Remove any cushions or covers, and set them aside. Vacuum the piece of furniture, using a soft brush attachment, to remove excess dust and dirt.
Take the furniture outside to a shady, dry area.
Mix two tablespoons of ammonia in a bucket with one gallon of warm water.
Use a medium bristled scrub brush and the ammonia mixture to gently clean the furniture. If there are especially small crevices that are dirty, use a toothbrush.
Rinse the piece of furniture with a garden hose set on regular or low water pressure. DO NOT use high water pressure, as this can cause some of the wicker reeds to break.
Dry the furniture as well as possible with a soft cloth, but allow the piece time to dry thoroughly before use, as wet or damp wicker will take on a new shape very easily.