be pruned.

How to Prune Grapevines

• When pruning grapevines, make clean efficient cuts. You will want to prune away many of the shoots or "canes" that have an age of a year or older. This is because it is the younger shoots that actually fruit ,and you will want to maximize fruiting while leaving a few older vines to support the plant. In the head training system, this will always be the two main vines, while in the cordon training system, you will maintain four or six older vines, with the rest being removed. You will also want to somewhat limit new growth, as too many new vines will actually cause reduced grape production. A ballpark figure of 40 to 50 new buds per vine should be retained, with the rest pruned away.

Tools Used for Pruning Grapevines

• No matter what tools you use to prune your grapevines, it is important that they be extremely sharp. This will encourage clean cuts that will heal better. Lopping shears are useful for pruning hard-to-reach areas. For work in close quarters and for new growth, hand pruners are preferred. For very old, tough growth, a hand saw will be necessary.