Use the post digger to create four evenly spaced out holes in the ground, in the shape of a box. An average size of a grape arbor is about four feet long and five feet wide. The holes need to be about 2 feet deep. Make the diameter of the holes slightly smaller than the width of your wooden posts to ensure the most tight fit.
Pour the gravel into the bottom of the post holes, dividing it evenly.
Secure each post into the arbor holes. Start by pushing firmly down into the hole, then twist it in clockwise if there is a lot of resistance. Repeat this with all four posts.
Drill three holes into the side of each wooden post. Space one hole 3 inches down, one hole 5 inches down, and one hole 7 inches down from the top. The holes should facing the post that is closest to the left. Insert an eye screws into each hole.
Firmly secure the edge of the wire outside one of the posts bottom row of eyes with hardware staples (specific to the type of wire you can find at your local hardware store). Pull the wire taut through the first row of eyes on all four wooden posts, making a wire box shape. At the last post, wrap it firmly around the top and secure it with a staple before cutting.
Repeat this wire procedure with the second and third row of eye screws, which creates the upper part of the arbor. This provides a place for the grapes to eventually grow upwards and over.