How do you construct a grapevine trellis?
Constructing a grape trellis is similar to constructing a farm fence. A trellis basically consists of one, two, or three tightly stretched wires secured to firmly set posts. It must be substantial enough to carry the weight of the vines plus a heavy crop during high winds. End posts serve as anchor points as well as wire supports. They are generally 8 feet long with a 4-inch diameter. Set end posts approximately 2 feet deep in the soil for very short trellises. Longer trellis lengths will require longer end posts that are set 3 to 4 feet deep. They may be braced in several ways. A common method is to set an extra post a few feet from the end post. A heavy piece of wood or another post makes a good brace between the two end posts. Line posts also are approximately 8 feet long, but with a 3-inch diameter. Set line posts approximately 2 feet into the ground and space approximately 24 feet apart within the row.
Use galvanized wire in trellis construction. It is durable and does not cause serious chafing of young vines. Commonly used wire sizes include numbers 9, 10, and 11. Wires can be secured to end posts in various ways. A common method involves winding the wire around one end post once or twice and then twisting the end several times around the wire as it is stretched to the next post. It is recommended that special devices that simplify tightening of the wires be attached at one end of the trellis to allow for wire tightening. Fasten wires to the line posts loosely with ordinary staples to allow tightening. Determine wire placement by the training system followed. For example, in the single curtain cordon system, the single wire is about 6 feet high, and in the Geneva Double curtain system three wires are set horizontally at a height of six feet.