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What is Perlite? A Brief Idea About Perlite Uses in Gardening and Horticulture

what is perlite

What is Perlite?

Perlite is actually a generic term that we use for naturally occurring siliceous amorphic volcanic rock. But unlike other volcanic glasses, if you heat them above a point (8000-9000 C), they expand upto 20 times of its original volume.

What is Perlite Made of?

As Perlite is an amorphic volcanic glass, it is mostly made of silica or SiO2 (about 70-75%). Other than than you will also find a mixture of Aluminum Oxide or Al2O3, and Oxides of Sodium, Potassium, Iron, Magnesium, and Calcium, and moisture.

When heated perlite can expand up to 20 times of its original volume Click To Tweet

How to Make Perlite?

The perlite we use in gardening is not the same as it is found in nature. Perlite is a natural volcanic glass. These tend to have more water in them than other types. Nature’s perlite is grey or black in color and are very dense and heavy.

what is perlite

What we use in growing plants is called expanded perlite. Once the dark grey perlite is heated at a temperature above 850 deg C it becomes soft.

The water that was trapped inside the perlite vaporizes and tries to escape. As a result, the perlite expands more than 10 times their initial size. This expansion of perlite also creates its most distinguishing feature; its unique white color.

Expanded Perlite has many tiny air chambers. These tiny cells that absorb moisture on the exterior of the particle, and prevents it from entering inside. That is why it is particularly useful in providing moisture to plant roots.

This expanded perlite is much lighter in weight and becomes porous in nature. You can crush these with normal pressure. The best part of expanded perlite is it is clean, sterile, lightweight material and doesn’t decay or shrink.

Where Can I Buy Perlite?

Finding perlite should not be a problem for any gardener. They are mined throughout the world. Countries like Greece, the USA, China, and Turkey are the forerunners in this. You can buy perlite at your garden store nearby or you can buy it online. Don’t forget to read the product details thoroughly while buying perlite.


what is perlite

Perlite Uses: What is Perlite Used For?

Because of its low density and low price, perlite has many commercial applications. Among which main uses are building and constructions use, horticultural uses, filters, and filter aids. In gardening and horticulture, perlite is used for a number of reasons.

Apart from gardening perlite is also used in building and construction works Click To Tweet

Advantages of Perlite Soil in Gardening and Horticulture:

  • Perlite encourages quicker germination than any other growing media. You can definitely experience quick seedling growth. It can be used by mixing with peat moss or coconut coir, or used as a potting soil. You can also use perlite solely just  kept wet all the time.
  • Perlite soil is inorganic, inert and sterile. It naturally contains the different minerals which are essential for the growth of the plant. Being inorganic it is free from weeds, diseases, and pests.
  • Perlite is non-toxic and there are very few fire hazards.
  • Unlike peat moss, perlite soil does not decompose very easily (if at all) so you can store and use perlite for many years.
  • It improves aeration and drainage of the soil mix if mixed with other growth media, or soil. Adding perlite is probably the quickest way to increase the drainage of your garden soil. This is particularly helpful in raised beds or in container planting.
  • Perlite is almost pH neutral. So you can use it to reduce the soil-acidity.
Perlite are almost pH neutral. So it doesn't increase the acidity of the soil. Click To Tweet

Disadvantages of Perlite Soil:

There are a couple of disadvantages also of using perlite as growth media.

  • Perlite holds water by having a large surface area and within the nooks and crevices of vast pores. But being porous and made of volcanic glass it allows the excess water to drain away much quicker than any other media. So in case you have really thirsty plants, investing in perlite might not be a good choice.


  • Perlite is a non-renewable resource. So you can not increase its availability as per your likings like that of coconut coir.

Types of Perlite: Coarse Perlite Vs Fine Perlite:

The coarser the perlite better the air porosity. It will be beneficial for your plants in terms of drainage and root growth. This is a very good choice if you are planning to grow orchids or succulents. The main downfall of using coarse perlite is it doesn’t blend well with the soil.

The finer perlite has its own benefits. Its mainly used in creating potting mixes and seed starters. You can mix them with your garden soil to improve its drainage capacity. Know more about potting mix and how to use perlite in potting mix.

Perlite Vs Vermiculite:

One alternative to perlite is vermiculite. Some gardeners prefer to use vermiculite over perlite because of their water retention capacity. Vermiculite generally retains more water than perlite. So it makes them a perfect choice for seed starters. They can also absorb nutrients along with water.

Vermiculite is a very good option if your plants need lots of water. Mixing perlite with vermiculite makes it a more balanced media. Vermiculite absorbs water and nutrients whereas perlite makes sure that the excess water drains away. They are more of a complementary to each other than an alternative.

Read more about vermiculite.

Use of Perlite in Hydroponics:

Perlite uses in hydroponics is very popular nowadays. In case you have never heard about hydroponics, this is a method of growing plants in an enclosed growing space, a controlled environment, and with very little water. As perlite can hold a bit of moisture it is an excellent growing medium under these conditions.

Perlite is used in hydroponics mainly to propagate plants. As roots start to grow in search of a water source, a well-draining media like coarse perlite forces them to grow rapidly. It prevents plant roots against rot.

Other Perlite Uses:

Perlite as an excellent filtering agent. Perlite loose fill insulation is used in the hollow cores of concrete block or cavity type masonry walls.

Besides as a seed starting material in horticulture, Perlite filters are used in many places to filter beer before getting bottled.

Readers Comments (2)

  1. Your posts is quite useful.

  2. Very nice write-up. I certainly appreciate this site.
    Keep writing!

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