[Hillbillypop]

Hi
Last year I planted a vine in my 8x8 greenhouse in return it geve me 9 bunches of lovely black grapes weighing in at just under the pound each. I now have the bug to grow more and make my own wine.
Now the question is i have a 20x 20 plot to put a tunnel on  How many vines would you recomend and do you see any down fall
regards
Will