• Once the vines are mature and start producing fruit, you will want to prune out all the two-year-old wood back to the main trunk.  The two-year-old dormant canes will be a light gray color with peeling bark.  Typically there will be several shoots of one-year-old fruiting wood coming out from the trunk in each direction on each support wire. The one-year-old growth will be a chocolate brown color.  These are the canes that will produce fruit in the coming year.
• Choose the strongest one of each of the fruiting vines, one going in each direction on each support wire, to leave for the upcoming season.  If these fruiting vines are exceptionally long and spindly at the ends, you can prune them back until the wood is about the size of your little finger.  The stronger the wood, the better it will be able to support fruit. The recommended number of buds on the new fruiting canes is at least 8 to 10.  The rest of the fruiting vine can be pruned back flush with the main trunk except for where you want renewal spurs for the new growth the following year.  It can be tempting to keep more of these one-year-old canes, but doing so will result in smaller fruit.  After pruning, you will want to remove all the old canes you have trimmed out to reduce fungal diseases.

Renewal Spur Pruning

• When learning how to prune grapevines, it is important to understand how to get new growth for the coming year. Renewal spurs are attached to the main trunk, and this is where the new canes will grow this coming year that will produce fruit clusters the following year.  You will want to leave a renewal spur as close to the main vine as possible. One pointing in each direction on each support wire.  You will only prune these back to the first node or bud along the cane, usually about 3-4” from the main trunk.  Once cut here these will branch out from there and grow new shoots for the coming year.  Because I live in zone 4, I sometimes leave an extra renewal spur if there’s more than one, in case of winter damage.