I have a vineyard of about 350 vines, of which about 100 are Sangiovese and 250 are white in Central Italy. These are very old vines, and are really struggling now, especially the red. It has been suggested to me that we could graft new vines on to the old root stock and in that way we could crop new red wine grapes much quicker than planting new vines. Has anyone done this? Do you think it will work? When would you have to do it? Can you graft new red wine grapes stock on to old white grape stock? Where could I buy vines to graft on? I am relying on you all to have all this knowledge, and look forward to your answers.