Wicker furniture has always been difficult to clean, especially if you use it outside on a patio or deck where the dirt just loves to get into every little crack. First you need to remove the dust and loose dirt. To do this, vacuume with the brush attachment. To clean off the dirt and grime, make a solution of 2 tablespoons ammonia in 1 gallon of water. Using a soft bristled paintbrush scrub down the furniture. Rinse well with clean cool water. Let air dry completely and quickly vacuum to remove any left-over dirt.