Moss grows fat on my (unmoving) stones (well, stairs)

February 21, 2014 11:31 AM

I have brick stairs to the front and back porches. They tend to get lots of moss growing on them. How can I get rid of the moss ?

One set of stairs is pretty well shaded, the other gets near full afternoon sun. Moss grows all over -- off little divots in the brick, in the mortar along the tread, at the tread/vertical junction, on the side of the staircase, etc.

I've scraped with a metal brush. Doing it twice a year, and it works "sort-of". I can't get the bristles into the nooks and crannies as well, but it gets the big pieces off the brick. It's also very labor intensive.

I've tried roundup (read to use it to control moss somewhere), but it didn't make a difference.

I've been told "power washer on low." I have access to a power washer, but am reluctant to power wash brick (blast the mortar away, etc).

So are there other/better ways to control/kill the moss growing on my brick ?

posted by k5.user to Home & Garden (10 answers total)

I'm pretty sure my parents used bleach.
posted by radioamy at 11:39 AM on February 21, 2014

They sell stuff called roof moss killer at Home Depot, etc. In the PNW here there's a powder most folks use. Maybe this is helpful:

http://bryophytes.science.oregonstate.edu/page24.htm
posted by humboldt32 at 11:49 AM on February 21, 2014 [1 favorite]

Yeah, the northwest tactic is to use iron. Iron sulfate, often. It stains concrete, but it kills the moss delightfully.

If you do this, you'll probably want to spread lime in your garden in the spring to counteract the acidity. If your garden is delicate, you're stuck with the stiff-brush option.
posted by janell at 12:02 PM on February 21, 2014

I've got a brick patio that I've had good luck with the "power wash on low" routine; it comes back a little less every time. You can also just spray with a bleach and water solution which will help keep the stuff from getting a foothold a lot of the time.
posted by jessamyn at 12:30 PM on February 21, 2014 [1 favorite]

Yeah, power washers have variable pressure settings (and/or different nozzles) to help control the output pressure. That's how you can use the same power washer to rinse your car or strip paint. A low power setting + spraying a mixture of water and moss inhibiting agent, like bleach, will do wonders for reducing or eliminating your moss problem.
posted by mosk at 1:00 PM on February 21, 2014

White vinegar before and after scraping, on a sunny (preferably warm) day. And if you can cut back some of the foliage that is shading that one set of stairs that might help a little.
posted by rmless at 4:21 PM on February 21, 2014

Bleach spray.
posted by BlueHorse at 7:19 PM on February 21, 2014

I use vinegar too. I can't stand the smell of bleach.
posted by freakazoid at 6:00 AM on February 22, 2014

Response by poster: So for vinegar or bleach: do you dilute it any, or straight from the bottle ? (Leaning towards them as a first try, since I have both on hand .. )
posted by k5.user at 12:49 PM on February 22, 2014

Dilute bleach: cup of bleach in a gallon of water, more or less. I think you can dilute vinegar 50/50 if you want your patio to smell less vinegary.
posted by jessamyn at 1:55 PM on February 22, 2014