Grapes fruit on lateral shoots on year-old canes. All grapes require heavy pruning to produce fruit. Leave two whole canes from the previous growing season and two canes cut back to two buds. The short canes will form replacements for the others when they are through fruiting. When fruit forms from side growth along this cane, clip the cane off beyond the next set of leaves. You thereby encourage two new canes that will bear fruit the following year.