If your roof is looking a bit mossy, it's important to take action and do something about it. Allowing moss to continue growing on your roof could cause your shingles to break down prematurely, and before you know it, you'll be catching drops of water in buckets and scurrying to call the roofing repaircompany.
A common method for getting rid of moss is to scrape it off and then spray the roof with a moss-specific killer. While this method is generally effective, it does have a few consequences -- it's not great for the environment, and it tends to kill the surrounding foliage, leaving garden beds barren as rain carries the herbicides off of the roof.
You don't have to resort to harmful chemicals to keep your roof moss-free. This natural method may take a little more time and effort, but you'll be doing the environment (and your yard) a favor:
Step #1: Get rid of as much moss as possible.
Stand on a ladder, and use a long broom as you have to. It's easiest to push moss off of the roof just after it has rained, when both the shingles and the moss' roots are moist. Make sure you remove all of the freed moss from the roof, too, so it does not prevent the natural moss-killing solution you'll soon apply from coming into direct contact with your shingles.
A leaf blower comes in handy for this task. Just blow the loosened moss off your roof.
Step #2: Prepare your moss-killing solution.
All you need is 6 cups of baking soda, 1/2 cup canola oil, 1/3 cup castile soap, and 4 gallons of water. Prepare this mixture in a bucket, and mix it up well.
Step #3: Spray your roof.
Unless you're able to find a very powerful sprayer, you'll probably need to climb on your roof to spray it with this mixture. Wait until the roof is dry and no rain is predicted, so you don't risk falling on slippery shingles. Make sure a buddy is there on the ground, just in case you need help.
Fill your sprayer (a pressurized, backpack-style sprayer works best) with your solution, and then apply it liberally to your roof. You may need to make a second batch if you run out. It's better to use too much than not enough.
If you repeat this process every spring, you should notice the amount of moss on your roof quickly decrease. Keep in mind that moss loves shade, so if you have trees overhanging your roof, trimming them may also help keep the problem under control.