De-Moss Your Yard

By AM Northwest Staff


Moss: Is it beastly or beautiful? At minimum it can be an annoyance to clean off your brick patio or roof.

We had Metro's Natural Gardening and Toxics Reduction Specialist, Carl Grimm here to show us how to get that moss under control!

Here are his tips:



Moss is a primitive plant that dinosaurs used to eat—It has no flowers or vascular system, and includes about 10,000 species! Moss thrives in moist shady spots and on poorly drained acidic soils.

  • Letting it be is not just pretty, but also can reduce our dependence on garden chemicals that could otherwise harm people, pets and wildlife.
  • You see, some chemical moss killers for example contain copper which washes off the yard into storm drains and into local rivers where is affects salmon’s olfactory system and navigation ability.
  • So, if you want salmon to find their way back—let the moss be!
  • Visit the Japanese Garden in Portland’s Washington Park and you will see how beautiful moss can be. This is a little stone house loaned us to give you an idea…



  • On paths be sure to scrape or pressure wash all slipping hazards! I like to use a triangle paint scraper or small garden hoe for bricks and fences, or , for long cracks, a machete. A pressure washer makes short work of big jobs.
  • On roofs be very careful not to hurt yourself and not to damage the roof! Call an experienced friend, relative or professional if you are concerned about climbing ladders. Either way:
    • Prevention is the first step: remove all overhanging branches and sweep leaves, needles and other debris off the roof regularly.
    • To remove existing moss, get someone experienced to carefully scrape or wash it off without harming the shingles.
    • For minor infestations on roofs or patios, an herbicidal soap spray and gentle sweeping may do the trick. Do not apply during rain.
  • In lawns I like to leave the moss since it does not need mowing, chemicals or fertilizers. But if you need tougher turf, you may want to…
    • Trim branches to let more sun in to dry moss out.
    • Rake out the moss—a thatch rake works best.
    • Aerate by removing soil plugs and topdressing your lawn with compost to improve drainage. (If soil is acidic, you can also add some lime.)
    • Then always be sure to mix grass seed into your compost topdressing to help your lawn out-compete weeds.



  • Whenever possible, let moss be a part of your landscape.
  • Some say they have luck with smearing mud, clay, yogurt and shredded moss on rocks to foster moss. But ultimately, it is the shade, moisture, and clay soil that really gets it to grow.



More information: call 503-234-3000 or visit here.


For the Japanese Garden website website.


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