Getting rid of moss from a driveway can be frustrating because of how resilient the plant is. It bounces back easily and quickly.
But there are some products, both commercial and homemade, that will kill moss and keep it away for a long time. In this post, I talk about some of the best moss killers you can use on your driveway.
What You'll Learn Today
Why Is It So Hard To Permanently Get Rid of Moss?
Temporarily getting rid of moss is easy. A stiff brush or power washer is enough to clear it from the driveway.
But getting rid of it for good is a lot harder. Once you remove it, it can grow back within just a few weeks.
Moss grows easily on a wide range of surfaces and in a variety of weather conditions. As long as there is some moisture on your driveway, it will reappear.
Because moss doesn’t need much sunlight to photosynthesize, it grows even during winter and autumn. In summer, it may lose its green color but it doesn’t die. A bit of rain and it will spring right back up.
Moss is so resilient and adaptable that it’s found in every climate region on earth including the arctic and even under water. There’s even a desert moss.
But the main reason why moss is so hard to permanently get rid of is that homeowners don’t fix the root issues that are causing moss to grow on the driveway.
No matter what chemical you use or how hard you wash the driveway, if you don’t get rid of the dampness that’s attracting moss, it will come back. In most cases, this involves improving driveway drainage.
Best Commercial Moss Killers For Driveway
As you plan how to fix your driveway to permanently get rid of moss, there is a wide range of commercial moss killers you can use to kill moss and keep it away for months.
There are three main types of store-bought moss killers.
Iron Moss Killers
Iron based moss killers are the most effective. The most commonly used iron compound is iron sulfate.
Iron sulfate is typically used to deal with moss on lawns. It improves the health of the turf while at the same time making it hard for moss to survive.
But you can also use it to kill moss on hard surfaces such as patios, walkways and driveways. It’s available as a powder, granules or liquid. You can apply it directly onto the driveway or mix it with water and then apply (check the instructions on the label).
Iron sulfate works quickly to kill moss. You’ll notice the moss yellowing within a few hours. It’ll be dead in a few days and you can easily brush or wash it away.
The main downside with an iron sulfate moss remover is that it can easily stain your driveway. Test it on an inconspicuous spot before applying it on a larger area.
Potassium Moss Killers
Potassium salts of fatty acids, also called soap salts, are commonly used in insecticides, herbicides and fungicides.
Potassium based moss killers are less likely to stain your driveway, though they take longer to kill moss.
Similar to iron sulfate, potassium salts attack moss without damaging the lawn and other plants such as flowers. But be careful with application, as too much of it can burn certain plants. Spraying is the best method of application.
One big advantage of potassium moss killers is that they are mostly eco-friendly. They break down quickly in the soil and the potassium salts are non-toxic to birds.
However, potassium salts are slightly harmful to fish and highly dangerous to aquatic invertebrates. Avoid using potassium moss killers close to a water body. It’s also a good idea to only apply the moss remover when it’s not raining to avoid potassium-containing runoff from getting into the water.
Zinc Moss Killers
Zinc sulfate is another safe alternative to iron sulfate if you don’t want to risk stains and discoloration on your driveway.
Zinc sulfate has many of the same eco-friendly properties of potassium salts. It’s good for plants, it breaks down quickly in soil and it is generally harmless to birds.
But similar to potassium salts, it is harmful to aquatic life, and especially aquatic invertebrates.
Zinc sulfate kills moss as soon as it comes into contact with it, but the moss will take a few days to yellow and completely dry out. If you have a thick layer of moss, it could take a few weeks for it to fully die.
Other Compounds
There are several other types of salts that are found in moss killers. One of them is benzalkonium chloride, which kills moss as well as mildew, mold, algae and fungi.
When properly applied, benzalkonium chloride will protect your driveway from moss for up to one year.
Always check the active ingredient in a moss killer before you buy it. Then look up how effective it is on moss, how long it takes to kill moss, and how often you need to apply it.
Also check whether the active ingredient is environmentally-friendly and safe for your lawn. The last thing you want is to turn your lawn brown.
Best Homemade and Natural Moss Killers For Driveway
Store-bought moss killers can be pricey, especially because you need to reapply them regularly to keep moss at bay.
If you are looking for a cheaper moss killer, you have several options in your home. These include easy to find chemicals such as bleach as well as natural products that are safer for aquatic life.
Bleach
A solution of household bleach and water will turn moss on the driveway yellow in a few hours. You can also use stronger bleach (10-20% sodium hypochlorite) if you have lots of moss on the driveway.
Unlike the salts we’ve discussed above that are generally safe for your lawn, bleach will kill plants it comes into contact with.
Be careful to spray it only on the driveway.
Also be careful if you have paint or sealer on your driveway. While bleach is safe for bare concrete and asphalt, it can erode sealer or paint.
To be safe, use a dilute solution of bleach. 20 ounces of bleach in 5 gallons of water is enough to kill the moss. After application, let the solution soak into the moss for 15 minutes then rinse it away.
Vinegar
Vinegar will also kill plants non-discriminatively, so you want to be careful how you apply it. Make a dilute solution in a 1:1 ratio then spray it only on the areas with moss.
Vinegar can also remove mold, algae and weeds from your driveway.
Baking Soda
Baking soda kills moss by raising pH. But it works a lot slower than other methods. You need to give it a few days for it to completely kill the moss.
You can apply the baking soda directly onto the moss or mix it with water and spray it onto the moss.
As with all the other products above, baking soda is bad for your lawn and other plants. Be careful when applying it. Don’t apply it when it’s raining or about to rain as the water could wash it onto your lawn, killing grass.
Boiling Water
If you want an all-natural way to kill moss, try using boiling water. The hot water instantly kills moss on contact, along with any weeds or grass growing on the driveway.
Then you just wait for the moss to yellow and dry out. You can then wash or brush it away.
Using boiling water is safer for your lawn compared to the other methods above. Even if the water runs off onto the lawn, it will have already cooled down and won’t damage the grass.
Scrubbing/Pressure Washing
Another all-natural method to kill moss is washing the driveway. Use a stiff brush to scrub it away or a power washer to blast it off the driveway.
Here’s a satisfying video of moss being pressure washed off a driveway.
Do Weed Killers Work On Moss?
You may have noticed that moss killers are a whole separate category of herbicides from weed killers.
Mosses don’t have roots or a vascular system that transports weed killers throughout the plant, which is what happens in other plants. So even though weed killers like Roundup have no effect on moss.
When you go shopping for a moss killer, make sure it’s specifically designed to kill moss. Do not pick a general herbicide or weed killer, it may not work.
Final Thoughts
From my research, store-bought moss killers are better than homemade moss killers in almost every way.
Many people are concerned about harsh chemicals in herbicides, but moss killers are surprisingly safe for the environment. In moderate amounts, potassium, zinc and iron salts are actually good for your soil and lawn.
They are also highly effective at killing moss and preventing it from reappearing for a long time (usually several months).
Instead of risking damage to your lawn by using vinegar or bleach, I recommend picking up a moss killer from your local gardening center or buying it online.
How is it that natural elements like iron, zinc and potassium are so good at killing moss?
These plants like a great deal of moisture in order to survive, and compounds like the above are very good at removing water from the surroundings, which will kill the moss faster than just about anything else. You can buy these things at most garden centers to help deal with your problem.