Trellises allow you to take advantage of the vertical space in your garden. They give life and color to the sides of buildings and fences, or they can stand alone as a tall focal point in a center oasis. Stabilizing the bottom by installing it deep enough in the ground is key to keeping a trellis standing for years. Note that you should always call 811 to have utility lines marked before digging in your yard.
Fan-shaped trellises are typically lightweight and are designed to hold plants that don't get very heavy, such as clematis (Clematis), grown in U.S. Department of Agriculture plant hardiness zones 5 through 9. Fan trellises are ideal next to a building or fence, and adding stability after burying the base is as simple as screwing them into the side of the structure. To keep the bottom secure, dig about 2 feet deep. The trench should be slightly longer than the small base of the fan trellis. Add about 6 inches of gravel to the bottom of the trench for drainage, which gives you about 18 inches of depth for the trellis base. (Ref. 3)
When It's Square
Some trellises come in panels that are either square or rectangular. Instead of having to dig a trench to bury the base, choose these trellises with grounding posts attached. Use a post-hole digger to dig holes 2 feet deep, measuring carefully so you know exactly where to place the holes. This saves you time by allowing you to bury only the posts, not the entire base. If your soil is dense, dig an extra few inches, between 4 and 6 inches, and fill that space with gravel to allow for drainage. When you backfill the holes with dirt, tamp it down every few inches to create a tight hold. (Ref. 1 and 2) These trellises often stand alone in your garden and can hold heavier plants, including vegetables such as summer squash (Cucurbita pepo). The heavier your trellis and plants are, the deeper you should bury your trellis.
Many trellises don't have to be buried in the ground. Instead, use large containers to hold the trellis in place and give your plants a safe place to grow. Containers work best with light trellises, such as the fan-shaped ones, and should be at least 2 feet deep -- even little kids can get involved with digging out space for a trellis in a container. A couple of inches of gravel at the bottom helps with drainage. Using containers allows you to move the trellis with relative ease when you change your mind or the garden's layout. (Ref. 3)
No Digging Required
You don't always need to bury the trellis base. When using a lightweight trellis, either square or fan-shaped, you can attach it to a building or fence at your desired height. It can be even with the ground or mounted above your existing bushes, for example. It's best to install a trellis into wall studs or fence supports if possible, using galvanized screws. Masonry screws allow you to install onto stucco or brick as well. (Ref. 4)