Moss Between Pavers

House Doctor | Gary Dymski

May 31, 2001

Q. What is the best way to clean a brick patio of grass and moss that grows in between the sand joints? We have a concrete foundation under the brick paving stones, yet weeds and moss still grow in the sand joints.

-Margie Kulik, Ridge

A. Moss often grows on pavers in shaded areas, especially if your foundation doesn't have proper drainage. In cases where pavers are installed over a concrete foundation, weep holes are often drilled into the foundation. These holes allow moisture to drain into the ground beneath the foundation after it has penetrated the sand joints.

I don't know if you have the ability to do this, but removing a couple of paving stones and drilling weepholes might provide a solution to standing water. Be sure you have replacement stones, however, because you'll likely have to break at least one stone to gain access to the foundation.

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If this seems like too much work, then use a solution of bleach and water (1 part bleach to 4 parts water should do the trick) to remove the moss and any mold or mildew that might form. If your moss growth is so strong that you find yourself bleaching the pavers every other week, try using a solution of copper sulfate instead. Be careful, though, because copper sulfate might damage the surface of the paving stones. Try mixing an ounce or two of the copper sulfate crystals (available at agricultural supply stores) to a quart of water and then test it on an obscure part of the patio to see if it damages the pavers. If it doesn't, try scrubbing it into the affected area with an old broom. Let it set and then rinse with water.

Another warning: Copper sulfate is a pesticide and can kill plants around the patio. Again, use it carefully.

Another common problem is weeds growing in the sand joints between pavers. They're easy to remove because the joint restricts their root system. If you don't like to pull, use boiling water on them.