if the fruits are edible and you want to eat them, then you can remove a little foliage to let the sun in to help ripen the grapes. Pruning of a vine is usually done when the plant is dormant otherwise it 'bleeds' a lot of sap. I prune mine on Xmas day, its dormant I escape from kitchen duties for an hour or two into the greenhouse. Certainly needs pruning before any buds break in spring. Mine gets a hard prune as it only has limited space. so its up to you how much you remove.

The 2-year-old grape vine won't be producing viable grapes yet as it takes 3 years to train a vine. Pruning a vine correctly is the most important thing to get right if you want to grow viable grapes.

There's lots of information on the internet about pruning a grape vine and at first I found it hard to get my head round it as it seemed to be very complicated. The easiest way to remember it is that grapes will grow on shoots coming off what was last years green growth then you won't go far wrong.

I have a vine growing in my greenhouse and this year it is producing what I estimate to be 50 - 60 lbs of grapes.

What I do is prune it back to just above 2 buds on last years growth. These two buds will form the shoots and laterals for the next seasons growth, the vine will grow prolific and should produce lots of grapes. If you are growing it over a pergola then I would prune to 3 or even 4 buds if you want the vine to grow more and give some shade. However, this will probably be detrimental to grape growth especially as they are rather young vines.

The pruning should be done in December/January when the vine is dormant. Remove all the dead leaves and pull off any little bits of woody tendrils first and you will have a nice clear view of where to prune your vine.

If you need further information about pruning I would suggest you visit the RHS website as they have good information on vine pruning.

Hope this helps?