A garden trellis can either be installed into the ground or a pot. For adequate support and stability. a freestanding trellis should be driven at least 2 feet into the ground. “Another option is installing some sort of rebar post or a T-post in the ground before adhering your trellis to it,” says McKenzy Winkler, a master gardener and herb farmer. “Using metal over wood ensures that the base won't rot or crumble under the weight of the plant.” A wall-mounted trellis is affixed with brackets to keep it securely in place.