How to Remove Mould and Mildew from Outdoor Furniture

Mould or mildew? Check what you are dealing with

People use the two words interchangeably, but what you can see on the surface tells you how hard you will need to work.

• Mildew is flat and powdery, usually white, light grey or yellowish, and sits on the surface. It has a faint musty smell and generally wipes off with mild soap and water.
• Mould is fuzzy or slimy, usually black, dark green or blue, and grows into porous material such as timber, cushion fabric, foam and the gaps in a weave. It needs more work and sometimes cannot be fully removed.

Caught early, either is a quick clean. Patches that have stained the material, smell strongly or have spread are established, so expect to repeat the process.

This guide covers outdoor settings. For an indoor fabric sofa or armchair, follow our separate guide on how to remove mould from fabric furniture, because indoor upholstery needs a gentler, drier method.

Before you start: safety and the gentle-first rule

• Protect yourself. Wear rubber or nitrile gloves, eye protection and a mask. Scrubbing mould releases spores, so work outside, not in a garage, and brush off loose growth before you wet anything.
• Never mix bleach with ammonia. Combining them releases a toxic gas. Some glass and multipurpose sprays contain ammonia, so if you have already used another cleaner, rinse the surface with water first.
• Protect plants and pets. Diluted bleach and vinegar can damage plants. Move the furniture onto pavers or a driveway, or lay a drop sheet underneath, and keep pets away until everything is rinsed and dry.
• Patch test first. Try any cleaner on a hidden spot, such as the underside of a cushion or the back of a leg, and check the result once it is dry.
• Start gentle and step up. Mild soap first, then vinegar, then diluted bleach only where the material allows it. Going straight to the strongest option risks fading fabric or stripping timber when you did not need to.

How to remove mould from outdoor cushions

Cushions are where most outdoor mould starts, because fabric and foam hold moisture long after the frame has dried.

1. Take the cushions off and work in the sun. Brush off loose growth with a soft brush.
2. Read the care label. Some outdoor fabrics tolerate a diluted bleach solution and many do not. The care instructions on our own outdoor pieces say to spot clean with a mild soap solution, so that is where to start.
3. Wash the marks. Work mild soapy water into the fabric with a soft brush or cloth. If you prefer a purpose-made fabric cleaner, the Guardsman Fabric Care Kit is made for fabric upholstery: a Level 1 cleaner for everyday marks, a Level 2 deep cleaner for stubborn ones, a deodoriser and soft applicator cloths. Test it on a hidden area first.
4. Rinse thoroughly until the water runs clear, because soap left in the fabric attracts dirt.
5. Dry completely. Stand cushions on their edge in sun and breeze, turning them so both faces dry. Do not put them back, stack them or cover them while the foam is still damp.
6. Protect the clean fabric. Once the fabric is clean and completely dry, Guardsman Weather Defence Fabric Protector adds an invisible, breathable barrier that makes water bead off rather than soak in and helps resist mould and mildew. Spray two light coats and reapply each season or after heavy rain and cleaning.

Fabric type matters. The Portals 3 Seater Outdoor Lounge uses 100% Olefin cushions at 190gr, a synthetic fibre chosen for its resistance to UV, moisture and mildew. The Hydra 2 Seater Outdoor Sofa has 175gsm outdoor polyester cushions, and the Panama 4 Piece Outdoor Sofa Set uses fire-retardant polyester. For all of them, spot cleaning with mild soap and drying fully is the place to start. Our outdoor fabric guide compares the fabrics in more detail.

If the mould is inside the foam, cleaning the cover will not fix it. If spots keep coming back a few weeks after a thorough clean, or the cushion smells musty once it is dry, the foam is the source and replacing it is the realistic answer.

Aluminium and metal frames

Aluminium does not grow mould itself, but mildew grows on the dirt, pollen and leaf litter that collect in joints, under arms and along the underside of a powder-coated frame.

• Wash with mild soapy water and a soft brush or cloth, working into the joints and corners.
• Rinse and dry with a towel so water does not sit in recesses.
• Avoid abrasive pads, steel wool, scouring cream and melamine sponges, which can scratch or dull the powder coat.

The Panama set is a good example: its charcoal aluminium frame and slatted aluminium coffee table only need a damp cloth, so any mildew on them is sitting on debris that a wash removes.

Teak and eucalyptus timber

Timber is porous, so mould can sit in the grain. Our lounges with timber details include the Portals Outdoor Corner Lounge, which has solid teak side panels at both ends, and the Hydra 2 Seater, which has a slatted eucalyptus side table built into one end.

• Brush off loose growth, then scrub with mild soapy water and a soft brush, always along the grain, not across it.
• For marks that remain, try 50/50 white vinegar, leave it for a few minutes, scrub along the grain and rinse well.
• Let the timber dry completely. If you oil it to keep the warm colour, the product pages suggest a teak or outdoor hardwood oil, and the timber must be clean and dry first. Oiling over mould seals it in.
• Silver-grey weathering is not mould. Untreated teak and eucalyptus naturally turn silver-grey over time; mould shows as dark spots or patches.

For timber that has gone grey, rough or blotchy, our step-by-step guide to restoring weathered teak covers cleaning back and re-oiling.

Synthetic wicker

Synthetic wicker strands are plastic, so the mould is growing on debris caught in the weave rather than in the strands themselves. The challenge is getting into the gaps.

• Hose the piece on a gentle setting to flush out leaves and dust.
• Work a soft brush dipped in mild soapy water along each row of the weave, then rinse.
• Do not use a pressure washer or a stiff brush, which can damage strands and push water into the frame.
• Dry it in the sun before you put cushions back or cover it.

Natural rattan is a different story: the porous cane holds moisture and spores, and deep mould in real rattan is often permanent. Our guide to synthetic wicker vs natural rattan explains why.

How to stop mould coming back

If mould returns a few weeks after a good clean, the cleaning worked; something is keeping the furniture damp. In humid summers, especially after a run of storms, mould can return quickly, so these habits matter more than any cleaner.

• Clear debris quickly. Leaves, blossoms, pollen and bird droppings are what mould feeds on. Brush and rinse them off soon after a storm, not at the end of the season.
• Let it breathe. Furniture pushed against a wall, tucked into a corner or surrounded by dense plants stays damp longest. Leave a gap for air to move.
• Keep it out of puddles. If water pools where the furniture sits, move the setting or fix the drainage.
• Do not leave covers on for weeks. A cover that stays on through humid weather traps moisture and whatever was on the furniture underneath it. Take covers off in dry weather and never cover anything damp.
• Bring cushions in. Store cushions indoors or somewhere dry when the setting will not be used for a while, and dry them fully after rain before you put them away.
• Re-treat fabric. A water-repellent fabric protector stops rain soaking in, so cushions dry faster. Reapply it each season and after a deep clean.

For a season-by-season routine, use our seasonal outdoor furniture maintenance checklist, and before storm season read how to protect outdoor furniture from storms. You will find care products in our furniture care range and weather-ready settings in outdoor lounges. We have five showrooms; ask which store has the piece you are interested in on display, and our team can talk you through its materials.

Mould and mildew FAQs

• Can I use bleach to remove mould from outdoor cushions?

  Only if the cushion's care label allows it. Some outdoor fabrics tolerate a diluted bleach solution, but many polyester fabrics can lose colour. Start with mild soapy water and a soft brush, patch test anything stronger on a hidden spot, rinse thoroughly and never mix bleach with ammonia-based cleaners.

• Does vinegar kill mould on outdoor furniture?

  White vinegar mixed 50/50 with water is a useful next step when mild soap has not shifted mildew. Apply it, leave it for a few minutes, scrub with a soft brush and rinse well. Keep it off natural stone and unsealed grout under the furniture.

• How do I get mould out of the foam inside outdoor cushions?

  Usually you cannot. Cleaning the cover only treats the surface. If spots return a few weeks after a thorough clean, or the cushion smells musty once it is fully dry, the foam is the source and replacing it is the realistic answer.

• Should I pressure wash mouldy outdoor furniture?

  No. A pressure washer can damage wicker strands, fabric and timber grain and push water into frames and foam. Use a garden hose on a gentle setting, a soft brush and mild soapy water, then let everything dry fully in the sun and breeze.