Roof moss removal. Roof moss season has ended, however if moss is growing on your roof - we can discuss with you the condition of your roof with possible remedies for cleaning anytime between now and March moss treatments. If the moss growth is well on its way, it may need to be removed first then what remains, treated. If it's in infancy, we can treat it with a environmentally friendly moss suppressor. The moss would die and slowly make it's way from your roof into the gutters over a few months. December would be our gutter cleaning season.