Mold on outdoor furniture is mostly a moisture problem, and in a humid city summer it gets worse because rain, shade, pollution, and still air all help spores settle and grow. I’d start by keeping everything as dry and ventilated as possible. Don’t push furniture tight against walls or railings; leave gaps so air can move around it. If you have a balcony, avoid clustering chairs and tables in the dampest corner. Elevate pieces slightly off the floor with small feet or pads so water doesn’t sit underneath.
Choose breathable covers instead of plastic tarps. Plastic can trap condensation and create a mini greenhouse, which is exactly what mold likes. If rain is coming, cover cushions or take them inside, but never put them away damp. Cushions should be brought in overnight or during wet spells, and they need to dry completely in sun and airflow before storage. A waterproof liner can help, but make sure water can’t get trapped between layers.
Clean furniture more often than you might think, especially in a city. Dust, pollen, and pollution form a film that feeds mold. Wipe frames with mild soapy water, rinse, and dry with a cloth. For early mold spots, a diluted white vinegar solution works well on many surfaces; test a hidden area first. Avoid harsh bleach on wood, fabric, or painted metal unless the manufacturer recommends it.
Material choice matters. Powder-coated aluminum, quality metal, teak, and high-density polyethylene tend to handle humid summers better than porous materials or cheap untreated wood. Seal wood according to the maker’s instructions, and use mold-resistant outdoor fabric for cushions where possible. Avoid stacking wet chairs or storing damp cushions in a closed box. If you have a covered area, a small fan or good cross-ventilation helps a lot. Check weekly during the wettest months, scrub spots early, and let everything dry fully before covering or storing it. The goal isn’t to fight mold after it appears; it’s to deny it the damp, dirty, still conditions it needs.