I’ve had this happen on a small city patio, and the fix is usually a mix of prevention and quick cleanup. Rust stains on concrete come from water sitting against metal furniture legs, especially where paint has chipped or welds collect moisture. Start by lifting the furniture off the concrete. Rubber cups or plastic glides on every leg are cheap and make a big difference, but check them often because grit trapped underneath can scratch the surface. If the legs are already rusty, sand off the loose rust, wipe the area clean, and touch up the paint with a rust-inhibiting spray or enamel. For extra protection, run a small outdoor rug or patio mat under the seating area and keep it dry; just avoid trapping water underneath.
When you buy or replace urban outdoor furniture, look for rust-resistant options such as powder-coated aluminum, stainless steel, or good-quality resin. Wrought iron looks great but needs regular paint maintenance. Also, tilt chairs and tables slightly or store cushions away so water doesn’t pool on the frame. In rainy or humid weather, a breathable cover helps, but don’t wrap metal furniture tightly in plastic—that traps condensation.
For existing stains, act fast. Scrub with a stiff brush and a paste of baking soda and water, or try white vinegar on lighter marks. For stubborn rust, use an oxalic-acid rust remover made for concrete, following the label carefully, and rinse well. Seal the patio if stains keep coming back, and reapply sealer as recommended. The goal is to keep metal legs dry, protected, and slightly elevated—small habits save a lot of scrubbing.