Answer: You could allow them to grow unpruned and continue to build strength, or you could prune them back lightly. You could also begin training them to fit your arbor. Grapes are normally pruned back very hard every winter to encourage fruit production. This may or may not be part of your plans for these vines, but another reason for the pruning is to thin them to encourage air circulation and thus discourage fungal infections. For aesthetics, you might want to develop a "trunk" at each leg of the arbor, then prune the vine short every year just at the top of the arbor so that the new growth grows along the roofline.
Q&A Library Searching Tips