I have 2 vines of these grapes. Trees around have grown in the 15 yrs the grapes have been in their place. One is now mostly in the shade. Any chance it can be transplanted to a sunnier spot and survive or should I just buy a new plant?
It can be very difficult to move an established vine. You will be best off taking cuttings, removing the trees in question, or using new plants. They will not fruit as well in shade, so anything to help that will be best.