09/06/2012 at 17:18
As you you have only just planted it, the most important thing is to let it develop good roots. If you see any miniature bunches of grapes developing this year, pinch them off, so that all the energy of the vine goes into producing good roots and the main vine stem itself. If you don't do this and let any grapes develop this year, it will weaken the young vine and it could take a few extra years for it to establish properly. I would probably remove all fruit next year, too. It is tempting to let grapes develop, but patience will be amply rewarded in the long run!
In the middle of Winter, long after all of the leaves have fallen off, you should prune off any sideshoots that develop each year to two buds (ie leave a short section of each sideshoot from the main stem with two buds on it.) Never prune a grape vine in spring when it just starts regrowing, as the sap will leak from the cut for a very long time and harm the vine (they can actually 'bleed to death'.)
When it is three years old, you can let a few bunches of grapes develop. When you see a bunch, you should snip off the end of the branch, leaving two or three leaves beyond the grapes before where you cut. Don't let more than one bunch of grapes develop on each sideshoot or the grapes will not grow very large.
I have a very old vine that is more than 20 meters long and always treat it like this with excellent results - enough fruit to make my own wine!