Moss grows in the Pacific Northwest.  Moss can be treated with a Ferrous sulfate product, which turns it back and “kills” it.

Other things that can help with moss control is to test the soil, test the pH.  A soil test may indicate a need for lime which helps with acidic lawns.  If the lawn is wet, aerating can also help.  If there are thick dense trees, pruning and thinning may help with more sunlight getting to the lawn.  A “Turface” soil modifier can also help with lawn drainage.  They use this product on football and baseball fields.  Be careful with moss control products.  The iron which is an active ingredient in moss control can stain sidewalks.  They sell non staining products. Remember to always read the label on the bag and follow the instructions.

Some gardeners thatch out the moss and reseed.  Some gardeners are content with the “moss application” aerating and fertilizing to thicken up the lawn. Each lawn situation is different.