How do I remove moss from an outdoor brick walkway?

Question

I've got a brick walkway that has parts that are in shade most of the day. Our winters are wet and cloudy and during these times it's not uncommon for the shady parts of the walkway to grow a fair amount of moss on the bricks and grout (see the photos below).

Come summertime, the moss dries out and dies and can be hosed off quite easily. However, I have family coming in for the Holidays and would like to remove the moss pre-emptively, as it's both unsightly and slippery.

Any advice/suggestions on how best to remove the moss? My first thought was to just get down on my knees and scrub it off, but my concern was that it would grow back in short order. Would using bleach or a bleach-like product have a more lasting effect, or would using such a harsh product outside where there is grass and plants nearby be an unwise move?

Finally, is there any preventative steps I can take to reduce the quantity of moss that grows during our wet season?

Answer 1

My immediate vote is for a pressure washer. They are relatively cheap these days. Lacking that, a simple high pressure hose nozzle and a good stiff brush will do well too. Various oxidizing bleaches will also work, all of which will last for only a limited time.

To stop it from returning is difficult, since any moist, shady spot under a tree or bush is likely to grow moss and algae of this sort.

One idea is to remove the overhanging growth from the planters. Trim them back. This will help the brick pavers to dry out, and will reduce the tendency for unwanted growth.

Another idea is to get creative, and buy some zinc strips. Copper flashing might work too, but they sell zinc strips specifically for roofing applications, where moss and algae tends to grow on roofs. The elemental zinc leaches out (very slowly) when it rains, which in turn inhibits growth of the algae where it leaches out. So you could afix these strips to the bottom edges of your planter. Make it decorative and it should help, although I cannot assure it will work perfectly. At least this will inhibit the moss.

Another idea is to buy/make a few copper pots or planters. Place them decoratively right on top of the problem spots. As the copper leaches out from weathering over the years, it too will inhibit growth on the walkway, you not be a problem for larger plants in the area. If you cannot find a pot you like, you can make a planter from wood, but then wrap copper flashing around it, nailing it in place.

Be creative if you wish to inhibit the growth.

Answer 2

Powerwashing will certainly get rid of it, but that will not be a preventative measure.

Answer 3

I would try oxygen bleach, like Stainsolver.com. It is not harsh for grass and plants.

Answer 4

After you power wash, use some water and dish detergent, don't rinse it off. We have mold problems here in BC and it is a deterrent that works. It doesn't get rid of it forever and will need to be repeated but it will slow down the development.

Answer 5

I have a very large patio with bricks. An unsightly mess in the damp winter. We end up with greenish blackish slime. A power washer (powerful one) just water, gets them clean like brand new bricks. You just have to take your time and stick to one brick at a time. Very tiring. When the sun comes out in the summer our bricks are easy to clean and stay bright Tuscan red. Nonetheless, I am contemplating covering half of the area with a raised pea gravel (beige or rust color) to reduce maintenance. I am fed up. Bricks are only beautiful when they are spotless, and when I am not power washing I am sweeping to get the dirt off! Takes the pleasure away fast. Of course we are in a damp area so my problem is surely worse than yours. No need for chemicals. I am sure there are products that you can apply to keep the moss from building up and soaking in however, as soon as you pull out the power washer that protective coating will be soon washed away. In fact, my power washer if I go to town with it, will eat right into the bricks and sand blast my windows. Pain in the butt!!!!!