Perlites: How to Improve Soil Health and Boost Plant Growth

Perlites: How to Improve Soil Health and Boost Plant Growth
External Guest Writer
January 25, 2022

The art of practicing agriculture has slowly transformed into a precise science over the last few decades, thanks to the advent of modern technology. Aspiring farmers and gardeners now have access to a wide range of materials and components that make their job easier than it's ever been in the past. 

Perlite is one such material that has been gaining popularity in the farming and gardening community thanks to its ability to improve soil health and boost plant growth.

In this article, we discuss the nature and composition of this naturally occurring mineral, and how garden perlite for plants can be advantageous in root growth as a potting soil additive.

What is Perlite?

Perlite, also known as expanded pyrite or volcanic popcorn, is a type of amorphous glass derived from volcanoes. It is often confused for other popular lightweight household materials such as styrofoam, but this is a wildly different material in reality.

When examined under a microscope, it is evident that perlite is a highly porous material with plenty of minute cavities on its surface. These cavities allow the glass to hold various nutrients as well as a considerable amount of moisture. As you can imagine, this has immense implications for the world of farming and gardening. 

The nutrients and moisture can be used to help nourish various plants, thereby acting as a perfect substitute for soil and other relevant materials. The best part about perlite is that it is entirely non-toxic, lightweight, and disease-free, making it a material that is extremely easy to work with even for beginners.

We see perlite being extensively used in industrial settings, but it has also become a popular choice for aspiring gardeners around the world. Perlite is also mixed into various products such as ceiling tiles, lightweight plaster, and other masonry elements in order to improve their stability or insulation. 

How is Perlite Made?

Perlite is actually a naturally occurring type of amorphous volcanic glass that is formed when obsidian interacts with water. Thanks to this interaction, this variant of volcanic glass is known to have a higher level of water content than other types of volcanic glass. 

As is the case with most types of materials that are derived from volcanoes, perlites can be found in color schemes ranging from black to grey. It is also extremely heavy and dense in its natural form.

The type of perlite used for gardening, however, is highly lightweight in comparison. This is because normal perlite is heated to create expanded perlite, and this is the type used for gardening and farming purposes. When perlite is heated to the tune of 850 to 900 degrees celsius, it causes the rock to soften and expand dramatically.

When this happens, all the water that’s trapped within the pores of the perlite begins to vaporize and escape from the material. This is one of the reasons why perlite transforms into expanded perlite. The expansion ranges from 7 to 15 times the original dimensions of the material. During this process, even the trapped air within the pores are released from the perlite.

This causes the color to morph into the sparkling white seen in agricultural perlite. This color change is also due to the water in the perlite reflecting light off its surface. Thus we see that perlite transforms into a new version of itself known as expanded perlite. This is a lighter version of the original form and has a greater number of cavities in order to successfully hold more nutrition and water. 

This new perlite is also quite malleable and it can even be crushed with the application of a moderate amount of pressure. However, it does not succumb to the light pressure of soil, nor does it shrink or decay. Additionally, it is also extremely sterile and clean in its new form.

Expanded perlite consists of 70-75% silicon dioxide. Some of the other chemicals found in this material include:

  • Calcium oxide
  • Magnesium oxide
  • Iron oxide
  • Sodium oxide
  • Potassium oxide
  • Aluminum oxide

Perlite also falls anywhere between 6.6 to 7.5 on the pH scale. Moistened perlite is typically mixed in with potting soil to provide good aeration for plant roots, and as a loose fill insulation.

What Are the Main Uses of Perlite?

There are two main reasons one should consider using horticultural perlite for agricultural or gardening purposes. We discuss these reasons below.

Improved Drainage

Perlite is considered to be one of the best natural filtration systems currently available in the market. It allows all the excess water in your plantation to drain away naturally, but it also captures the right volume of moisture and nutrients in order to nourish the plants. 

The advantages of perlite are especially evident when used in container gardens and raised beds, but they can be just as effective in the ground as well.

Improved Airflow

When perlite is added to the soil, it helps to drastically improve the airflow in the plantation beds. This helps the plants by allowing their roots to breathe with greater ease. It also assists the microcosm living in the soil, helping organisms such as nematodes and worms to access the necessary levels of oxygen.

As the natural composition of perlite is tougher than soil, it also prevents compaction of the ground near the plants, thereby allowing the soil to remain lightweight for longer periods.

How to Use Perlite?

There are two types of perlite currently available in the market, and both these variants can be used differently based on a person’s individual needs. These types are known as:

  • Coarse perlite
  • Fine grade perlite

Coarse perlite is known to be the most porous version of this material, which is why it offers improved drainage capabilities. It also helps to boost the airflow in the soil and improves the breathability of the embedding material. 

Coarse perlite is specifically sought after by individuals who are growing succulents and orchids as it greatly compliments the needs of these plants. It is also best suited for container gardening techniques.

Fine perlite, however, is much better at working its way to the surface of the soil blend. This is a double-edged sword, as the fine particles also risk being blown away or washed away by heavy wind or rain.

Fine perlite is best suited for seed-starting mixed or for rooting cuttings. This is because the drainage capabilities of the fine glass can help to boost rapid root production, similarly to peat moss. One can also utilize perlite by scattering it over the surface of the lawn and allowing natural processes to move the material into the soil in order to improve drainage.

Perlites in Hydroponics

Hydroponics is the practice of growing plants without the use of natural potting soil, and it is easy to imagine why perlites can be useful in this process. It works best when applied to the technique of propagating plants with their cuttings using high to medium grade perlite.

Organic hydroponic gardeners prefer to use perlite over other forms of rooting mediums as perlite does not contain any additives or toxic chemicals, and is ideal for water retention with a decreased risk of root rot.

When the roots of a new plant begin to stretch outwards in search of a reliable water source, using perlite can encourage it to grow rapidly. The roots are encouraged by the fact that the perlite contains important pockets of moisture and nutrition, and this boosts their growth in an impressive manner.

The Might of Perlite

It is hard to imagine that a type of volcanic glass that is naturally occurring on our planet could have such immense applications in the field of agriculture. This is the wonderful world we currently live in, a world where technology and information move hand in hand to help improve every process imaginable. If you have a garden or plantation, make sure to utilize this versatile compound to help boost your soil health and easily nourish your plants.