At the end of this task, the fabric is clean, fully dry and stored in a breathable cover in a dry space. Drying time depends on the weather, and none of the sources give a figure in hours. Before you start, know one rule: if any part of the fabric is damp, do not store it.

What you need

  • Soft-bristle brush

    Do not use a pressure washer.

  • Bucket and garden hose

    Use cold or lukewarm water, as the fabric type requires.

  • Mild dishwashing liquid or neutral liquid detergent

    The amount depends on fabric type. See the table in the steps.

  • Mildew treatment for your fabric type

    Bleach is for acrylic only. Use hydrogen peroxide or diluted white vinegar for polyester.

  • Gloves and eye protection

    Wear these for any bleach or mildew remover.

  • Breathable cotton or fabric storage bags

    Do not use sealed plastic bins or plastic bags.

  • A shelf, rack or pallet

    This keeps the fabric off the floor.

  • Silica gel packs (optional)

    These absorb excess humidity during storage.

The steps

Match the wash to the fiber. The figures below come from Sunbrella's cleaning guide and the Trivantage awning guide. Mildew risk by fabric comes from Canvas Etc.

Fabric Wash solution Mildew treatment Mildew risk in storage
Solution-dyed acrylic (Sunbrella, Dickson) 1/4 cup (about 60 ml) dish liquid per 1 gallon (3.8 l) water 1/4 cup dish liquid plus 1 cup (about 240 ml) bleach per 1 gallon water Low. Mildew inhibitors are often added in dyeing.
Polyester 1 tbsp dish soap per 2 cups cold water Hydrogen peroxide or diluted white vinegar. No undiluted bleach. Low. The fibers are not a food source for mildew.
Vinyl or PVC-coated Neutral liquid detergent, soft cloth or brush Neutral detergent. Never use acetone, turpentine or degreasers. Low on the face. Higher at seams and on the uncoated back.
Cotton canvas Mild, pH-neutral soap Bleach only as a last resort on bleach-safe white or light canvas: 1 part to 4 to 10 parts water, 5 to 15 minutes High. Cellulose fibers feed mildew.
  1. Take the fabric down before severe weather

    Take it down before snow, ice or the first freeze (32°F, 0°C). Average US first frost dates from NOAA 1991 to 2020 normals include about October 28 for Chicago and about November 19 for Atlanta, per Farmers' Almanac. These are averages, not forecasts.

  2. Brush off loose dirt

    Leaves, pollen and dirt feed mildew. When this step is done, no loose debris remains.

  3. Rinse with plain water

    A shade sail that is only lightly soiled may need nothing more than this rinse.

  4. Scrub with the solution for the fabric type

    Use the table above. Let the solution soak in before you scrub. On water-repellent coated acrylic, spray the cleaner on rather than soaking the fabric.

  5. Rinse until no soap remains

    When the soap is gone, the rinse water runs clear with no suds.

  6. Treat any mildew spots

    Use the treatment for the fiber. If you use hydrogen peroxide, patch test first, because it may bleach colors. Rinse again after treating.

  7. Air dry the fabric completely

    Check the seams, the corners and the back of PVC-coated fabric, not only the main panel. The fabric is ready when every part is dry to the touch. If you have a retractable awning that will stay retracted for months, dry it fully before you retract it.

  8. Dry the storage bags

    A dry cover in a damp bag will still mildew.

  9. Pack the fabric in a breathable bag

    Sealed plastic traps moisture and condensation. Add silica gel packs if the space is humid.

  10. Store the bag off the floor

    Choose a garage, shed or storage room with no water seepage. Keep the humidity below 50%. Leave 2 to 3 inches (5 to 8 cm) between cushions, and do not stack them.

  11. Store the hardware with the sail

    Turnbuckles and shackles left outdoors can corrode.

  12. Check the stored fabric during the winter

    Confirm that it is still dry. The sources give no fixed interval for these checks.

If mildew shows up anyway

A musty smell means the fabric was stored damp, or that the storage space is above 50% humidity. Wash and dry the fabric again. If the musty odor does not go away, Canvas Etc treats that as a sign the fabric needs replacing.

On PVC, seams and the uncoated back are where mildew grows. Clean these areas with neutral detergent. Dry them with the back of the fabric exposed to air before you store it again.

A waterproof cover traps condensation. Switch to a breathable bag. If the space stays damp, move the fabric to a drier, ventilated space.

Canvas Etc lists four signs: persistent staining, brittleness, an irreversible musty odor, or structural degradation.

Next season

The fabric is now stored. It can go back up when temperatures rise and the outdoor season approaches. For stain-by-stain methods on a retractable or fixed cover, see the steps to clean an awning by fabric.

Need to clean cushions, umbrella canopies or shade cloth?

This page gives the makers' care instructions by fiber, including olefin and HDPE shade cloth.

Read how to clean outdoor fabric