That's an excellent question, and the answer is: it depends. Most standard outdoor benches are designed for straightforward installation, but the need for a special foundation largely hinges on the bench's material, weight, design, and the specific ground conditions where you plan to place it.
For lightweight benches made from materials like recycled plastic, aluminum, or some types of cedar, you often don't need a permanent foundation. These can typically be placed directly on level, stable ground, such as a well-compacted lawn, patio pavers, or a deck. The key is ensuring the ground is firm and even to prevent wobbling.
However, for heavy benches—like those made from solid stone, thick cast iron, or large timber—a proper foundation is highly recommended. A simple concrete pad or a bed of compacted gravel provides a stable, level base. This prevents the bench from sinking into soft soil over time, which can cause instability and potential damage. Benches with a cantilevered design or those in high-wind areas also benefit significantly from being secured. For permanent installation, you can set the bench's legs into wet concrete or use concrete footings with anchor bolts.
Ultimately, while not always mandatory, taking the time to prepare a proper foundation will dramatically extend the life of your bench, enhance its safety, and ensure it remains a steady and welcoming spot in your garden for years to come. Always refer to the manufacturer's specific installation guidelines for the best results.