Pumice vs Lava Rock (What to Pick for Your Gardening Needs)

When it comes to gardening, both pumice and lava rock play a crucial role in making potting mixes. Each adds its own unique flavor to the composition of the soil. But, their similarities and differences can make it confusing to choose.

So, indeed, which one should you pick in Pumice vs Lava Rock?

In terms of price and availability, pumice is more expensive and harder to get than lava rock. Pumice also has smaller particles however, both are more or less the same in terms of porosity. Lastly, pumice has higher drainage and drainage but lava rock has greater heat absorption.  

Regardless, these aren’t the only distinctions. That’s why we’ve broken down this topic for you in simple terms.

Let’s hop in the wagon and go exploring!

Pumice vs Lava Rock: The Basic Comparison

pumice vs lava rock

 Keep in mind, while gardening you will come across both at a certain point.  Before we head on to a thorough comparison, we should know the basic differences. 

To make things easier for you, we have a small table for you below. Follow along to see what’s happening.

FeaturesPumiceLava Rock
PriceRelatively expensiveMid-range
AvailabilityVaries Always available
Particle sizeSmall Large
PorosityHigh Moderate to high
Air spacesVery high, can floatModerate
DrainageHigh Medium to high
Heat AbsorptionLow High

You should have a general idea about this topic by now. Have you made your mind up about which one is better? 

Pumice vs Lava Rock: Detailed Comparisons

We know that the aforementioned points are insufficient to reach a conclusion on the subject. That’s why we’ve spent so much time talking about them.

Again keep in mind, which one you’ll choose depends on you. It will also depend on the type of plant that you want to grow. 

1. Price & Availability

The availability is partly the reason why the prices are different. Since lava rock is readily available, they are priced from low to mid-range values. You can find them across gardening supply shops as well as online. 

Since pumice isn’t so readily available, it tends to be pricier. Pumice has a larger spectrum of options based on their porosity.  These tend to be pricier because they are outsourced from different locations and the transportation costs add up.

2. Particle Size

Pumice has a small particle size. Some pumice has sand-like particles while other pumice types have larger grains. This makes them great as a top layer for your potted plants.

Lava rock on the other hand has larger particles. They allow gaps to be made inside the soil which allows roots to grow. So if you’re dealing with indoor plants or potted plants, you might want to opt for lava rocks as a soil additive.  

3. Porosity

Both pumice and lava rock have similar porosities. Some argue that the porosity of pumice is slightly greater than lava rock due to many uniform pores.

Both are great additions to your potting soil because they act as barriers to excess water. If mistakenly, you overwater your plants, this will keep your roots from spoiling. They do this by storing the excess water in these pores.

4. Air Spaces

Pumice has a lot of air spaces. This makes it great for aeration. Especially for plants like succulents that need aeration and room to catch moisture.

Lava rocks have fewer air spaces than pumice. It’s why pumice floats while lava rock doesn’t. But they still have enough to be a great alternative for pumice. The lava rocks also have a wider variety of plants to accommodate because of their moderate air spaces.

5. Drainage

Keep in mind, both rocks have a spectrum of variety. However, pumice has better drainage than lava rock. This makes them ideal for plants with shallow roots.

Lava rock has moderate to high drainage. They maintain a good balance between storing and draining water. This makes them ideal for use with different types of plants. 

6. Heat Absorption And Release 

Pumice tends to absorb less heat than lava rock. This is because of the large number of air spaces it has. Air is a good insulator, which is why pumice has low heat absorption and release.

Lava rock, being darker, absorbs and releases more heat. This can damage the roots of the plants, especially if they are sensitive to heat.

Final Decision: Which to Choose Between Pumice Vs Lava Rock?

Have you made up your mind on which one you’ll go with?  Even after all of this, you could remain perplexed. But don’t be concerned! We can clear up your doubt.

Simply put, if you have the budget and plants that don’t need really high drainage, use the lava rock. It has a wide array of uses and the costs are manageable. However, if you have specific plants that need better drainage like cacti or bonsai, pumice is the way to go.

This is where it all boils down to.  

If you ask us, we will pick the lava rock. Simply because it’s more widely available and makes for a great and affordable soil additive.

However, if you’re a low-maintenance or indoor gardener, you may opt for succulents and other related plants. To keep these plants healthy and drained, you might want to pick pumice. 

Frequently Asked Questions

Question: Is pumice the same as lava rock?

Answer: While they are both volcanic rocks, they are not the same. The easiest way to distinguish them is by color. Pumice is usually white or cream in color. Whereas lava rock tends to be red or black in color.

Question: Is pumice toxic?

Answer: No. Pumice is not toxic. By nature, it is a neutral material. Because of this, it’s non-toxic and non-hazardous. 

Question:  Does lava rock hold water?

Answer: Yes. Lava rocks hold water. This is because when the lava cools, it cools upon contact with water and air. So it forms these pockets that can hold water. 


And that’s a wrap. We hope you are completely clear between Pumice vs Lava Rock. You may now choose whatever option best matches your needs.  

So, which one will you choose? Let us know what you think in the comments!

3 thoughts on “Pumice vs Lava Rock (What to Pick for Your Gardening Needs)”

  1. Pingback: Does Pumice Absorb Water?

  2. Pingback: Blu-lock vs Eco-lock (Sprinkler Fittings Compared)

  3. What type of rocks can I use on my out door plants and rose bushes that are in wine barrels to keep squirrels from digging into the soil?
    Antioch California

Leave a Comment

Your email address will not be published. Required fields are marked *