Although Roundup is very effective at killing weeds and grasses, it won’t kill moss. Instead of Roundup, use a specialized moss killer spray to wipe out unwanted moss growing on bricks or pavers. Alternatively, you can power wash moss off your bricks or spray the moss with a mixture of bleach and water. Clean or power wash your bricks regularly to prevent moss from returning.
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Why Doesn’t Roundup Kill Moss?
Glyphosate—the active ingredient in Roundup—kills plants when it is absorbed by the leaves and carried through the roots and stems by the plant’s vascular system. Moss doesn’t have a vascular system, so Roundup is poorly absorbed and is not circulated through mosses. This means moss will shrug off an application of Roundup even if other plants growing among the moss are killed.
- Roundup works by being absorbed by a plant and passed through the plant’s vascular system.
- Moss does not have a true vascular system so Roundup doesn’t harm it.
- Nearby plants sprayed with Roundup will die but moss will be undamaged.
The weeds, grasses, and other plants that Roundup kills are more complex organisms than mosses. The vascular systems of these plants are similar to the veins in the human body. Mosses, algae, and lichens are simple organisms. They do not build a complex system capable of circulating systemic herbicides like Roundup through the plant. So, you’ll have to use another method to kill the moss on your brick pavers.
How Do You Kill Moss on Brick?
The best methods for killing moss on brick either use specialized moss killers, a power washer, or homemade moss killer mixtures. Our favorite moss-killing tactics are:
- This moss killer spray that is far more effective than Roundup.
- Using a power washer to remove moss from bricks in one easy step.
- Mix ½-cup of bleach with 1 gallon of water (120 ml of bleach in 3.75 liters of water) and spray the mixture on the moss growth.
- Make a 50/50 mixture of vinegar and water in a spray bottle. Then, spray this on the moss.
Power washing is one of our favorite tactics for removing a thick growth of moss on brick walkways and pavers. This is because pressure washing will remove the moss from the brick at the same time it kills it. Other moss killer sprays will kill the moss but you’ll still have to scrape or scrub the moss off later. Using a pressure washer accomplishes both these tasks in one step.
- Kills moss, algae, lichen, mold, and mildew wherever it grows.
- The perfect 2-in-1 killer and cleaner for lawns, patios, roofs, buildings, decks, mulch, and more.
- Kills within hours over a large coverage area.
Does Using Bleach to Kill Moss Harm Brick?
It’s important to note that bleach can discolor brick or concrete pavers if used improperly. However, if you mix 1 cup of bleach for every 2 gallons of water, you should sufficiently dilute the bleach that it will not harm your bricks.
- There is a chance bleach can discolor bricks.
- By diluting bleach at a rate of 1 cup of bleach per 2 gallons of water, you’ll protect your bricks from harm in most cases.
- For extra protection, use this oxygen bleach instead of chlorine bleach—it’s safe for bricks.
If you would like to take extra precautions against damaging your bricks while killing moss, use oxygen bleach instead of chlorine bleach. This bleach variety is far less damaging to your pavers. As another option, use a mixture of vinegar, warm water, and a drop of dish soap to scrub moss off your bricks.
How Do You Stop Moss From Growing Between Bricks?
The best way to prevent moss from growing between your bricks is to keep them clean and dry. However, because moss is more prone to growing in regions that receive a lot of rain, keeping your bricks dry may not be an option. Instead, plan to power wash your bricks 1–2 times per year to keep moss from growing.
- Moss is less likely to grow on clean, dry bricks.
- Power wash bricks 1–2 times per year to clean them and prevent moss buildup.
- Use a bleach solution and a scrub brush to clean your bricks twice per year. This will stop moss invasion.
Instead of power washing, you can clean the bricks with a light bleach solution to prevent moss growth. A mixture of 1 cup of bleach per 2 gallons of water will work to kill or prevent moss. Regular cleaning is the best option to prevent moss growth. Moss loves to grow in the acidic mortar between bricks, so you’ll need to take preventative measures to stop moss invasion.
Will Roundup Kill Moss and Algae on Bricks?
Before you reach for the Roundup to kill off the moss on your bricks, keep these facts in mind:
- Roundup is not effective at killing moss.
- Spraying Roundup may kill desirable plants nearby but won’t kill moss.
- Use a moss killer spray to kill moss quickly.
- A power washer is the best way to kill and remove moss in a single step.
- Scour bricks with a bleach-and-water or vinegar-and-water mixture to kill or prevent moss.
These simple tricks will help you wipe out the moss on your bricks and keep it from returning. While Roundup won’t do the trick for moss, it’s still extremely useful for killing a wide variety of weeds and invasive grasses.