An obelisk trellis is a tall and thinly tapered four-sided plant frame that is used in the garden not only to support climbing plants but also to provide a feature or accent to the landscape. The obelisk shape lets flowering shrubs rise high so that their blooms can be seen from all areas of the garden. Obelisk trellises are available already constructed, especially those made of metal rods; but for the do-it-yourselfer, building an obelisk plant frame from pieces of wood can be a worthwhile weekend project.
Design your obelisk trellis. Use paper and pen to draft the design and dimensions of your plant frame. Take note of the location in your garden, the height and width of the frame, and the tools and materials you will need to complete the project.
Cut four 15 cm (6 inch) wood strips to form the top rail of the obelisk.
Lay two posts on the ground and use screws to attach a 15 cm (6 inch) wood strip to connect the tops together. Spread the legs apart and mark the points where the horizontal wood strips will be attached. Depending on the height of the obelisk, you can have three, four or five horizontal pieces in increasing lengths from the top to the bottom of the obelisk.
Cut wood strips to form the horizontal pieces corresponding to the marked locations on the posts. Since the obelisk will have four identical sides, cut sets of four wood strips to account for the four sides of the trellis.
Attach the wood strips to the posts with screws. Alternatively, the horizontal pieces can be attached with wires, binds or nylon cords.
Construct the second frame in the same manner as the first.
Raise the two frames upright and attach the 15 cm (6 inch) wood strips to the tops to form the four-sided obelisk. Attach the remaining wood strips to their designated points.
Place the completed obelisk trellis at its intended location. If necessary, sink the legs of the trellis into the ground for stability.
When attaching the horizontal rails, start with the bottom piece to hold the legs in place. You will need a helping hand to hold the first two trellis frames while the top and bottom horizontal pieces are screwed to the posts. For a cottage garden feel, use dried twigs from tree prunings to construct the trellis. Consider using bamboo canes, metal rods or treated lumber as materials for the trellis. Painting the trellis will make it more attractive and last longer while exposed to the elements.