January is when my local vineyard does theirs. Most vineyards are happy to give advice, so that's a good way to find out, and see it done. Phil J

That's a good time in Nevada, too.

We are in London with a very large outside grape, loaded with good sized bunches this year. See pictures and grape blog guest. They have to sweeten up ?October. Then we enjoy a wonderful display of autumn colour.....November. Then, in order to see clearly where to cut, some leaf drop. Then back to the main 'trunk' right back. It will sprout just the same next spring.

One question to ask yourself is, "What kind of grape is it?" Most European grapes prefer to have practically all of each years growth cut back to 2 buds--called "spur pruning". Some European types, such as 'Thompson Seedless', and most American and American Hybrid grapes produce flowering shoots farther out on the previous years growth, so twigs 10 or 12 buds long should be left every 18"-24" to produce the fruit, while everything else gets a Marine buzz cut to keep it under control. Pruning the first several years involves encouraging a good root system, and developing the main structure you want: to fit a trellis, fence, arbor, etc. Normally, you don't expect much fruit for the first 4 years. Hope this helps more!