Although beneficial to the eco system, there may be times when you need to remove moss from your property. On driveways, stairs, or walkways moss can be very slick and slippery as it absorbs water. On roofs and siding, moss can start deteriorating the material, compromising the performance and making the home look devalued. Moss creates a perfect environment to host other seeds, weeds and flowers to grow – so a moss covered roof may eventually have weeds growing on top of it, causing the roof to buckle and warp. Moss is actually quite useful in our environment and can be very beautiful. Often found growing on tree trunks, rocks or over the landscape, moss is soft to the touch and can help with erosion. During World War I, moss was sometimes used as a bandage, as it easily absorbed more liquid than cotton and has mild antibacterial properties.
Most of us know that moss likes to grow in humid, cloudy conditions. The best way to protect your paved surfaces from moss growth is to prevent moss spores from growing in first place. Spores settle in cracks and holes where soil and water collect. Regularly sweeping your driveway, roof or walkway will help prevent spores from settling on the surface. Trimming overhanging branches and allowing more sunlight to permeate the surface will also deter moss growth.
To remove existing moss there are plenty of off-the-shelf chemical solutions but using them may not be great for surrounding plants and wildlife. These chemicals may run into our waterways and streams and may be harmful long-term. Fortunately there are many less-harmful, and inexpensive, methods of removing moss from driveways, patios and walkways.
Renting a pressure or power washer, purchasing one with a neighbor, or hiring a pressure washing contractor, is an excellent method of removing moss. The pressure washer uses a powerful stream of water to remove just about anything stuck to the surface. Be aware that this stream of water may remove more than you want and it’s not recommended to use on standard shingle roofs or wood siding. In other words, test your surface first prior to using. Power washers are very effective at removal but regular maintenance will still be required. Also, most machines require gasoline and use quite a lot of water -which may not fit everyone’s idea of a “perfect” solution. Read more about how to pressure wash here.
Washing Soda or Soda Carbonate
Not to be confused with soda bicarbonate (baking soda), washing soda (otherwise known as washing crystals or soda carbonate) is a naturally occurring and highly alkaline chemical. Its high alkaline nature will kill existing moss. This video demonstrates how easy it is. Simply sprinkle the soda carbonate on the moss, sprinkle water on top of it and leave it to sit for several days until the moss turns brown. Once this is complete you can scrub or scrape the moss. Obviously this process is time consuming and you’ll want to wear protective gloves (the alkaline properties can harm your skin) and keep out of the reach of children and pets. This type of alkaline material is similar to what is used in roofing de-mossing products.
Vinegar contains acetic acid, weak enough for humans to consume but strong enough to kill moss. To use, simply pour white vinegar directly on the moss and let sit for 30 minutes. Rinse or scrape the moss away. The downside is that depending on your area of moss coverage you may need to purchase lots of vinegar. And you’ll want to make sure that the vinegar doesn’t get a chance to seep into surrounding plants as it will negatively affect their health. Some roofing experts don’t recommend using this product on your roof.
Homemade Moss Killer
This “recipe” is made from inexpensive ingredients you may already have at home. Combine water, vinegar, salt and soap with the following ratios: 1 gallon of warm water, 1 tablespoon of vinegar, 1 pound of salt and as much soap as you want as long (as it’s not more than 20% of the mixture). Pour the mixture into a spray bottle and spray directly onto the moss. Once the moss has turned brown it’s time to scrape it off the surface and discard. As you can imagine, this moss killer will also kill other plants so use caution when spraying.