Machine washing is fine!
Ted:I would recommend that you use a hose and soft brush to clean off the spots before you put it in the washing machine. Rather than explaining the ins/outs of the process, you can go directly to the Sunbrella site for washing directions.http://www.sunbrella.com/usa/ Look at their 'Questions' section on the left hand side of the site. There are washing instructions there.When you are done washing, let it dry and spray with some "303" protectant that is made for Sunbrella.