I thought this week we would stand still a little bit at trellising systems and why you would use them. A trellising system determines how the vine will grow, where the shoots and bunches will be positioned, and how easily the vineyard can be managed. It can influence sunlight exposure, airflow, disease pressure, fruit ripening, labour requirements and whether the vineyard can be mechanically harvested.
A trellis provides support for the permanent structure of the vine and gives the annual shoots a framework on which to grow. Instead of shoots becoming tangled and bunches being hidden inside a dense canopy, the vine can be trained into a more open and manageable shape.
Good trellising helps to distribute the leaves and grape bunches evenly. This improves light penetration and allows air to move more freely through the canopy. Better airflow helps leaves and bunches dry more quickly after rain, irrigation or heavy dew, reducing the conditions in which fungal diseases can develop.
Trellising also makes routine vineyard work easier. Pruning, shoot positioning, spraying, trimming, monitoring and harvesting can all be done more efficiently when vines are arranged in neat and consistent rows.
However, the purpose of trellising is not simply to grow the biggest vine or produce the highest possible yield. The main aim is balance. A vine needs enough leaf growth to ripen its grapes properly, but too much growth can create a shaded and humid canopy. Too little growth, on the other hand, may leave bunches overexposed to sun and heat.
When did vineyard trellising begin?
People have supported grapevines for thousands of years. Early growers used trees, wooden stakes, poles and simple frames to keep vines off the ground and make the grapes easier to reach.
Modern vineyard trellising became more common as vineyards became larger and more commercially organised. The availability of wire and treated wooden poles allowed producers to establish uniform rows and train vines in predictable patterns.
In simple terms, vineyard trellising systems can be divided into three main groups:
Low-vigour vineyards
Low-vigour systems are generally found in dryland vineyards or on sites where soils, rainfall or climate naturally limit vine growth.
Bush vines are one of the best-known examples. A bush vine is trained as a low, self-supporting plant without a conventional wire trellis. The short trunk and arms form a cup-like shape, with shoots growing outward and upward. Bush vines are strongly associated with the Swartland and parts of Paarl, although they are also found in Stellenbosch and other older dryland vineyard areas.
Where vines require slightly more support, producers may use simple one-wire or two-wire trellises. These systems keep the vine and shoots off the ground without adding unnecessary cost or complexity.
It is important not to install a large trellis on a site that cannot produce enough growth to fill it. An oversized trellis in a low-vigour vineyard may result in an open, uneven canopy and grapes that are exposed to too much direct sunlight.
I did not forget about “stok by paaltjie” that iconic system where each individual vine has its own stake it is tied against. It has become quite the fashion statement lately, but it performs best against slopes and in poorer soils where growth is not much and you can plant close together.
Average-vigour vineyards
Average-vigour vineyards commonly use three- to five-wire VSP trellises. This is the type of trellis most people picture when they think of a modern South African vineyard. The fruiting zone is positioned along the lower part of the trellis, while the shoots are trained vertically between foliage wires.
VSP systems create a relatively narrow and upright canopy. They provide good access for pruning, spraying, canopy management and harvesting. These systems are commonly seen in Stellenbosch, Paarl, the Cape South Coast and parts of Robertson, Breedekloof, Worcester and the Klein Karoo.
The exact number of wires and the height of the trellis will depend on the site. A three-wire system may be enough for a vineyard with moderate growth, while a stronger five-wire structure may be needed where the vines produce longer shoots.
The main challenge is to avoid overloading the vine. Too many buds or too much crop can weaken the vine and delay ripening. At the same time, allowing excessive shoot growth can create a dense wall of leaves. The trellis and the pruning system therefore need to work together to maintain a balanced canopy.
High-vigour vineyards
High-vigour trellising systems are mainly used in fertile soils, irrigated vineyards and warmer inland areas where vines can produce large amounts of shoot growth.
A small trellis may not provide enough space for this growth. Shoots can become crowded, leaves can shade one another, and grape bunches may remain hidden inside a humid canopy. Larger seven- to nine-wire VSP systems may be used to provide more height and support. Box trellising is also used in vineyards designed for mechanical harvesting, as it creates a structure that is suitable for machinery to move through and work around.
Where vigour is especially high, producers may use divided-canopy systems. Rather than forcing all the shoots into one narrow upright wall, the canopy is divided into separate sections. Examples include the Ballerina (folding some shoots down to form the mentioned Ballerina tutu), Smart-Dyson and Kappe (those ones that look like building roofs, seen a lot where table grapes are produced) systems. More extensive systems include the Scott Henry and Tatura trellises.
Smart-Dyson and Scott Henry systems divide shoots into upward- and downward-growing sections. This opens the canopy and spreads the leaves over a larger area. The Tatura system divides the canopy into two angled walls, creating a broad structure that can accommodate strong growth and potentially higher crop loads. These systems can be very productive, but they are also more expensive to establish and may require more specialised management.
A trellis is a long-term investment and should ideally be planned before the vineyard is planted. The best trellis is not always the biggest or most advanced. It is the one that allows the vine to fill its space without becoming overcrowded, supports the intended crop and makes vineyard work practical.
Articles