Lichen-covered Decking

Q:   At our cottage up north, we have lichen or moss growing on parts of our deck, the walkway and the steps down to the driveway. Can you suggest an eco-friendly method for eliminating this problem and preventing its reoccurrence?
– Barry Wilkens, Milwaukee, Wis.

A: Lichen is usually whitish or gray, while moss is most often green. In areas where you have lichens: Do you dislike the look, or are you afraid it’s damaging the walkways and deck? While some people aren’t keen on the look of lichen decorating their paths and buildings, others like the rustic look. The likelihood of lichen hurting or damaging surfaces that it clings to is very small.
If, on the other hand, you have moss growing on a wood deck, this can cause more damage. Why? Moss is much thicker than lichen, and thus will hold more moisture, which over time will shorten the lifespan of the wood.

If you’d rather have lichen- and moss-free walkways and decks, there is a tried and true (and eco-friendly) method for removing them: power washing. A soft bristle scrub brush and toothbrush work well too. In the past, one other fairly common option for prevention was to apply a bleach and water solution to moss- and lichen-prone zones, but it’s not the most environmentally friendly option, and it can harm wood decking.

An eco-friendly, off-the-shelf product you can try is Moss-Aside Moss Killer, which can be ordered directly from After the first treatment, this product typically requires an annual application.

Another eco-friendly (but hard to get) product is Orgo’Clean from Flexco (NZ) Ltd. It’s from New Zealand, so you’d need to ask if your local gardening supply store will order it. Made of a renewable plant source, it’s organic, water-soluble, non-toxic and easy to apply. The company recommends applying Orgo’Clean, then pressure-washing the areas after 48 hours. Re-applying the solution every couple years will prevent regrowth. Check out the company at