copper sulfite solution, a moss treatment?

Asked March 18, 2016, 5:36 PM EDT

May I spray safely a copper sulfite solution to fight moss covering a ground cover of lava rocks? I have 8 yr old fir trees growing in that area. If the answer is "yes," what concentration is advisable? Thank you, Ingeborg

Benton County Oregon

1 Response

It's going to be difficult to control moss growing in shady areas in Western Oregon. Our mild wet winters are just perfect for abundant moss growth! The typical management methods we recommend for hard surfaces (like pressure washing) are going to be difficult in your situation. Copper sulfite is currently not registered as a pesticide against moss. If you want to try to use a chemical spray, then your best bet is to find a pesticide that is a soap registered for controlling moss. Safer is one brand that many garden centers carry. (There are other products that are acid based which are also effective but may discolor or stain your lava rocks.) Make sure to read the label of which ever product you purchase to ensure that it can be used on stone surfaces, will not discolor or staying and for the application and safety instructions.
Good luck and thanks for using Ask An Expert!