Grapevines (Vitis vinifera) have been grown on arbors for centuries, because the arbors give grapevines a permanent framework to climb. Grape arbors differ from trellises by having ceiling beams for vines to grow on. Arbors provide rustic landscape accents as well. Train new grapevines onto an arbor through pruning, and prune away old vine growth for maximum beauty and grape production.
Prune back a newly planted grapevine for your arbor to only one cane with two or three leaf buds, using clean, disinfected pruning snips. You can train a grapevine onto an arbor anywhere in U.S. Department of Agriculture plant hardiness zones 4 to 10. As the vine sends up new canes, select the strongest cane, and train it to grow up an arbor post by tying it onto the post with twine. This cane will become the trunk of the arbor vine. Prune off the other canes. Do this for each vine you plant for the arbor. Prune the tips off of side shoots to stimulate growth of the trunk during the first year.
Prune off all side shoots at the trunk during the second and third years. Pick one strong cane from the growing head of the trunk to become the cordon or main branch of the arbor vine. Prune off all other canes. Train the cordon to grow along a horizontal ceiling frame member of the arbor by tying it in place with twine. The cordon will develop leafy side shoots called spurs.
Prune back the spurs on each vine cordon to where each spur has two or three leaf buds, starting in the early spring of the fourth year. Prune the spurs before the leaf buds start to open. The pruned spurs will produce new fruiting shoots each year. Prune the previous year’s shoots each succeeding spring. When you finish pruning for the new season, about 90 percent of the previous year’s growth will be cut off.
Thin the current season’s shoots by pruning unproductive shoots that have no grape clusters. A fruiting shoot needs 14 to 16 well-exposed leaves to ripen a cluster of grapes. Thin the shoots in mid-June. If shoots have multiple grape clusters, prune away all but one cluster per shoot.