This was the first year that our two grape vines bore fruit. We have harvested four huge baskets off of these two vines. They are a pink blush grape called Candace. The grapes remained small, about as big as a garbonzo bean, but were extremely sweet. My question is, are grape clusters supposed to be thinned as we do our peaches? What can I do next year to increase the size of the grapes? We irrigate, mulch and fertilize.