Trellises may be freestanding and portable, or attached directly to your house, but one thing all trellises should be is sturdy. Growing plants exert considerable force on trellises, and if this is not met by equal resistance your prized peas may wind up on the ground. Always start with new, strong material when building trellises, and use naturally rot resistant woods like cedar or redwood to prevent rotting. This tent trellis design, adapted from the book "Build It Better Yourself," will support most vines handily.
Drill quarter inch holes for stove bolts (centered), 12 inches from one end of each of the 8-foot-long cedar or redwood pieces.
Set four of the 8-foot pieces on level ground---parallel with one another and with the undrilled sides facing up. Draw a line across all four at 13 inches below the end (on the same end you drilled previously).
Lay all three 6-foot pieces together parallel to one another (with ends squared); measure and mark them all from the same end at these points---6 inches, 26 inches, 46 inches, and 66 inches.
Take one 6-foot piece (top cross piece) and turn it so that it lies perpendicular across the four 8-foot pieces at the line 13 inches from the drilled ends. Adjust so that the 8-foot pieces lie centered below the marked points on the 6-foot cross piece (keeping the 6-foot piece straight along the line 13 inches from the end).
Nail the 6-foot top cross piece across the 8-foot upright pieces.
Lay another of the 6-foot cross pieces along the bottom of the 8-foot uprights---spaced exactly as the top cross piece---and nail in place with brads as before.
Position the diagonal brace so that it lies across the completed framework from an upper to lower corner. Nail each upright where it crosses.
Set the completed frame aside temporarily.
Lay out the remaining 8-foot pieces. Nail the remaining 6-foot cross piece to the bottoms as in Step 6 (centering each 8-foot piece below marks made on the cross piece).
Bring back the first frame (previously set aside) and set it down flat next to the other frame so that the ends with drilled holes lie adjacent to one another.
Position the uprights of each frame so that they are parallel and touching. Slide the two frames together until the drilled holes in each upright align with one another in pairs.
Place one stove bolt through each pair of drilled holes (use the washer against the wood on the opposite side). Screw them on, but do not tighten the nuts at this point.
Stand the joined frames upright over a garden bed to create a trellis "tent" with bottom cross pieces about 2 feet apart.
Drive tent stakes into the ground outside each corner and attach the ends to the stakes with wire or heavy twine to hold the framework in place.