Finding Uncommon and Rare Grapes from World Adventures

You can find gralladina grapes and cranlet grapes on the island with ruins. They are not ready to harvest so it helps to have a fairy make them bloom. You don't have to destroy the ruins as others suggested, just go the the center square room that is broken open and has grass & flowers growing.
All the other grapes can be found on the fenced in farm section next to the Nectary.