Construct your trellis at planting, when soil is soft and tilled. Dig 2-foot-deep holes for the poles of your trellis, 1 foot behind each row of grapes. Set the holes at every 20 feet in the row, or at the ends of shorter rows. Give each row of grapevines its own set of poles for trellising and training.
Put poles into the holes and fill around them with soil. Pack the soil firmly around the base of each pole to secure it.
Wrap a length of 9- to 11-gauge wire around the top of the first pole in the first row. Run the wire to the next pole in the row, wrap once around the top of the pole, and move to the next. Secure the wire on the last pole in the row and cut off the end.
Repeat this process with one to two more wire tiers, with each tier 2 feet below the last. These tiers provide support for growing and training. The bottom tier must sit at least 2 feet above the soil.
Repeat this process with every row throughout the vineyard. Grapes don't produce fruit without adequate support and space.