Pruning your grape vine for winter is an essential part of getting a good crop of grapes the next season. Bernadine Strik--a professor at Oregon State University--states that backyard grape growers do not prune their grape vines enough. You will need to trim about 90 per cent of the previous season's wooden growth to have a successful crop of grapes. If you leave too much old growth on the plant, the grape vine will produce more fruit than it can maintain. This leads to straggly fruit for the next season.
Find the strongest branch on your one year old grape vine. You will make this the trunk of the grape vine.
Cut all of the stems--other than the main trunk--at the bottom of the plant, using pruning shears.
Cut all of the stems from the main branch. Cut each stem as close as possible to the boot without cutting the trunk.
Tie the main trunk to a grape stake.
Wait until spring and cut away growth from the first winter. Leave only the two strongest branches growing from the trunk.
Trim the top of the grape vine to the desired height.
Continue to prune the vine during the spring and winter of year two. Cut every branch except the main trunk and the two branches.
Examine the grape vine in the winter of year three. The two branches will be growing buds. Clip any branch growth off of the two branches, leaving the buds.
Allow your grapevine to grow throughout the summers after winter three. Continue to clip away new growth from the two branches during the winter.