Perlite vs Pumice: Pros & Cons of Both in Potting Mix

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The problem with most commercially available potting mixes is that they they don’t drain well, they take too long to dry out, and they simply don’t have enough porosity and air flow to the roots of your plants. Adding perlite or pumice will drastically improve your potting mixes and make a huge difference in the health of your plants.

Keep reading to find out the pros and cons of using perlite vs pumice.

Both perlite and pumice will serve the same purpose, but they have different pros and cons, which I describe below in detail.

First, let’s look at the similarities. Both perlite and pumice:

• Increase the drainage of your potting mixes
• Allow for more oxygen to the root zone of your plants (thus helping to reduce root rot)
• Prevent your soil from compacting
• Don’t really retain much water (unlike vermiculite)
• Are long-lasting and won’t break down (though you can crush perlite with your fingers)
• Are pH neutral
• Are both naturally formed

I almost never use any pre-packaged potting mix as-is because most are not well suited to growing plants indoors. I always mix in additional materials like perlite, pumice and sometimes even other materials.

Let’s take a look at perlite vs pumice and you can make your own decision as far as which one is best for you.

PERLITE VS PUMICE

PERLITE

Perlite is a very lightweight material that is made from expanded volcanic glass.

If you’ve ever purchased a bag of all purpose potting mix, perlite is the material that looks like little styrofoam balls.

In its natural form, it is created when obsidian (volcanic glass) is saturated with water over a long period of time.

After it is mined, it is further processed by man and heated in order to create the perlite that is used in potting mixes. Since it is rich in water, when it is heated to very high temperatures (above 871ºC), it will literally pop like popcorn.

The water will cause the mineral to expand to many times the original volume, anywhere from 4 to 20 times the original volume.

And this is the perlite that we are used to seeing in our potting mixes. Much of the world’s perlite comes from China, Turkey, Greece, USA, Aremenia and Hungary.

PROS

• Cheaper than pumice.
• More readily available than pumice.

CONS

• Tends to float to the top of your soil.
• Can be very dusty, and you’ll want to avoid breathing in particles as it is not good for your lungs. Use a dust mask.

Rinsing Perlite

You can come up with your own ways to rinse but here are a couple good ways:

• Place the perlite in a fine mesh colander and rinse it thoroughly (preferably outdoors).
• You can also make some very small holes at the bottom of your perlite bag, and then run water through your entire bag to keep the dust down before you use it.

Small Grade vs Large Grade Perlite

Keep in mind that if you use a really small perlite (especially one that hasn’t been rinsed to remove the dust), when you mix this your potting mix, it will cause it to take longer to dry out.

There are some advantages to using a larger grade perlite:

• It will tend not to wash out as much out of the drainage holes.
• It doesn’t have nearly as much dust as finer grade perlite.
• Drainage will be better with larger perlite, and your potting mix should dry out a bit quicker.

PUMICE

Unlike perlite, after it is mined, pumice is not processed by heating like perlite is. Mother nature has done all the work.

Pumice is a mined, volcanic rock and is created when super-heated, highly pressurized rock is ejected from a volcano.

When frothy magma cools and depressurizes very quickly, this creates the porous structure found in pumice.

Europe produces the largest amount of pumice. Italy is the largest producer because of all the volcanos, but it is also produced in many other countries including Turkey, Greece, Iceland, Germany, Hungary, and even Chile and many parts of Asia.

PROS

• Will not float to the top of your soil like perlite does
• It is heavier than perlite and better for top-heavy plants, making it less likely for your pot to be tipped over.
• When you use a high quality pumice, you don’t have to worry about breathing in dust like with perlite.

CONS

• More expensive than perlite.
• Not as readily available at stores (but easy to find online).

If you are looking for a great quality pumice, be sure not to miss my post Best Pumice for Succulents: Soil Recipes & Tips to Use where I talk about my absolute favorite pumice that I personally use.