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If you want to grow grapes on an arbor, you will need to follow the same transplanting and first year steps you would follow for standard grape vines grown on a trellis or fence.  Grow one grapevine per post. If you have a two post arbor, grow two vines, training each one on a separate post. Grow four vines if you have four posts, or six vines if you have six posts.  Allow the main trunk to grow to the top of your post during the first year. Tie or secure it to the post as it grows. During the first winter, cut down the main trunk to a bud just above the top of the post. Allow any lateral side canes to grow on top of the arbor. Lateral side canes growing below the top of the arbor should be pruned down to trunk level. Any cane that produced fruit during the previous growing season should be cut off completely.  While these old canes can remain on the vine without causing disease or damage, keeping them on the vine will cause dense shade to form with little to no fruit. You should also remove any weak, thin, or diseased canes, even if they have not yet produced fruit. Select one to three healthy, used canes from each vine and trim them down to two or three buds instead of cutting them off completely. Canes that developed during the previous growing season should be kept, but you will need to cut them back to only five or six buds.  Ideally, the canes on your arbor should be spaced 2 to 3 feet (60 to 91 cm) apart by the time you finish pruning. After your first two or three years, you should have a well-established set of vines that can fill in the arbor top by the end of your growing season without becoming hopelessly tangled.
Follow the same initial steps. Allow branches to grow along the top. Remove used canes. Leave several renewal canes. Cut back the remaining canes.