Perlite vs pumice: Which is best for your plants?

Whether you’re a plant lover with a green thumb or a gardening novice, you probably know how important soil quality is for the growth and health of your plants. But when it comes to choosing the type of soil and additives, things can get confusing. 

In this guide, we’ll compare pumice vs perlite, two commonly used soil additives. This will help you choose the best one for your plants and show you how they can enhance your gardening experience in the long run.

What is perlite used for?

Perlite, technically, is a form of volcanic glass with significant water content. It is processed and expanded through heating to produce a white, lightweight material used for aeration and improving soil drainage. For this reason, it’s a mainstay in potting mixes and a common replacement for peat-containing products, which will soon be banned in the UK. 

What is pumice used for?

Pumice, on the other hand, is another volcanic byproduct characterised by a rough, porous texture. It is often used in horticulture to condition the soil as it offers superior aeration, drainage, and nutrient storage.

Perlite vs pumice for plants: Know the differences

When considering perlite vs pumice for plants and garden maintenance, it’s crucial to understand the key properties that set them apart. These volcanic substances share some similarities in improving soil structure, but they also have unique differences that can significantly influence plant health and growth. 

Below, we will go into the distinct characteristics of perlite and pumice to help you make an informed decision. It doesn’t matter if you’re a complete beginner or a plant expert; you have to know your options.

In terms of texture and weight

Perlite can be regarded as soft and has a sponge-like texture. It helps retain moisture and is gentle on delicate roots, so it’s perfect for seed-starting mixes and plant propagation. 

Pumice, on the other hand, has a coarser and more abrasive texture due to its larger pore spaces. Hence, it’s ideal for improving drainage in denser soils.

When considering weight, perlite is noticeably light and airy, which allows it to float on water. If you face off pumice stone vs perlite, though, the former is heavier and denser. This provides stability within a soil mix.

Aside from the obvious implications of texture and weight, these factors also affect how easy it is to clean your garden. Perlite is often easier to handle and is easier to mix into the soil or remove if needed.

In terms of nutrients

While neither perlite nor pumice adds nutrients to the soil, pumice can hold onto nutrients more because of its pores. This can, in turn, be accessed by plant roots. For perennial plants, it may be a better choice as it can provide long-term nutrient availability. 

Meanwhile, what does perlite do? It also retains a small amount of nutrients due to its porosity. However, due to its light texture, it is more prone to leaching and may need frequent fertiliser applications.

In terms of water retention

Probably the most important question is if perlite holds moisture. The short answer is yes, but it mainly holds water on its surface.

This aids in soil moisture without making it soggy, so it’s typically preferred when growing herbs, and root rot can be a problem. Even better, when mixed with clay soils that are already absorbent, perlite provides much-needed texture.

Pumice, however, can absorb water within its porous structure. This means it can steadily release all the water it contains for plant use. This is especially beneficial for succulents and dry-loving plants.

In terms of aeration and drainage

Both additives promote excellent aeration and drainage. However, due to perlite’s light density, it can become compacted and less useful over time. 

If you're wondering how much perlite do you need to add to the soil, it largely depends on the current state of your soil and the specific needs of your plants. Generally, in a homemade potting mix, perlite is added to the main soil media in equal amounts.

Pumice maintains its structure better so it can continue providing spaces for air and water even with extended use. Hence, it’s a better option for long-term garden soil amendments and can even aid in routine maintenance and garden tidy-ups.

In terms of versatility

Pumice can be more versatile and reused multiple times because of its durability. It also has the ability to slightly adjust pH levels, depending on its limestone content.

On the other hand, how long does perlite last in soil? Well, it tends to break down over time and may need to be replaced in soil or potting mixes. However, its lightness and low cost make it a popular choice for hydroponic systems where plants are not grown in soil.

When it comes to pumice vs perlite for indoor plants, a combination of both is recommended, as each has its own unique benefits and level of flexibility. In terms of landscape gardening, though, pumice is more suited for outdoor applications. 

In terms of cost

On average, perlite is generally more affordable and accessible than pumice. This is because perlite is more widely produced and used in various industries, such as construction and horticulture. 10L bags can run from £5 to £8. There are also larger portions in 100L bags that can cost £30 to £50. For this reason, perlite is often the go-to choice for local garden planters.

Depending on your location, pumice may carry a higher price tag and can be harder to source in gardening centres. For instance, similar 10L bags can cost between £20 and £30 depending on grade and coarseness. 100L bags are often hard to find but can cost upwards of £100. 

Start a garden easily with Airtasker

When it comes to selecting between perlite and pumice for gardening purposes, it’s crucial to consider the specific requirements of your plants and the long-term vitality of your soil. To simplify matters, seek assistance from a gardening specialist through Airtasker. Post a task today and connect with dependable, skilled individuals who can assist you with your gardening needs.