Is there an environmentally friendly way of killing mosses and lichens growing on steps leading to the dock?
Mosses and lichens are hardy—that’s why they’re all over cottage country—and the only earth-friendly way to get them off your wood is elbow grease. Unfortunately, this won’t keep them from returning. Rotting wood—like the kind you might find in an old dock—is the perfect substrate for mosses. And lichens grow on the wood simply because wood is a good place to live. Both lichens and mosses grow on healthy wood too, so their presence doesn’t always mean your dock or boathouse is rotting. While the growths won’t cause your wood to rot they absorb moisture, making rot more likely. Also—wipeout alert—lichens lead to slippery surfaces.
Lichens grow at a molasses-like rate, so once they’re scraped off, you won’t need to scrub again for a few years. But in a combination of moist, sunny, and warm conditions, mosses grow faster, and might need to be removed once or twice per season. Make the wood less hospitable by keeping it drier (trim back trees, for example, to allow more sun on the area).