Grapes (Vitis spp.) are borne on stems that are 1-year-old, grown the previous growing season. Yearly pruning of the vines in late winter allows gardeners to limit the amount of stems that will produce grapes so that they are of the best quality, size and do not weigh down and break the stems. Depending on variety, some plants yield better fruit crops if cane- or spur-pruned. Consult your nursery or cooperative extension office to learn which pruning technique is best on your grapevine. Some people refer to spur-pruning as "cordon pruning."
The First Time Spur-Pruning the Vine
Remove all weak-looking, scrawny side shoots from the grapevine. Make pruning cuts with clean, sharp hand pruners 1/4 inch above the shoot attachment with the main vine arms. Leave the slightly larger, more robust-looking shoots (the spurs) across the entire length of the main vines on the trellis.
Examine the spacing of the spur shoots that remain on the vines. Ensure the spur shoots are between 6 and 10 inches apart the entire length of the vine. Prune off any spur shoots that are closer than that spacing.
Prune back each spur shoot so that only two healthy buds remain on each. Make the pruning cut 1/4 to 1/2 inch above the second bud, counted from the base of the shoot--where it attaches to the lower main vine. During the upcoming growing season, each of these two buds will produce stems that bear clusters of grapes.
Subsequent Year Pruning
Repeat Steps 1 and 2 as outlined in the first section in late winter or very early spring just before the leaf buds swell and unfurl.
Locate the two spur shoots from last season, which will have grown into long vining stems and bore fruits. Retrace the vine back to the area where you pruned 12 months earlier to see how the two buds developed.
Remove the lower-most stem on the spur shoot with hand pruners. This was the lower bud in the two-bud pruning you conducted a year ago. Make the pruning cut 1/4 inch away from the stem's connection to the original spur shoot.
Cut back the remainder of the vines, the "upper lengths" from the original spur shoot, so that you only have two buds. During the upcoming growing season, each of these two buds will produce stems that bear the clusters of grapes.
About this Author
James Burghardt has written for "The Public Garden," "Docent Educator," nonprofit newsletters and for horticultural databases, becoming a full-time writer in 2008. He's gardened and worked professionally at public and private gardens in Colorado, Florida, Minnesota, New York, North Carolina and Pennsylvania. He has written articles for eHow and GardenGuides.