Agriculture Reference
In-Depth Information
The Vertical Shoot Positioning (VSP) System
Each row of a VSP trellis consists of four rows of wire tightly strung between support-
ing posts. Heavy end posts provide the main support for the wires; lighter mid-posts serve
as wire guides. The end posts are typically wood, but unless they are chemically treated,
they must be a naturally rot-resistant wood such as cedar, juniper, or redwood. An altern-
ative—which may be a requirement for organic certification—is to use metal end posts.
There are a number of different types of metal posts. The most important consideration is
whether they have sufficient tensile strength for the length of your rows.
The wire closest to the ground supports a drip irrigation tube at about 14 inches.
Above this is the fruiting wire, a single wire where the grapes will develop. Above the fruit-
ing wire are two double sets of positioning, or training, wires at approximately 4 and 5 feet.
Eventually, when the vines are mature, the trellis must carry the weight of all the vines, ir-
rigation lines, and (hopefully) many bunches of grapes. That is why the trellis system must
be sturdy, well-designed, and properly installed.
