How would I get off an inordinate amount of green moss on the roof?

Patty, Moss means too much moisture and not enough sunlight. This needs to be peeled

or brushed off. Can you cut limbs to allow more light to get to that area?

The black mold-like stains and streaks that appear on roofs, particularly light-colored asphalt shingles, is actually a blue-green algae (Gloeocapsa magma). Commonly found in climates with warm, humid summers, it does no damage to the roofing, but it certainly does looks bad.

The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first, and rinse everything in clean water when you're done. Plants don't like bleach, and wetting them with plain water first protects them. You can also cover them with tarps or plastic sheeting, which will protect the soil around your plants as well. Make sure that you create a wide radius around your home to be safe.

Allow the solution to soak into the shingles for at least 15 minutes. If they are severely molded, you may want to give it a little longer. Next, rinse the shingles thoroughly with a garden hose at low pressure. Start from the top shingle and rinse downward to prevent water seepage.

To keep the algae from coming back, insert 6-inch-wide strips of zinc or copper under the row of shingling closest to the roof peak, leaving an inch or two of the lower edge exposed to the weather. That way whenever it rains, some of the metal molecules will wash down the roof and kill any algae trying to regain a foothold on your shingles.

You can probably see this same principle working on roofs in your neighborhood. Look for chimneys with copper flashing; the areas directly below the flashing will be free of any algae stains.

The strips also work on roofs suffering from moss buildup. Just scrub it off first with a brush, then bleach as above.

We have a friend who is a chimney sweep and he uses the cheapest dishwasher soap he can find. Just sprinkles it on the roof at the peak before a rain storm. The rain washes it down the roof top and it kills the moss. It would help to use a scrapper to remove as much as possible first.

Or you can sprinkle the detergent on the moss, let it sit for three to four days, and then sweep the dead moss off of the roof.

the idea that the moss only grows in the shade and under high humidity conditions is false. On the contrary, there are mosses suitable for all conceivable conditions: dry or wet spots, shade or full sun, acid or alkaline surfaces, etc.. spray the area with one of the various anti-moss products (prefer an organic soap such as EcoSense Moss B Gone, widely available in garden centers) to kill the moss initially.A stiff floor brush or actual roof brush(walmart) and strong spray nozzle/cannot really use power washer it will damage shingles. The dead moss will be easier to scrape off.another way The less expensive solution is to spray wash the roof with a 50 percent mix of water and bleach to get rid of the algae. (No pressure washers, please. They're likely to damage the shingles.) Just be sure to wet your foundation plantings first really well so you don't kill them , and rinse everything in clean water when you're done.

Around here in the PNW, we shake Moss Out in the can on the roof in the spring and the fall, especially north facing roofs. You can also buy it in a hose attachment bottle in liquid form which is my go to..... as I can't get on the roof anymore