Here is a photo from one of the last jobs we did in November. Homeowner called and said dead moss never rinsed off. I'm guessing because it has been so cold and now only just warming up. I can easily pick it up. It feels like dry decomposing wood paper pulp. I'll go back and rinse it off.
We have noticed the summer heat and sun have a large factor when it comes to the break down of moss and lichen. We tell our November customers to wait till June.