Pea plants consist of shorter varieties, which typically grow no more than about 2 feet, and--less commonly--taller varieties, which usually grow up to about 6 feet in height. Regardless of what pea species you ultimately decide to grow, a trellis provides a support structure that makes harvesting less troublesome, especially for gardeners who have back problems. Go for a long, low trellis, which you can build in a single afternoon using an affordably priced livestock panel. Patricia Lanza, author of "Lasagna Gardening for Small Spaces," suggests that you plant a row of peas on either side of your trellis, locating the rows about 6 inches apart, to make maximum use of the trellis as a support for your peas.
Purchase a single livestock panel and three steel T-posts for every 16 feet of pea plant rows that you want your trellis to support. For example, if you plan to have a 32-foot-long double row of peas, get two livestock panels and six steel T-posts. Look for the 16-foot-long livestock panels, which consist of a framework of stiff, intersecting horizontal and vertical steel rods, at your local farm and agriculture supply center. Opt for shorter "hog" panels if you have the shorter pea plants; go with taller "cattle" panels if you plan to raise some of the taller species of peas.
Visualize an imaginary line straight down the center of your double row of pea plants. Sink one of the steel T-posts into the ground, locating it at one end of the imaginary line. Drive the post 9 to 12 inches into the ground with a handheld post driver. Measure 7 ½ feet straight down your imaginary line, and sink a second post 9 to 12 inches into the ground. Repeat this process to drive one more steel T-post into the ground 7 ½ feet from the second post.
Lift the livestock panel with the help of a friend, and line it up with the three T-posts. Let 6 inches of the panel jut out from the two end posts. Wire the livestock panel to the T-posts with 6-inch strips of 14-gauge galvanized wire. Wrap one strip of wire around the T-post and the bottom horizontal steel rod in the cattle panel; wrap a second strip of wire around the T-post and the top horizontal rod in the panel. Space additional wires every 9 to 12 inches along the height of the panel. Repeat this entire process for each pea trellis that you need.