Answer: You can prune grapes at any time, providing you don't mind losing the fruit. Once the sap begins to flow your grapevines will weep for weeks after pruning, but it shouldn't be cause for alarm and it won't hurt the plant. I'd go ahead and prune now, with the idea that some of the bearing vines will have to come out, too. If your grapevines need a complete overhaul, you can wait until the dormant season to really cut them back.
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