Don't be afraid to hard prune! You want to remove about 90% of what is there. This may help: Pruning Grapes in Home Gardens.

Are they growing in those buckets? What's that all about?

We had grapes that we planted and forgot. About five years ago, we decided to get serious. We pruned them to about a foot off the ground and built a proper trellis for support. The next year they had grown to the support but gave us no grapes. We expected this, as grapes grow on one year old canes. Since then we have pretty aggressively pruned each year and now get enough grapes for a batch of wine each year. As you don't know how old your canes are, I would err on the side of aggressively pruning.

gardengal48. Thank you! The buckets....I think he put them there to help with weeds, help protect the bottom trunk from our shared farm cats and other animals...but I'm honestly not sure. He likes having them there so I never say anything about them.

Lynda, I'll ask him and see if he knows.