What is Wicker?
Interestingly, wicker is not an actual material but the end result of the act of weaving chair seats and furniture. Common materials used in the construction of older wicker furniture were rattan reed and paper fiber rush. Sometimes cane, rush or splint seat furniture is referred to as “wicker,” but the materials used in the woven seat and the design or pattern more correctly refers to them (see Reference 1).
Removing Mildew Stains
To remove mildew from wicker, fill a spray bottle with one part laundry bleach and nine parts water and spray the entire piece of furniture where you see the mildew until it is very damp. It is best to do this outside in the sun because the sun aids in the bleaching process. Repeat this process until you begin to see the mildew stains disappear (see Reference 2). You can also use ammonia in place of bleach. Let the cleaning mixture sit on the furniture for at least five minutes. Residual bleach can damage wicker, so be sure to rinse the furniture thoroughly.
Tips
Of course, the best way to remove mildew from wicker furniture is to not allow mildew to form in the first place. Wicker, although it looks pretty outside on a patio, is not outdoor furniture. Rain, direct sunlight, and dew are extremely damaging. If you really want to use wicker furniture outdoors, bring it inside when you are not using it.
Do not store wicker furniture in a basement, as the dampness is a haven for mold and mildew. Dry indoor heat will dry wicker and cause it to crack and creak under pressure. Wipe it occasionally with a damp, not wet, cloth.
Warnings
Never combine ammonia with bleach because the two chemicals together give off toxic, deadly fumes (see Reference 3). Clean wicker furniture in a well-ventilated area. It is best to do so outside.