Freestanding support for climbing vines
How solidly you build a trellis depends on the size and longevity of the vine it is to support. For a heavy wisteria, grape, or rambler rose, make a frame of 2 x 4’s. Reinforce the joints with galvanized-steel corner braces, and nail on a latticework of 1 x 2’s or interwoven strips of cinch lath.
Fora lighter clematis or honeysuckle, use 2 x 2’s and 1/2-inch lath. Tomatoes, cucumbers, and such annual vines as morning glories can be supported for a season on a frame of 1 x 2’s covered by lath or wire mesh; or buy ready-made plastic or wire supports from your hardware or garden supply store.
For a long-lasting trellis, at least 2 feet of the upright posts should be sunk below the soil surface. Use pressure-treated lumber or a resistant wood such as redwood, cedar, or cypress for the posts. If you use a resistant wood for aboveground parts, it can be left unpainted. Apply at least two coats of outdoor paint to other kinds of wood; let it dry before planting.
The face of a trellis built against a wall must be at least 4 inches from the wall to allow adequate air circulation. Hinge it at the base for convenience in maintenance and repair.