Several factors influence the choice of trellis for a vineyard. These include the grape cultivar’s growth habit, the expense of the trellis, productivity, how well the trellis is adapted to mechanized operations, labor availability, and the trellis’s effect on vine balance.
The growth habit of grapevine cultivars influences how easily they can be trained to a particular trellis. Low-cordon trellises, such as the Vertical Shoot Positioned (VSP) or the Lyre systems, are best suited to cultivars with upright growth habits. This includes most Vitis vinifera cultivars and many hybrids.
Native grape cultivars such as Norton, Concord, and Catawba have trailing growth habits and are best suited to high-cordon trellises such as the Single Curtain Bilateral Cordon (SCBC) or the Geneva Double Curtain (GDC) systems. Many hybrid cultivars with semi-upright growth habits can be easily trained to either high- or low-cordon systems.
Expense is another important factor in choosing a trellis. This includes both the cost of materials and installation and the cost of annual maintenance. An SCBC trellis, which utilizes only a couple of wires per row, will, given the same between-row spacing, cost less than a VSP trellis, which has 5-7 wires per row. This is due both to the cost of wires and the labor expense for installing them. Horizontally divided trellis systems such the GDC or Lyre trellises are also more expensive due to materials and installation costs.
The influence of the trellis on yield per acre should also be considered. A GDC trellis can increase yield per by as much as fifty percent compared to a SCBC trellis, and even more over a VSP trellis. It does so by increasing the amount of bearing surface of the vine per acre exposed to sunlight. However, vineyards with a single cordon trellis and narrow row spacing may be nearly as productive as vineyards with wider row spacing and a horizontally-divided trellis such as the GDC.
If there is a possibility that the vineyard will be mechanized at some point, then a trellis’s adaptability to mechanization is also a factor to consider. Every operation from pruning to harvest can be done or partially done mechanically. Some trellis systems are more adaptable to mechanical operations than others.
Finally, vine vigor and the trellis’s influence on vine balance should be considered. Vine balance is carrying the highest yield the vine can fully ripen without reducing vine vigor and winter hardiness. In a balanced vineyard, each vine has enough room to express its capacity for growth through medium-sized shoots and most of the leaves exposed to the sun at some time during the day. Trying to force a vigorous vine to grow on a trellis that does not allow it to express its vigor and does not display the majority of foliage to the sun causes serious shading within the canopy and can lead to reduced productivity and reduced fruit quality.
