Locate wall studs with a stud finder or look for nail heads showing through the siding. Studs in walls are set on four-foot centers, or four feet apart.
Place the trellis against the wall and make a mark with a carpenters pencil on the wall where each corner of the trellis will rest. Assistance may be needed with this step. The mark should be directly in the center of the stud located behind the siding. Mark each corner of the trellis where it matches the marks on the wall. These are the spots where screws are drilled to mount the trellis to the wall.
Hold the trellis against the wall in the desired location. Drill a 1/4-inch-diameter hole through the trellis frame and the siding into the stud. Do not drill more than three quarters of the way through the stud.
Position a 1 1/8-inch-long copper pipe coupling at the mark in the top of the first stud, between the trellis and the wall. Insert a 4-inch -long by 1/4-inch-diameter stainless steel wood screw through the trellis, the copper pipe coupling and into the stud.
Repeat the same process at each of the remaining three marks to secure the trellis to the wall.