Start by figuring out what the furniture is made of, because that changes how aggressive you can be. City grime is usually a mix of dust, exhaust soot, pollen, oily film, tree sap, and the occasional bird dropping, so a quick wipe often just pushes it around. I like to begin with a dry soft brush or microfiber cloth to lift loose dirt, then wash with warm water and a few drops of mild dish soap. Use a soft sponge or brush, work in small sections, and rinse thoroughly so you do not leave a soapy film that attracts more dirt.
For metal furniture, wipe down frames and legs, rinse well, and dry immediately to reduce rust and water spots. Check for chips in the paint or powder coating and touch them up when you can. For wood, use as little water as possible, scrub gently with soapy water, rinse quickly, and dry completely; then re-oil or seal it according to the manufacturer’s advice. For plastic, resin, and wicker, a soft brush and mild soapy water usually do the job, but rinse out crevices where grime collects. For fabric cushions, check the care label first, use a mild detergent and soft brush, rinse well, and let them air dry fully in a ventilated spot.
Bird droppings and sticky sap need a little patience. Wet the area with soapy water, let it soften, then wipe with a disposable cloth or paper towel; avoid scraping dry droppings, which can scratch the surface. For tough sap, test a little rubbing alcohol on an hidden spot first. Avoid harsh bleach, abrasive pads, and high-pressure washing on joints, wicker, or painted finishes. Once everything is clean, dry it thoroughly, and plan a quick wipe-down every few weeks so city grime does not get a chance to bake on.