Perlite vs Pumice – Which is The Better Soil Amendment?

Let’s talk about perlite vs pumice. Both perlite and pumice are great soil amendments, especially for succulents and cacti. However, the question on most gardeners’ minds even the experienced ones is, which is the better soil amendment between the two?

There are some factors to consider that will help determine if perlite is better than pumice and vice versa. So, read on to find out more about these two materials.

Perlite & Pumice

Perlite and pumice are both used to enhance soil aeration and help to reduce waterlogging. They don’t retain water, thereby making them an excellent draining soil material. Potted plants such as succulents and cacti cannot do well with just soil. Their soil needs to be amended with coarse pebble materials to better suit their requirements. Thus, soil amendments like perlite and pumice are used.

First things first, let’s take a look at the characteristics and features of both so we can better understand them. It’s good you understand what they are made of and where they came from so you can decide which is better.

Perlite Features & Uses

Perlite is derived from a mined silicon rock that has been crushed, heated, and expanded. It also contains other minerals like iron oxide, potassium oxide, and sodium oxide.

Perlite is light in weight and color. Before the process of heating, perlite can be brown, red, gray, green, or blue. However, after it has been heated, it becomes light gray or white.

Perlite is commonly used in ceiling tiles, roof insulation, and for plastering. In addition to these household and industrial uses, they are also used in gardening and hydroponics. It is also a great choice for seedling starters as well as root cuttings.

Pumice Features & Uses

Pumice is derived from volcanic eruptions or explosions. It comes from the same type of molten rock that would form granite. Pumice requires much less processing than perlite, so its production is more environmentally friendly.

Pumice is quite soft but not as lightweight as perlite. It is usually referred to as solidified rock foam. Pumice rocks are capable of floating in the water as they contain some air that makes them light enough to float.

Pumice is mostly used for construction and horticulture. Unlike regular concrete blocks, the concrete block that has pumice has a lighter weight and enhanced insulating features. They are used in the garden as soil amendments and they can also be used as a growing medium in hydroponic gardening.

Pumice is especially great for plants that are heavy and predisposed to turning over in the water, as it will keep them rooted in one place.

Perlite Vs Pumice

Let’s compare some features between perlite vs pumice to know our best pick:

• The pumice stone comes in various sizes to suit various requirements and they are lightweight but not as lightweight as perlite.
• Pumice is capable of floating but it is still a little heavier than perlite so it can’t be blown away by wind or storm, unlike perlite.
• Heavy potted plants that are prone to tipping over are better off planted in pumice rather than perlite to keep them steady. Thus, your plants are safe from wind, heavy rain, as well as routine watering.
• Unlike perlite, pumice does not decompose easily. This implies it can last you for a long time without the need for replacement thus, reducing running costs.
• Perlite is not as pricey as pumice. It’s easier to purchase them at your local garden center or nursery.
• Perlite is also easy to access, however, pumice might be expensive in your zone and it might be difficult to get the appropriate sizes that you need. Mostly, bigger sizes of pumice are common. However, smaller sizes may not be always available. The good news is that there are various retailers online where you can obtain the appropriate type and size that you want. All you need to do is to pay a bit for the shipping fee and have your pumice delivered comfortably to your doorstep.

USA Pumice – 1.25 Dry Quarts

Pumice vs Perlite For Indoor Plants

Both pumice and perlite are excellent for improving soil properties such as drainage and water retention. However, pumice has better porosity and therefore offers better drainage potential. But perlite is better at retaining moisture compared to pumice.

Both products are used for different purposes in indoor gardens. Pumice is better suited for tropical plants that need to retain water, while perlite works better for plants like orchids as a soil supplement.

Pumice and perlite will improve the following soil properties when used properly for the appropriate plants;

• soil drainage
• soil aeration

In terms of having particle size options to fit the size of your indoor plant pots or planters, perlite offers more options. Other advantages of perlite include that it is more readily available for purchase, as well as that it is stable and will not disintegrate over time or release any chemicals into the soil. 

Unless you absolutely have to use pumice, we would recommend perlite as our amendment of choice due to the many advantages and choices that it offers.

What is Perlite Made Of?

Perlite is a naturally occurring mineral. It exists as a type of glass in nature, that is formed when volcanic obsidian glass is saturated with water, a process that happens over a long period.

Like all other volcanic rock, it is pretty dense and heavy in its natural form. Typical perlite is made up of the following ingredients; 

• 70-75% silicon dioxide
• Aluminum oxide
• Sodium oxide
• Potassium oxide
• Iron oxide
• Magnesium oxide
• Calcium oxide
• 3-5% Water

Before the use of pumice in plants, it has to be processed into the light stuff that we see, which looks like styrofoam.

What is Pumice Made Of?

Pumice is also a type of volcanic glass. It is very porous and is formed when there are explosive volcanic eruptions. The high porous nature of the pumice is caused by depressurization and rapid cooling after the lava gets ejected from the volcano.

Pumice in its natural form has colors that range from white to dark grey, depending on the place where it is mined. Some gardeners use pumice as a top dress for their soil to give it a more attractive look than just the soil or dirt.

Pumice Or Perlite For Succulents?

Both pumice and perlite can be used for succulents. However succulents like pumice more. This is because pumice absorbs and releases water slowly while helping aerate the roots through the soil at the same time. 

If you are using organic soil to grow your succulents, we would highly recommend that you add some pumice to it, this will greatly help your plants. You can also grow succulents using only pumice, you will however need to be very careful with your watering frequency, as too much may damage your plants.

Pumice is also a bit heavier than perlite. It will work better for top-heavy plants like some succulents by helping to stabilize them. Because it is heavier, it also means that there will be less waste as you will not use much product through wind, rain, and routine watering.

Perlite Vs Pumice: The Option Chosen

Even though the two are great, we still have one clear winner. So, our pick is pumice! Pumice is an excellent option especially in enhancing the soil in your succulent.

Conclusion – Perlite Vs Pumice

Both perlite and pumice are great for soil amendments in your garden. They will both enhance soil aeration and drainage for your succulents, cacti, and other plants.

However, pumice is of greater option because it is long-lasting, doesn’t decompose easily, will hold your heavy plant steady, and so on.  The main downside to pumice is that it’s a bit more pricy than perlite, and not as easily accessible.

All in all, you should go for the one that will suit your needs and plants best.

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