Pumice Vs Lava Rock For Plants – Which One Works Best?

So you are probably wondering – pumice vs lava rock for plants. Should you choose one over the other?

The answer depends on understanding what each option does to your crop, and which one is a better choice.

When gardening, both easily are considered as great potting mixes. They both offer great benefits to the soil’s composition, yet they are very different from each other. Hence, you need to consider these features when making a decision.

Pumice Vs Lava Rock For Plants

If we are looking at the price point, we can easily dismiss pumice as it costs more. Pumice is also not readily available anywhere you go. There are smaller particles in pumice but the porosity level is the same as with a lava rock.

Also, drainage levels are higher with the pumice, as compared to the lava rock. The latter, on the other hand, offers better heat absorption.

Let’s look at these striking differences between the two options:

1. Price – pumice costs more than lava rock

2. Porosity – you can get better porosity from pumice

3. Drainage – Pumice drains better than lava rock

4. Availability – Lava rock is easily available anywhere but pumice has a varied availability.

5. Air Spaces – Pumice floats while lava rock’s floating ability is only moderate

Let us look into these features more below:

Price Point

pumice rock for plants
Pumice rock

Lava rock is widely available, this is why you don’t need to worry about the price point when buying it. The cost is about mid-range or can be low, as well. Just about any gardening supply store should carry this product.

But pumice is not always available, which hikes the price up. You can also find a wider spectrum of choices for pumice due to their porosity feature. Hence, they are pricier since suppliers need to get them from varied locations, which also increases the overall cost.

Porosity And Particle Size

Lava rock and pumice are both porous, yet the latter has more porosity because of the different sizes of pores. You can, however, use either one of them for potting soil because they prevent excess water from getting into your plants’ roots. So, when you have accidentally overwatered the plants, either the pumice or the lava rock will protect the roots from rotting.

As for the particle size, pumice is smaller – almost like sand particles. There are other types of pumice with larger grains, though, which are suitable as a top layering for potted plants.


lava rock
Lava rock

Both of these rocks come in different varieties. But when it comes to drainage, pumice does better, so your plants that have shallow roots can benefit from it more. Lava rock offers medium to high drainage levels. You can expect a decent balance of draining and storing water from lava rock.

Air Spaces

Just one look at a pumice, and you can easily tell it has plenty of air spaces. This is why it is ideal for aeration. Succulents that require high aeration levels can benefit largely from pumice.

But lava rocks don’t have as much air space. Hence, pumice floats and lava rock hardly ever. If you need a substitute for pumice, though, you can use lava rock as it can accommodate various types of plants because of the average air space it has.

Heat Absorption

Lastly, let’s talk about heat absorption. Pumice absorbs minimal heat, in comparison with lava rock. Because of the air spaces in pumice, this makes it not as capable of absorbing heat as lava rock.

But with the darker color of lava rock, this leads to a better absorption rate. So, be careful when using it on plants with a sensitivity to heat, since this may only do more harm than good by damaging the roots.

Which One Should You Choose?

pumice vs lava rock for plants

After learning more about the features of each, you may be wondering – should you go for pumice or lava rock?

The choice depends on the kind of plants you have, what they need to thrive, and your budget.

If your plants require better heat absorption, then choose lava rock. But if they need better drainage, choose pumice.

Also, your budget determines your choice. Pumice is more expensive than lava rock, which can be a bit restricting in terms of what you are comfortable to spend on for an add-on to the potting soil.

Typically, succulents thrive with either pumice or lava rock but not 100 percent of these materials. The water retention is higher with lava rock but pumice offers more trace minerals that can be good for your plants.

You can use either for your plant, yet pumice holds moisture and air better. But at the same time, it is light to the soil, which prevents root damage while protecting plants from infections.

So, be sure to consider what conditions your plants need, so you can make a better decision on which material to get for your potting soil.

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