Nothing like a threat to get things going!

doesn't work on my wisteria though!

Is your grape vine in a pot or the ground?

My sister did the same with premium bonds and every time she tried to cash them in she won some money. Doesn't work with the lottery for me though.

Grape vines need to be pruned correctly each year to get a good yield and the first 3 years are the most important as these are the years that you need to prune it to train it.

The vine is cut back in December when it's dormant and when trained about 90% of the vine needs to be got rid of. This sounds drastic but it really needs to be done for a good fruit crop.

Come spring when the sap begins to rise your vine will start to grow very fast again and will overwhelm the greenhouse. I have a black German variety in my greenhouse and it produces 20 - 30 pounds of grapes each year.

If you Google grape pruning you will find out the correct way to do it. A bit of advice though. It took me ages to get my head around how to prune the vine. All this talk about where to cut, spurs, canes, second branches, etc, was very confusing then it fell into place. If you remember that grapes will grow on new (green) growth that comes from a branch that was last years new growth then you shouldn't go wrong. I prune all these branches right back to 2 buds and then go back and remove more of the branches right back to the trunk.

The vine looks very bare and a sorry state when it's vigorously pruned, but as I said you will be surprised at how much it grows back in the summer months. I never feed or water it. In fact a few years back I watered it once a week and the grapes all split. This was due I think to too much water so I don't do this anymore and I've never had the same problem.

Hope this helps?