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 afterwards.
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.
As much as possible, prioritize your pruning schedule according to the relative susceptibility to winter injury of each variety.
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.
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Timely Viticulture is designed to give those in the Maryland grape industry a timely reminder on procedures or topics they should be considering in the vineyard. To view other topics you can go to the Timely Viticulture page that is located on the Grapes and Fruit website.