How to clean concrete mold and moss

How to clean concrete mold and moss

There are a few things that could look better on structures. Mold and moss are two of them, as they promote moisture and dirt that let them prosper in the above structure.

You might have noticed some and tried removing mold and moss, but it keeps growing back twice as hard.

While natural growth can be beautiful in places where we want it, like old soil support structures, it can be an annoying problem if it’s happening with your new driveway. You try to wash it with a pressure washer, but it keeps coming back no matter what.

Now, you don’t have to worry about mold and moss growth any longer, as there are ways to get rid of them for good. You have to prepare to work smart about it.

I’ll show you two cheap alternatives, and you can check if they would fit well.

Concrete life cycle shortly

It’s good to look at the process to understand why something happens.

A natural occurrence for concrete is that it will appear weathered when exposed to moisture cycles over a long period. Concrete surfaces that remain wet for extended periods promote mold and moss growth.

Either the place or other factors won’t let it dry.

Is moss on concrete harmful? In some places, it is not, but as it promotes moisture with time, it can harm the structure.

Depending on the cycle time it takes the concrete surface to dry, the weathered surfaces can appear grey, black, or green.

Several products on the market today can renew the appearance of these materials. However, they are usually in the fifteen to twenty dollar per gallon price range. So, what do you use to clean concrete cheaply?

You may have one or two everyday household items in your house right now that can produce the same results at a fraction of the cost. The first common item is bleach, which you purchased for under two dollars per gallon.

The second one is Vinegar, which should also be in the same price range.

One noteworthy thing is that bleach only kills mold from the surface. There are also claims that it can promote mold growth.

Vinegar is another traditional and less toxic alternative, so I’ll explain both of them. Vinegar is also better for porous surfaces like concrete and can kill mold and moss on a deeper level.

How to clean concrete with bleach

Knowing the effect that bleach can have on clothing, wearing clothing you are willing to throw away after you’re done is recommended. It is also a good idea to wear rubber gloves that cover your arms and protective eyewear.

Depending on the size of your project, you will need a pump-style garden sprayer with a tip that fans out the spray. Then, it would help to have a stiff bristle scrub brush and a garden hose with a pressure nozzle.

You may also need a power washer for cases with heavy mold or moss concentrations.

Light moss and mold and staining

This is the damage I’m most optimistic about when cleaning with bleach. If there is only light mold or moss, it doesn’t run too deep, and there is a good percentage for success.

The first thing that you need to do is to pour the bleach undiluted into the garden sprayer. Spray the bleach directly onto the surface evenly and allow it to sit on the surface for a few minutes.

You will see the transformation occur almost immediately.

If you’re concerned with the color of the surface changing, you can also dilute the mix. It could be more effective.

For badly weathered surfaces, you will need to brush the bleach into the surface. After allowing the bleach to remain on the surface for a few minutes, rinse the surface thoroughly with clean water. If needed, you can repeat the same process over again.

Depending on how deep the moss and mold are in the pores, it might be hard for the bleach to work perfectly. Moss shouldn’t be a problem; exposing it to a less moist environment can also affect its growth.

Before committing to the process, I’d consider how much the procedure would cost for the area. If it’s cheap, why not try it out?

Heavily molded surfaces and heavy moss

You will need to use the trial-and-error method for severely weathered surfaces. First, apply the bleach and then use a power washer or visa-versa. I’d start with washing with a pressure washer to see how much will be left by water.

After the surface is washed, the previous bleach and brush process can be repeated. Also, be careful with a pressure washer; you want to wash it sparingly, or it will leave marks on the concrete. Depending on the power of the pressure washer.

After the bleaching process, wash the garden sprayer with purified water. Make sure to spray the water through the hose so that you do not leave any bleach in the spraying mechanism, which could cause corrosion.

This should work out for moss, as it’s good for killing plants and such. But for deep-run mold, more is needed.

Using bleach to clean concrete might promote more mold growth

How to remove moss and mold from concrete naturally

Vinegar can be synthetic or naturally obtained. You can look up one from an organic source if it concerns you.

Vinegar might harm the skin, so it’s also good to use protective gear here. The good thing is it is even more harmful to mold and moss, so if bleach isn’t working, this should do the trick.

The cleaning process here is the same. We need to spray white Vinegar on the mold and moss. We can use the Vinegar undiluted, so it works better if the problem is stubborn.

Being more organic, Vinegar may need more time to work out well. It’s also a matter of how deep in the pores of concrete the problem is.

It needs to be on the surface for around 60 minutes before brushing. Again, this is a process we repeat until we have a good-looking concrete surface. When finished, wash the concrete with a garden hose and dry it.

Concrete is porous; sometimes, the mold and moss are deep in it, waiting for chances to grow back. In those situations, you should repeat the process and let it affect the concrete even longer. Eventually, they should give in.

Also, as a warning, Vinegar harms some surfaces like iron and some natural stones. Avoiding those is good; if you have some, consider adding some protection.

Will vinegar kill moss on concrete? Yes, and mold too.

The final part is sealing.

As mentioned before, our problem is that we have a porous surface. We should aim to fix this problem permanently by filling those pores with something useful.

After allowing the cleaned surface to dry out completely, you can apply a penetrating sealer to prevent the weathering process from re-occurring.

It will seal the pores, so growth has a more challenging time sinking in. As the concrete stays clean and is easy to keep, you will have an easier time with these problems.


Mold and moss can be quite stubborn and challenging to remove from concrete surfaces since they tend to penetrate deep into the pores of the material. Removing them can be difficult and, in some cases, even counterproductive, as it can stimulate their growth and cause them to spread even further.

However, vinegar is an effective and natural solution for tackling mold and moss on concrete surfaces. Vinegar contains acetic acid, which can penetrate deep into the concrete, dissolve the mold and moss, and prevent them from growing back.

However, it is worth noting that prevention is always better than cure when it comes to mold and moss. One way to prevent the growth of these unsightly organisms is to seal the concrete surfaces.

Sealing the concrete creates a barrier that prevents moisture from seeping in, which is a key factor in the growth of mold and moss. Additionally, sealed surfaces are much easier to clean and maintain than unsealed ones, so they offer long-term protection against mold and moss growth.

In summary, if you’re looking to keep your concrete surfaces free of mold and moss, vinegar is an effective solution for removing them, and sealing the surfaces is an excellent preventive measure to ensure they don’t return.

In the ultimate bad situation where nothing works, and I’m tired of cleaning the surfaces, I’d go for the top resort, grind the surface, and resurface it.

After that, I’d do whatever decoration I planned and seal the surface for eternity.

This is the most you can do without removing the slab.