When growing grapes one of the most important aspects of maintenance, grape pruning, is often overlooked, leading to vines that produce numerous weak shoots and small, poorly ripened fruit clusters.
Grape vines should be pruned annually which allows the plant to focus it's stored reserves into a limited number of buds and shoots which will yield larger, good quality, well ripened grapes. Since grapes only produce fruit from buds sprouting on one year old canes, it is important to encourage healthy new growth each year by removing the previous year's fruiting canes.
Optimally all canes should have good sunlight exposure which promotes wood maturation, bud fertility and maintains overall plant health which helps to combat disease.
Pruning is done while plants are dormant, with the best time being January into early March. Although pruning can be done anytime while that plant is dormant (between leaf drop and bud break), waiting until after winter's coldest period has passed limits that amount of corrective pruning required to compensate for any cold damage the canes may have suffered.
When pruning grapes keep in mind that you will be removing up to 90% of the previous season's growth, so this exercise is not for the faint of hand!
Basic Grape Vine Anatomy
Trunk - main growth that supports the entire crown
Crown or Head - top most branching point of the main trunk where cordons, arms, etc. extend
Cordon or Arm - braches that extend from the main trunk and are usually permanent, additional arms extend from these
Fruiting Cane - 1 year old cane from which current year's shoots will produce fruit
Spur - short side stem developed off an arm or cordon from which fruiting canes sprout
Renewal Spur - spur used to sprout new fruiting canes
Pruning Methods - Cane Pruning:
This is the most common method of pruning a vine where several canes (2-4) from the previous season are selected and trained along a support (trellis, arbor, etc.). All other shoots are removed and the new fruiting shoots will sprout from the selected canes in spring. To identify those to be kept you should select canes that have firm mature wood between 1/4 to 1/2 inches in diameter with enough buds (15-20) to work with. Buds should be free of visible damage or disease and no more than 3-4 inches apart.
Fruiting canes and renewal spurs should be selected from positions close to the head which prevents the cordons from becoming too long, leaving nonproductive gaps in the canopy. After selecting fruiting canes you will select another well-positioned cane to be used as a renewal spur which is pruned back to one or two buds.
The remaining canes and growth are removed. Pruning cuts for fruiting canes are made through the next node (bud) beyond the retained buds, so that the enlarged portion of the node prevents the tie from slipping off. Finally carefully bend cane onto support and tie off.
Pruning Methods - Spur Pruning
Cordon trained vines (see image below) are typically spur pruned. All fruiting and renewal spurs arise from the cordons, to ensure proper spacing and selection of canes use the same criteria described under cane pruning.
Once canes are selected, remove all growth from the previous season. To create a fruiting spur, selected canes are pruned back to 2 to 4 buds depending on the desired crop level or fruitfulness of the vine. In all other aspects treat this method as you would cane pruning.
For More Information:
For more information about grapes and grape vine pruning, please contact the helpful horticulturists at Art's Nursery by visiting us in person or calling 604.882.1201. We carry a large selection of grape vines for both wine making and fresh eating. Best selection is available in mid to late spring.