That's an excellent and very practical question! The need for a special foundation largely depends on three key factors: the bench's material and weight, your local ground conditions, and your desired level of permanence and stability.
For heavy benches made of stone, cast iron, or thick hardwood, a proper foundation is highly recommended. Pouring simple concrete footings below the frost line prevents shifting during freeze-thaw cycles. For most standard wooden or metal benches on stable, level ground like a compacted patio or deck, you might not need a full foundation. However, we always advise some form of anchoring.
A great middle-ground solution is using a gravel base. Digging a shallow area, filling it with crushed gravel, and compacting it provides excellent drainage and prevents rot and sinking. For ultimate security on lawns or soil, consider driving galvanized ground spikes or anchors through the bench legs into the earth.
In short, while not always mandatory, a proper base—whether concrete, gravel, or anchors—dramatically extends your bench's lifespan, ensures safety, and keeps it beautifully level for years to come. Always check the manufacturer's guidelines for specific recommendations.