Control Moss With Laundry Detergent

I live in the Pacific Northwest where every year the skies are filled with clouds 226 days and rain 155 days. These are ideal conditions for growing moss. If left unchecked moss would cover my roof, driveway and sidewalks. I even have some moss growing on my car!

Any powdered laundry detergent should kill moss. I use Costco Laundry Detergent, it's the same powder I use to wash our clothes. I have used home improvement center moss-control products, but found them to be expensive, toxic and don't seem to work as well.

I mostly use the detergent treatment to control moss on the roof of my house. It's more than an appearance issue, moss shortens the life of shingles and causes leaves and needles to accumulate which contributes to leaky roofs. To illustrate how well detergent works, I treated a section of concrete wall next to my driveway.

For this demonstration, the left side of the wall was untreated and the right side had a light sprinkling of detergent. Only a little detergent is needed. On my roof, I only sprinkle detergent on the ridge lines and let the rain deliver it to the moss growing on the edges of the shingles. Sometimes I treat persistently mossy areas with a direct application like the roof corners or along a gable.

Here are the results after just seven days and a couple of light rainshowers. From my reading, moss requires a pH of 6-7 and laundry soap has a pH of 9.

Did you think I was kidding about the moss on my car?