How should a long neglected grape-vine be pruned?

Question

Our recently purchased home has a lot of old fruit and vegetable plantings that were mostly left alone for the past few years. Among these is a set of three grape vines on a group of metal trellises. We've cleared out the weeds that were growing around the vines, as well as some competing climbing plants that had gotten up onto the trellis and intertwined themselves with the grape pretty badly and took over a big portion of the trellis.

So right now the grape trellises are pretty clean and the vines appear to be healthy, although they're very unevenly distributed over the structure. What should we do now to encourage future growth and get the vines to spread out? Are there any companion plants or other fertilization techniques we should look into. We'd like to avoid chemical fertilizers if possible.

Answer 1

So you know, I do not have personal experience with this.

I did, however, find an excellent website which I suspect you'd really prefer to have me summarize. :)

It's year-old growth which produces flowers and then grapes. Two years or older wood does not produce fruit, and will have loose, shedding bark that the younger canes will not have.

Grape vines should be pruned while dormant. In general, pruning in late winter or early spring (before budding starts) allows the plant to handle winter stresses and losses better.

The plant will fail to ripen the grapes if you allow it to keep all of the 200-300 buds on the year-old canes.

In order to select which to keep, it's helpful to know that, within a given cultivar, darker colored canes indicate good light exposure during the previous growing season and greater bud fruitfulness. Buds from these canes will also be more winter hardy. Small diameter -less than 1/4 inch - canes should not be kept because of their inferior productivity and bud hardiness.

I suspect that you will need to do pruning in order to get the vines to spread, based on the above guidelines.

As far as companion plants, according to Wikipedia, grape vines like hyssop for stimulating growth, and geraniums attract pests away from them. More about grape companion planting is here.

It sounds like grape vines don't need much for fertilizer once established, especially if the pruned leaves and shoots are left to decompose. More information is available here.

Hopefully this is a good starting place for you!

Answer 2

Since you've already accepted a nicely sourced answer, I'll contribute some unsubstatiated tradition (i.e. what I was paid 5 cents an hour to do as a kid).

1. Prune near the end of the cold season, not in the summer.
2. Prune so that you leave 4 buds from the old trunk.

-My Grandpa John Montgomery

Answer 3

Let me add what I would do, since I have a couple of vines at home: At first, just choose some strong "main" branches of the grape vine that are healthy, and prune everything else down to 2 or three buds.

These should then regrow a lot (if the plant is healthy) the following year, and if you want the plant to spread then keep the strongest, most vigorous ones to build a structure of strong grape vine trunks, if you know what I mean.

Anything that isn't part of the main structure (the base branches) can and should be cut back every year to promote year-old wood and thus fruit, I think.

It's a lot of work though. If you want them to be ornamental none of this is necessary. :D