New homeowners desiring a more attractive backyard living space for their families often turn to trellises. They provide a shot of beauty and timeless elegance to their outdoor backyard haven. Whether you want a trellis to serve as a privacy screen or simply a convenient clambering location for your favorite climbing vines, cedar provides an ideal wood choice due to its decay-resistant qualities, according to Jim Long, author of "Making Bentwood Trellises, Arbors, Gates and Fences." Use 4-inch-by-4-inch posts and 1-inch-by-2-inch crosspieces as the main components to create a solid wood trellis that will last in your backyard for years. Measuring 4 feet wide by 7 feet tall, this trellis weathers to a soft gray color that blends in well with most landscape styles.
Hammer two wooden stakes into the ground 4 feet apart to mark the post locations for your backyard trellis. Use a post hole digger to excavate the post holes to a depth of 2 feet.
Insert the end of one post into one of the holes. Check with a level to ensure that the post is straight, then pound dirt in around the post with a tamping rod to secure the post solidly into the ground. Repeat this process for the other trellis post, making sure the outside edge of the second post is exactly 4 feet from the outside edge of the first cedar post.
Turn one of the 2-inch-by-4-inch boards perpendicular to the posts. Locate the board approximately 6 inches from the ground and make sure the ends of the board are flush with the outside edges of the two posts. Secure the 4-inch side of the board to the cedar posts with 1 ½-inch galvanized nails. Repeat this entire process with the second 2-by-4-inch board, locating it flush with the top edges of the two poles. This should create a rectangular framework for your trellis.
Position the first horizontal 1-inch-by-2-inch support board 3 inches above the bottom 2-inch-by-4-inch board. Make sure the horizontal support board is parallel to the 2-inch-by-4-inch board before you nail it in place to the posts. Repeat this process for each horizontal support board, locating each one 3 inches above the previous one. This should create a ladder-like set of support boards.
Move to the other side of the trellis support frame. Position one of the 1-inch-by-2-inch vertical support boards parallel to the posts, locating it approximately 4 inches from one of the posts. Make sure its ends are flush with the edges of the two horizontal 2-inch-by-4-inch supports before you secure it to them with nails. Repeat this process with the rest of the vertical support boards, locating them approximately 4 inches apart.