Autumn pruning of grapes: when, how and what to leave before winter

1Why prune grapes in autumn

Grapes bear fruit on shoots that have grown on last year’s cane. So every year the vine has to produce fresh growth, and old and surplus cane has to be removed. Pruning maintains the shape of the vine, determines the cane that will carry the crop and keeps the vine from getting too dense.

In autumn there is also a practical reason: cover varieties have to be laid on the ground and covered, and in a dense vine with long, tangled shoots that is difficult. The neater the vine, the easier it is to cover and the less room there is for rot and rodents under the cover. About the process itself, read the article “How to cover grapes for winter”.

2Autumn or spring: what the sources say

It is important to be honest here: there is no single opinion, and it depends on the climate and the variety.

• The eXtension service (USA) notes that pruning is done from leaf fall until bud break. At the same time it warns that autumn pruning can raise the risk of winter injury, so in cold regions it is better to wait until the hardest frosts have passed, to assess the damage and adjust the number of buds.
• Penn State Extension says the same: autumn pruning increases the risk of cold damage, and with early pruning you cannot tell whether frost has damaged the buds. For such cases there is also two-step pruning: in winter the cane is shortened only partly, and the job is finished after bud break.
• In Ukraine, autumn pruning is widely practiced for cover varieties: the cane has to be laid down and covered before frost, and it cannot be pruned under cover. So a compromise works here: in autumn remove what is clearly surplus and leave a reserve, and finish the budget of buds in spring.

For no-cover varieties in cold places it is more logical to limit yourself to minimal cleaning in autumn and do the main pruning at the end of winter.

3When to prune

• After leaf fall. While the leaves are green, the vine is still storing nutrients. Wait for natural leaf fall, and then a few more weeks. Domestic publications advise the same: about two to three weeks after leaf fall.
• Before cover. Finish pruning before you lay the cane under cover.
• In dry weather and without hard frosts. Frozen cane is brittle and breaks. For most regions of Ukraine this is usually November.
• Not too early. While the leaves are still green, you should not prune: the cane is still building reserves, and wounds take longer to heal.

4Which cane to remove and which to keep

Remove in this order:

1. Diseased, broken and dead caneTake off mummified clusters separately.
2. Unripe caneCut the green, soft section at the end of a shoot that did not manage to turn woody back to the woody part.
3. Weak and thin canesShoots thinner than a pencil and hollow (“straw”) ones are pointless to keep.
4. Cane that bore a crop this yearIt is already two years old, and next year there will be no new berries on it. The shoots that grew this summer will bear fruit (in most training systems these are the ones that are kept).
5. Surplus shoots that crowd the vineLeave as many as you can place evenly on the trellis.

Keep:

• Healthy, well-ripened shoots, evenly brown, with dense wood.
• About as thick as a pencil. Penn State Extension gives a guide of 1/3–3/8 inch, that is, 8–10 mm. Very thick “water shoots” are not the best choice either: they can be less frost-hardy.
• A small reserve. One or two extra links of cane in case some of the buds freeze.

5How to cut

• Tool. Sharp, clean pruning shears. If the vines had diseases, wipe the blades with alcohol or another disinfectant between vines.
• The cut. Smooth, with no split wood. Leave a small “stub” above the last bud you keep, about 2–3 cm, so the bud does not dry out. It is best to cut in the middle of an internode, not at a node.
• Large cuts. On old wood large wounds heal with difficulty, so try to get by with small cuts.
• Waste. Take diseased cane, leaves and mummified clusters off the plot or burn them. Healthy, well-ripened cane can be used for cuttings.

6How many buds to leave

The exact number depends on the variety, the age of the vine and the training system. So here we give a principle, not a number: in autumn leave more than you plan to have in spring. Penn State Extension advises leaving extra buds as insurance against freezing: if some buds winter-kill, the reserve lets you avoid losing the crop. After bud break and an assessment of the damage, finish the budget of the vine: leave the needed number of shoots and remove the surplus.

Young vines in their first years first need to develop cane and roots, so pruning on them is minimal: we will talk about training a young vine separately.

7What to do next

1. Clear away leaves and mummiesfrom under the vine and from the trellis.
2. Tie upthe cane you left so it is easy to lay down.
3. Treat if neededIf you do an autumn preventive treatment, use the preparation according to the manufacturer’s instructions: see the label for dosages and timing, we do not give them in the article.
4. Coverthe cane: timing and methods are in a separate article about cover.

8Frequently asked questions

9Sources

• Dormant Cane and Spur Pruning in Bunch Grape Vineyards, Penn State Extension: timing, the risk of autumn pruning, choosing cane, reserve of buds.
• Pruning Grape Vines: An Overview, eXtension (Grapes): the pruning period, the risk of winter injury, two-step pruning.
• Eyes are afraid, but hands do the work: how and when to prune grapes in autumn, Vikna (in Ukrainian): practical timing in Ukraine (2–3 weeks after leaf fall), used as a guide.

The article is based on university handbooks and practice; for your variety and region the timing and number of buds may differ.