Definition - What does Trellis mean?
The trellis is a main part of the vineyard, that gives support and suspends the vines above the ground and allow them to grow in accordance with their growth habit. Vine trellises are made up of posts (wooden or metal) and driven into the ground. They are connected with wire cordons, spaced and built properly for the specific vine type it will attach to. These wine trellises are used for a very long period of time (20 + years) and must be able to withstand weather conditions and large crop weight. They are also economical to build and is relatively easy to maintain/repair. These are semi-permanent structures on the vineyards and can be arranged and built in several different styles.
WineFrog explains Trellis
There are many determents to consider when choosing a style of trellis. The type of wine, vine vigor, vine growth habit and root growth all attribute to the differing styles. The most common styles are High Cordon, Six-Cane Kniffen, Umbrella Kniffen, Geneva Double Curtain and Vertical Shoot systems. Each are suited for different kinds of vines, mostly dependent on vigor (the speed/quantity at which the vine grows) and growth habit (vertical, drooping, horizontal), and are mostly arranged in straight rows.
For commercial vineyards, which mostly use metal posts and wires, the cost of the trellis decreases as acreage increases. However, the spacing of the trellis can be adjusted to better suit the crop, landscape and location. The spacing is also specific to harvesting machines and other tools as well as irrigation systems. Low vigor vines do not need the wide spacing and larger trellising systems that high vigor vines do. Trellis systems in warmer climates and more sunlight have larger canopies and require larger trellises, whereas systems in colder regions with less sunlight and smaller canopies can have smaller trellises due to less growth. Trellis systems range from simple to complex and are used all over the world to grow grape vines.