Last fall, I wanted to put in some good bare root stock to start a concord grape vine (climbing a pergola). I was having a hard time finding a company that would send me stock in the fall, and in the meantime I saw a longish 2 year vine still for sale at a local garden nursery. I bought it. When I pulled it out of the pot, it was slightly rootbound; in addition, the main wooded vine is both cut at the top and less than pencil thin (which I understand is ideal). So here is my question: should I give this plant up as a wash (pulling it out now); grow it for a season and see what happens; or cut it back radically to try to get a main stem that can widen out to more than pencil thin. I guess the question is how to rehab a slightly root bound grape vine (that's now been in the earth about 6 months and is leafing out more or less fine) that has a main lead that's long but thin. Save it, dump it, or trim it? I've never grown grapes before, so any tips you may have would be appreciated. Although I'd hate to start over, I do want a strong vine for many years and don't want to nurse along something that will never do well.

Thanks!