Balanced Pruning 2: Timing
Pruning a vine causes it to deacclimate similarly to a warm spell, so do not prune (especially very sensitive varieties) when you know you will experience very serious cold shortly afterward.
The best thing to do is to try to delay pruning as long as practically possible. If you could accomplish all of your pruning in the last two weeks of March that would probably be best, although that is typically not enough time for most commercial vineyards.
Delayed pruning also allows for better estimation of winter injury to buds so that adjustments in bud number can be made.
If you cordon prune it is sometimes best to “rough prune,” maybe down to 12-16 inch spurs initially and then down to your final 2-3 bud spurs.
- This “rough pruning” will inhibit the development of the critical count buds on the spurs you are maintaining compared to cutting directly back to a 2-3 bud spur.
- For early budding varieties (Chardonnay) pruning to the final 2-3 bud spur is accomplished only after the danger of late frosts has passed.
As much as possible, prioritize your pruning schedule according to the relative susceptibility to winter injury of each variety.
- Prune vines on the best sites first and the worst sites last.
- Prune American varieties first
- Followed by the cold-resistant hybrids (Foch, Baco Noir, Seyval)
- Followed by the more cold-sensitive hybrids (Vidal, Traminette Chambourcin)
- Save the vinifera for last, doing the least cold-sensitive first. (Riesling, Cab Franc)
- And the more sensitive vinifera (Merlot?) for very last.
- You may have developed a feel for the “relative” cold sensitivity of the vinifera varieties at your site based on experiences in test winters. Remember, the relative hardiness may change from region to region and vineyard to vineyard.
Also, early budding varieties (Chardonnay, Cab Franc) should be pruned as late a possible to delay bud break and avoid late frosts. Rough prune first as described above, and only make final cuts down to count buds after all danger of frost has passed.