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Wash outdoor cushions with a mild dish soap solution and a soft brush, treat mildew with either diluted bleach or borax depending on the fabric, rinse until the water runs clear, then dry them standing on edge in the sun for a day or more. The washing is the easy part. Almost every cushion that stays stained, smelly or moldy failed at drying, because the foam insert holds water long after the cover feels dry to the touch. Budget an afternoon of active work and a full day of drying, and do it on a hot, breezy, forecast-clear weekend.
First, find out what your fabric is
The cleaning method depends entirely on the fabric, and outdoor cushions come in three broad types.
| Fabric | How to identify it | Bleach safe? | Machine wash? |
|---|---|---|---|
| Solution-dyed acrylic (Sunbrella and similar) | Branded tag, soft canvas hand, fades very slowly | Yes, diluted per the maker | Usually yes, cold, air dry only |
| Solution-dyed olefin / polypropylene | Slick, slightly plasticky, common on value sets | Usually yes, diluted | Hand wash preferred |
| Coated polyester | Shiny water-repellent face, stiffer, most big-box cushions | No, it discolors | Hand wash only |
The difference matters because solution-dyed fabrics carry the color inside the fiber itself, so diluted bleach removes mildew without pulling the color out. Printed or piece-dyed polyester has color sitting on the surface, and bleach will take it with the stain. If you cannot tell, test whatever you plan to use on a hidden corner such as the underside of the cushion near a seam, wait 10 minutes, and check for lightening before you commit.
What you need
- A soft-bristle brush — a car wash brush or a nylon deck brush. Do not use a wire brush.
- Mild dish soap and a bucket of warm water.
- Borax or oxygen bleach powder for mildew on color-sensitive fabric.
- Household chlorine bleach for solution-dyed acrylic and olefin.
- A garden hose with a fan or shower nozzle. A quality nozzle makes rinsing far faster — see our hose nozzle picks if yours is worn out.
- A fabric protector spray if you want to restore water repellency afterward.
The step-by-step clean
- Brush the cushions dry, first. Take them off the furniture, stand them up, and brush both faces to knock off pollen, dust and cobwebs. Wetting a dusty cushion turns loose dirt into a slurry that soaks into the weave, so five minutes of dry brushing saves twenty minutes of scrubbing.
- Unzip and check the insert. If the covers come off, remove them and inspect the foam. Black speckling or a sour smell in the foam itself means you have to clean the insert too, not just the cover. Cushions that are sewn shut get cleaned as one unit.
- Mix the solution. General cleaning: a quarter cup of dish soap per gallon of warm water. Mildew on solution-dyed fabric: one cup of chlorine bleach plus a quarter cup of mild soap per gallon of water, which is the mix Sunbrella publishes in its own fabric care guidance. Mildew on color-sensitive fabric: half a cup of borax per gallon of warm water with a squirt of soap.
- Wet the cushion out completely, then apply. Hose the cushion down first so the solution spreads instead of concentrating in one spot and leaving a ring. Spray or sponge the solution over the whole panel, edge to edge, not just the stain.
- Let it dwell 15 minutes. This is where mildew gets killed. Scrubbing immediately does almost nothing; the dwell time does the work. Keep the surface damp — re-mist it if the sun is drying it out.
- Scrub with the soft brush. Work in overlapping circles with light pressure. Heavy pressure on a coated polyester face abrades the water-repellent finish and leaves a permanently darker, wetter-looking patch.
- Rinse until the water runs clear. Not until it looks clean — until it runs clear. Leftover soap in the fibers is sticky and attracts dirt within days, which is the usual reason a freshly cleaned cushion looks grubby again in a week. Rinse both sides, then squeeze a corner and check the water coming out.
- Flush the insert if it is contaminated. Stand the bare foam in a driveway and hose it, pressing it down with your foot and letting it re-expand to pump water through. Repeat until the squeezed-out water is clear.
- Squeeze out as much water as you physically can. Lay the insert on a clean slab, put a board on top, and stand on it. Roll it and press it. Every ounce you remove mechanically is an hour you save in drying.
- Dry standing on edge, in the sun. Lean the cushions vertically against a wall or rail so both faces get air and gravity pulls the water down and out. Flat on a table is the classic mistake — the underside stays wet all day. Expect 12 to 24 hours in warm, dry conditions, and 48 hours or more in humid weather.
- Reassemble only when the foam is bone dry. Press the middle of the insert hard with your palm and feel for cold dampness. A cover zipped over a still-damp insert grows mildew within a week, and you will be doing this again.
Specific stains and what actually lifts them
| Stain | Treatment | Notes |
|---|---|---|
| Mildew and black speckling | Diluted bleach or borax, 15-minute dwell | Fix the drying or it returns |
| Tree sap and pollen | Rubbing alcohol on a cloth, then soap and water | Blot, do not grind it in |
| Sunscreen and body oil | Degreasing dish soap, warm water, repeat | The orange avobenzone stains often need two passes |
| Red wine and berry juice | Cold water flush immediately, then oxygen bleach soak | Never use hot water first, it sets the pigment |
| Bird droppings | Scrape dry, then soap and water, then disinfect | Wear gloves; droppings carry pathogens |
| Grease and grill splatter | Cornstarch to absorb, brush off, then degreaser | Move seating clear of the grill next time |
Mistakes that ruin cushions
- Machine drying a fabric that says air dry. Heat shrinks the cover just enough that it will not go back over the foam, and there is no undoing it.
- Fabric softener. It leaves a residue that traps dirt and destroys water repellency. Skip it entirely on outdoor fabric.
- Pressure washing at full power. It forces water deep into the foam and blows out stitching. If you must, stay under 500 PSI with a 40-degree tip.
- Drying flat. The bottom face never dries and the mildew grows back from the inside.
- Storing cushions in a sealed bin while faintly damp. This is how a cushion set gets written off over a single winter.
Reproofing and keeping them clean
Once the cushions are fully dry, a fabric guard spray restores the water-repellent finish that washing strips off. Apply it outdoors in thin, even coats on a dry, warm day, and let it cure per the label — usually 24 hours before the cushions get rained on. Reproofing is worth doing annually on coated polyester and every two or three years on acrylic.
After that, the maintenance is boring but effective: bring cushions in or under cover when heavy rain is forecast, store them somewhere ventilated rather than sealed, and stand them on edge overnight after a wet day. If your cushions are past saving, replacement sets and covers are covered in our patio furniture set picks, and the same cleaning discipline applies to shade fabric — see how to clean a patio umbrella.
A note on bleach and safety
Never mix bleach with ammonia or with any acid-based cleaner such as vinegar or a bathroom descaler — the combination releases toxic chlorine gas. Work outdoors, wear gloves and eye protection, and keep bleach solution off the lawn and off plantings, since it will kill grass and shrubs at the runoff point. Rinse the surrounding patio afterward. If your cushions have a manufacturer care tag, that tag outranks any general advice here.
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