I have two trellises, each about 8 feet high. I have one on either side of a walkway leading into my backyard. I ran a few strings from the top of one trellis to the other, and planted hops under one of them. The hops grow up their own trellis, and then across the strings to the top of the other one. The hops have no problem growing laterally along the strings, and the yield along that point is tremendous. So it does not need to be entirely vertical. Also, it creates a gorgeous canopy over the walkway, and they are low enough to harvest without a ladder. After planting two rhizomes a couple years ago, I got almost 2 pounds of hops this past year.