Skip to Content

Easily Keep Your Lava Rocks Clean & Looking Nice

Easily Keep Your Lava Rocks Clean & Looking Nice

Lava rock usage in landscaping has seen an explosion in popularity in recent years. Aside from the simple fact that having volcanic rocks in your yard is just plain cool, many benefits come with using them.

They blend in naturally with many types of landscaping, while providing mostly the same benefits as mulch. They won’t break down and nourish your plants, but they’ll last longer than you will!

Additionally, they’re lightweight when compared to other patio stones.

The factor that contributes to nearly all of the beneficial qualities of lava rock is its porosity.

The small spaces and holes in the stone allow it to hold water and air for quite some time. Unfortunately, this can contribute to challenges in keeping the rocks clean over long periods.

They capture dust and dirt much more readily than your average smooth landscaping stone or small grade gravel, but luckily you can clean this with a simple rinsing off. A little attention from the garden hose or a periodic rain can go a long way to keep them looking new.

However, they can quite adept at facilitating the growth of mold, moss, and algae. Anyone with lava rocks has probably experienced this and has been a bit frustrated about cleaning the rocks efficiently — especially without using harsh chemicals or replacing the rocks!

Let’s dive into the easiest ways to keep your lava rocks looking their best, no matter what kind of green stuff is growing on them.

Cleaning Mold

One of the things that you should keep an eye out for is mold on your lava rocks.

If your flower beds are in the shade, often moist, or a combination of the two, mold can quickly grow and thrive on the lava rocks. Mold can be an issue because it can spread to your plants, causing additional problems.

Cleaning mold from your lava rocks can be achieved from increasing sunlight by removing obstacles creating shadow, applying a fungicide, and promoting drainage in the area by eliminating dry spots.

Remove Shadows

Mold loves dark, damp places, so additional sunlight will help moisture evaporate, reduce mold growth, and help kill it. You can trim twigs and branches with loppers.

For thicker branches, a tree trimmer or specialized branch trimming saw will help tremendously and keep you from having to worry about breaking out your ladder.

Apply Fungicide

Liberally spray your moldy rocks with a fungicide. It will kill the mold but won’t harm your vegetation.

You should check the weather beforehand to ensure there aren’t any rainy days for a few days after application, as the solution needs to work for a few days before they can get wet again.

If you would instead use a solution that doesn’t contain chemicals or that you can mix up entirely at home, you can use baking soda and water in a garden sprayer.

Once the rocks have finished drying, move on to the next step.

Eliminate Standing Water

In addition to attracting pests like gnats and mosquitos, standing water also promotes mold growth.

Using a shovel, move the lava rocks out of the bed and set them aside. Next, add a fresh layer of topsoil and spread it out well, so there are no more low spots collecting water.

Replace the rocks and spread them out as you prefer.

Cleaning Moss

While many folks love the look of moss, most probably don’t want it covering up their beautiful lava rocks.

The best way to clean moss from lava rocks is to use a chemical moss controller. When purchasing one, keep an eye out for the following ingredients: copper sulfate, iron sulfate, or ferrous ammonium sulfate.

Simply mix according to package instructions and apply to the mossy area.

Alternatively, a 1:1 mixture of bleach and water can also work, although not as effectively.

Whichever you choose, take care not to spray nearby foliage. If overspray happens, thoroughly wet the area to flush the agent past the root area.

Cleaning Algae

Algae grow where there are excess nutrients, along with high levels of moisture or even standing water. The texture of algae can make it quite challenging to clean, and it will often return if not cleaned properly.

The porous material makes this even more difficult, so doing it right is even more important. Luckily, the approach is simple — much like it is for a bird bath.

To completely clean algae off of your lava rocks, mix a 1:1 ratio of bleach and water into a spray bottle. Spray your lava rocks liberally, but do not spray nearby vegetation.

If you spray nearby plants, rinse the foliage, and flush the soil with 2 to 3 inches of water to move any remaining bleach past the root zone.

Keeping Lava Rocks Clean

Of course, the easiest way to clean your lava rocks is to simply avoid getting them dirty to begin with. As the old adage states, an ounce of prevention is worth a pound of cure.

Thankfully, keeping your lava rocks clean requires only a small bit of routine maintenance!

Here are some steps to follow to keep your lava rocks looking their best.

  • Pull weeds when you first see them. This helps promote sunlight and airflow.
  • Use a leaf blower or similar to remove the fallen leaves and other debris from the rock bed. I have a guide for cleaning leaves out of mulch that should be helpful.
  • Spray the rocks periodically with water to remove dust and dirt. Start with a gentle shower, and wrap up with a focused stream that digs into the crevices and gets the built-up dirt out.

This site uses Akismet to reduce spam. Learn how your comment data is processed. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of, Inc., or its affiliates.