Article written by Madeline Wimmer, UMN Extension Fruit Production Educator.
Images: Left: It’s possible for grapevines to be planted and trained without a trellis for their first year. Middle: During the second year of training, grapevine shoots can be grown out from single or double trunks to begin cordon establishment. Right: multiple cordons can be trained onto the fruiting wire during the second year and reduced to one on each side during pruning before the third season starts. After the new canes have been selected to become cordons, the next step is to allow shoots to emerge from each node to become spurs the following year.
Training, trellising, and determining the canopy height
Grapevines require more intensive training than other fruit crops, and they have great flexibility to adapt to various training systems and trellis designs. Training systems (the shape of the grapevine) and trellis designs (the hardware that supports the grapevine shape) go hand-in-hand:
Three-dimensionally trained vines like Geneva double curtain (GDC) and Watson require three-dimensional constructed trellises.
Two-dimensional trellises can support a number of different training styles, most commonly high cordon (HC) and vertical shoot positioning (VSP), but can also support fan training and Scott Henry (a double curtain canopy system) in specific circumstances.
Vine vigor (growth speed) and growth habit (upright, semi-upright, trailing), harvesting technique, and ergonomics can all be considered before selecting a training system and finalizing a trellis design:
Vines that have fruiting zones trained to taller heights are more likely to escape frost damage, but can be uncomfortable to work with when pruning or harvesting.
Some upright growing vines like Marquette work well on a vertical shoot positioning system with upward trained shoots, while others with more Vitis labrusca heritage (ex Brianna) may be hard to train upright.
Cluster appearance is more important for table grapes, and having a system like the Watson that prevents the grapes from hitting against the trellis can promote a better appearance.
Growers who are aiming for high-density production or working on a small lot (ex urban settings) may find benefit from a double canopy system like Scott Henry, which may be less practical for larger-scaled vineyards.
Note: It is possible to change the height of the canopy, or even training system type for already established grapevines. Although there are some limitations and it may require some added steps to adapt a trellis if converting from Vertical Shoot Positioning to High Cordon, or a three-dimensional system like Geneva Double Curtain.
Spur vs cane pruning systems
Most growers in the Upper Midwest currently establish grapes with spurs that are renewed as needed. Since permanent cordons can receive winter damage in cold climates, cane pruning is one alternative to spur pruning. In cane pruning systems, one-year-old canes are selected annually from the renewal zone and retrained along the fruiting wire.
Cane pruning can work well for varieties grown in conditions where bud survival is high at the cane tips, since it works best to maintain 12–15 nodes on each fruiting cane for sufficient yields. Multiple canes can be laid down each year as well.
The alternative is to maintain spur-pruned cordons with the plan to renew spurs, partial cordons, or whole cordons when winter injury is apparent, which can show up as blind wood and reduced productivity.
Year by year process for training grapes
Planting year, trunk establishment (1st year)
After grapes are planted, the goal for the first year is to grow shoots up to the fruiting wire. For high vigor sites, or trellises with shorter heights, this may happen very quickly, but it may take multiple years in other cases and is normal.
Grapes will require a training rod (bamboo or rebar) and manual attaching of shoots to keep them training up and off the ground. The trellis does not need to be constructed this year.
Clusters should be removed from shoots during this year to allow more energy to go into shoot growth.
Cordon establishment (2nd year)
If shoots successfully reach the fruiting wire during the first year, one or two shoots that have become woody (canes) can be retained, with others removed, to become the trunk(s).
During the second growing season, shoots can be grown out of the neck/upper portion of the grapevine.
Traditionally, many growers and educators recommended stripping all other shoots off the trunk below this point; however, the more leaf area there is, the more photosynthesis can occur (as long as there is not too much shading between leaves), which is helpful for overall establishment.
Retaining one sucker from the base of the grapevine is also an ok practice, which can be used to replace a trunk in the case of winter injury. During seasons with no winter injury, this should be removed to prevent excess numbers of trunks from forming.
It’s helpful to finish trellis construction by the end of the second season and install a fruiting wire to train the shoots onto for cordon establishment. Multiple cordons can be trained with the intention of only retaining one by the beginning of the next growing season.
Similar to the second year, clusters should be removed from shoots during the second year to encourage energy into shoot growth and overall vine energy reserves.
Spur establishment (3rd year)
Before the growing season starts, one cordon should be selected for each side, with other shoots removed (renewal spurs can be established on the grapevine neck). Tendrils and lateral shoots should be removed to clean up the cane.
Canes selected to become cordons should be tied down before bud swell begins to prevent knocking on buds (each bud lost can lead to blind wood).
Shoots from each node/bud on the canes can be grown out unless internodes are short (less than one fists length, or 4-6 inches).
Clusters can either be fully removed during the third year, or half-cropped (one cluster per shoot) for vines that are healthy and vigorous.
Trellis training wires, or catch wires should be installed by this year for upright training systems.
Year 4 and onward
Before the growing season begins, new spurs can be established by cutting back canes that grew from the cordon the previous year to 2-4 buds depending on the training system (upward trained shoots should have spurs fewer buds).
A full crop (at least two clusters per shoot) can be yielded this year and onward unless vine health is a concern.
Follow other canopy management practices like shoot thinning, to adjust to an average of 6 shoots per linear foot of cordon, which can be less or more depending on vine vigor.
Infographic: High Wire Cordon training and establishment for the first four years of grapevine training. Infographic created by Madeline Wimmer in 2016, originally published in Wisconsin Fruit News Volume 1 Issue 3.
Resources:
Training systems for cold climate hybrid wine grapes (University of Wisconsin Extension)
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