Fill a bucket with warm tap water. Add three or four squirts of liquid dish soap to the water.
Spray the furniture with a garden hose, using a sharp spray. Rinse away as much loose dirt as possible.
Scrub the furniture with the soapy water and a soft-bristled brush. Car-washing brushes work well, as they help loosen dirt without scratching the finish.
Rinse the soap and grime from the furniture. Scrub any areas that still remain dirty a second time, then rinse again.
Storing wet furniture can lead to mildew growth, so prior to storage, set the furniture out to dry thoroughly, or dry it with towels to reduce water spots.