Is it too late to prune my grapes being it is mid-March? I didn't have a chance to prune this winter, and the vines are about 7 years old. I live in Grants Pass, Oregon.
Grapevines should be pruned while dormant (in winter) to make sure the vine bud numbers are reduced and the amount of growing points (from the buds) are in alignment with the intended training system. Ideally, vines are pruned from December through February in Oregon. However, vines may be pruned in March.
However, the vines are getting closer to the start of the growing season (bud break), and the later you prune, the greater chance of delaying bud break. This may be desirable in some regions where spring frosts may damage the small growing shoots at bud break. Also, delayed pruning is beneficial for preventing grapevine trunk disease infection.
If your vines have not yet started to grow (bud break), then you will have little concern for your vines. They may be delayed a bit (5-7 days) for bud break, but that should not be problematic for your vines. If you see buds starting to grow before you start to prune, take care not to damage the buds while pruning or tying down canes.