Pruning grapevines ensures proper training and optimal fruit-to-foliage balance. North Carolina falls into the USDA Hardiness Zones of 6b through 8b. This means that the temperature throughout the state drops below freezing each winter. With these harsh conditions, the best time for pruning grapevines is early spring, once the temperature gets above freezing.
Determine which canes are for fruiting. Optimal fruiting canes are close to the trunk's head and have good sun exposure. The best canes to choose will have firm, brown wood that is pest- and disease-free, be at least 1/4 inch thick and have internodes spaced at 3 to 4 inches. Select one fruiting cane on each plant. Leave this branch uncut for now.
Select a renewal spur that is positioned close to the fruit spur. Trim this branch back to one or two buds. Buds are the little bumps on the branch that will produce leaves in the spring.
Trim away all other canes to their last nodule from the trunk. A nodule is a little knot that forms along stems.
Calculate the necessary amount of buds to keep on the fruiting cane. The most common calculation is 20 buds for the first pound of pruning weight and 10 buds for every cane after that. According to The Mid-Atlantic Winegrape Grower's Guide, 20 buds should be left per pound for Chardonnay, Riesling, Cabernet Sauvignon and Cabernet Franc in North Carolina to ensure an adequate amount of foliage.