Dawn Ultra liquid dish washing detergent can be used to kill moss when diluted with water and sprayed under pressure. Soapy liquid is a less expensive and greener alternative to chemical treatments. Dawn Ultra kills by inhibiting the ability of moss to draw water. The moss turns brown or orange within 24 hours, and dries up.
Pour 10 oz. of Dawn Ultra into the pressure sprayer.
Add two gallons of cold water.
Pump the sprayer to achieve pressure.
Spray the solution directly on moss, thoroughly saturating the area.