By Xander Rose
Raintree sells some great fruiting vines that can be trained to arbors, fences, walls, and trellises. Vines require training because they are not as upright as trees. A basic understanding and practice in how to prune and train them will yield more and better fruit than letting the plants run wild.
Working at Raintree has exposed me to how some of the vines we sell are pruned and trained to trellises. I have also had the experience of repairing trellises. We grow kiwis, grapes, and akebia on-site for aesthetics, cutting material for making new plants, fruit, and education. Grasping something of the biology and natural history of the vine in question will make pruning and training much more intelligent, efficient, and satisfactory. If grapes aren’t pruned correctly, they will produce less fruit! In general, fruiting vines benefit from fairly hard pruning.
As discussed in another blog post, “Espalier and Other Intensive Pruning and Training,” in horticulture a cordon is the concept of a horizontal branch line off of which fruit is produced. Kiwi is grown so that it has a single main trunk rising four or five feet to a trellis composed of three or more parallel high tension wires. Two cordons of kiwi vine grow in opposite directions along the trellis. Kiwi vines can be very vigorous, productive, and heavy, so the trellis structure should be stoutly built and have wire tighteners in it for tightening the wires as they sag over time. Keep in mind that kiwis are dioecious, meaning there are male and female plants and there should be at least one male for every five females in a trellis for adequate pollination.
Kiwi trellises at Raintree Nursery
Grapes can be trained in various ways. A squat (three-foot) stem (trunk) ends up anchoring the vine. One or two levels may be developed from which cordons are maintained and rejuvenated through pruning. One level is simple, with each cordon being like an arm in this “two-arm” system. The cordon can be horizontal or angled upward slightly. Grapevines can also grow over arbors for an aesthetic landscaping effect, though fruit production and harvesting will not be optimized. Grapes can be grown as fans, with cordons spread out like fingers on a hand. Woody canes (wood two or more years old) produce fruit spurs that bear clusters of fruit. Old fruit clusters should be pruned off. Grapes do not need the same level of structural support as kiwis if they are pruned annually when dormant in the winter. Grapes need heat to ripen well, so whatever training system is used, consider how to increase sunlight to the fruit.
Grapes on trellises at Raintree: top, a "two-arm," single cordon system, and bottom, a fan system in development
Pruning grapes not only depends on the training system desired but also on the grapes species and variety. The European or common grapevine (Vitis vinifera) is not as vigorous as the fox grapevine (Vitis labrusca) and the muscadine grapevine (Vitis rotundifolia) of North America, so the American grapes should be pruned harder. European grape varieties can basically be either short-spur or long-spur varieties. Short-spur are more vigorous, so one-year vines are pruned back to just one or two buds (short spurs), from which new shoots and fruit spurs grow the following growing season. Long-spur varieties are less vigorous, so one-year vines are pruned back to three, four, or more buds. Suckers coming up from the base of the trunk should be pruned back, too. If the plant is one variety grafted onto another (with European grafted onto America often being the case), then it’s especially important to keep rootstock sprouts from growing into vines that could overcome the desirable top.
To establish a grapevine on a trellis, let the plan grow as a bush to build its energy reserves and root system in the first year. Then, select vines to establish the cordons and prune out all others. Head the selected vines back and tie them to the trellis. These will become the canes comprising the cordon and from which fruit spurs will grow and more vines can be stimulated as needed.
Akebia vine on a fence at Raintree Nursery
Kiwis, grapes, and other fruiting vines need some structure to grow on and an existing wall or fence can sometimes work well. If not, building an intentional trellis of simple materials is the ticket! Annual pruning helps maintain the vine and increases fruiting.
Happy growing! Because, after all, change is the only constant. -Xander Rose
Gilkeson, Linda. 2011. Backyard Bounty: The Complete Guide to Year-Round Organic Gardening in the Pacific Northwest. BC, Canada: New Society Publishers.
Johnson, Kristan. 2011. “Well-bred Fruit for the Maritime Climate.” Pacific Horticulture Society. Accessed Online 2/13/2021: <pacifichorticulture.org/articles/well-bred-fruit-for-the-maritime-climate-2/>.
Strawbridge, D. and James Strawbridge. 2010. Self-Sufficiency for the 21st Century. Great Britain: Dorling Kindersley Limited.
University of Martland Extension. 2021 “Pruning and Training Grapes.” University of Maryland College Agriculture and Natural Resources. <https://extension.umd.edu/hgic/topics/pruning-and-training-grapes>. Accessed Feb. 13 2021.