Gardening

What is Perlite? How to Use With Plants & in Your Garden

In this complete guide, we'll give you everything you need to know about using perlite with your plants & in your Garden.
Pinterest LinkedIn Tumblr

So, you’re thinking about starting a vegetable garden this spring – that’s a great idea. Growing food is a fantastic way to cut down on your grocery bill. Fresh, organic vegetables and fruits from your garden are good for your health, providing you with all the nutrients your body needs to thrive.

When making your soil amendments, you’ll need to include perlite into the mix. Open any bag of premix soil, and you’ll notice these tiny white balls mixed in with the soil. They look like polystyrene specks, but we assure you that they are supposed to be in there.

Perlite is a vital component of both gardening and hydroponic growing, and it’s an essential component to add to your soil mix. In this post, we’ll unpack everything you need to know about this mineral.

What is Perlite?

Perlite is a naturally occurring mineral, and it exists in nature as a type of volcanic glass. When water saturates volcanic obsidian glass over time, perlite starts to form.

Humans settled on fertile volcanic lands since the third century BC, and we are aware of perlite, and the role it plays in agriculture.

Natural perlite shows up as grey or black amorphous glass. There is no structure of shape to it, unlike what you see in crystal formations. As with most volcanic rock, perlite is dense and weighty in its native format.

Excavated perlite typically contains the following ingredients.

  • It consists of up to 75% silicon dioxide
  • Aluminum oxide
  • Potassium oxide
  • Iron oxide
  • Calcium oxide
  • Magnesium oxide
  • Sodium oxide
  • Up to 5% Water

Perlite is a non-renewable resource since it’s a naturally occurring mineral. Around the world, there are hotbeds of perlite production, with the most extensive perlite operations being in the United States, Turkey, Greece, and Japan.

Perlite is an inexpensive material, and it has plenty of uses outside of gardening. Many companies use the mineral in the manufacturing of plaster, as well as masonry and ceiling tiles.

However, for this post, we’re going to focus on using perlite in gardening. For us to get the little white balls of perlite we see in our soil mix, we need to use a product that undergoes processing.

Espoma Organic Perlite, From Amazon

How do manufacturers make perlite? Let’s unpack the process in greater detail.

How Do Manufacturers Make Perlite?

The little white balls that you see suspended in your soil mix are essentially “volcanic popcorn.” That’s about the best description we came across for this material. Perlite is mainly water, and when manufacturers heat the material at high temperatures, it “pops” just like popcorn in the microwave.

The manufacturers crush the perlite and then bake it in large ovens at 1,650 degrees Fahrenheit. The heat softens the mineral structure, turning the trapped water inside the perlite into steam and expanding it. As the steam escapes, it causes the expansion of the material, and you have the perlite we use in horticultural applications.

During the heating process, the perlite can expand up to 16-times more than its original size. The tiny white, Styrofoam-looking balls are porous, sterile, and stable after cooling.

What are the Benefits of Gardening with Perlite?

There are plenty of reasons why you should add perlite to your soil mix. The unique chemical and physical properties of the material make it suitable for gardening.

  • Perlite is stable and retains its shape in your soil mix
  • Perlite has a neutral pH, which makes it ideal as a soil amendment
  • Perlite contains no chemicals or nutrients
  • Perlite is a highly porous material
  • Perlite assists gardeners with water retention in the soil while improving drainage

Aerating the Soil and Drainage

Adding perlite to your soil mix provides you with two primary advantages – drainage and aeration. With more air around the roots of your plants, they grow faster and yield more during harvest. Water is another critical component of plant growth, but overwatering your plants will cause the onset of root rot, killing the plant.

Adding perlite to the soil helps to improve the drainage of water away from the roots while leaving the soil with the right amount of moisture to spur growth.

Hoffman Horticultural Perlite, From Amazon

How Do I Use Perlite in My Garden?

There are several uses for perlite around the garden. Follow these tips to make the most out of this material in your flowerbeds and pots.

  • Fortify your soil mix – Add a combination of loam, peat moss, and perlite to enhance the drainage and aeration of your soil, while providing a stable growing medium that absorbs nutrition for your plants.
  • Use it as a surface treatment – Scatter loose perlite over your flowerbed to act as a wicking agent. The perlite will eventually work itself into the soil, improving water retention and draining.
  • Rooting your cuttings – Perlite helps to encourage root growth in new cuttings. Place your cuttings in a Ziploc, along with moistened perlite. The moisture in the perlite keeps the cutting alive while it starts to form new roots.
Mix the perlite in with your soil
Mix the perlite in with your soil

Are there Different Grades of Perlite?

The perlite used in horticultural applications comes in three different grades, depending on the size of the individual grains.

  • Fine Perlite – This perlite is the lightest grade available. It’s suitable for rooting cuttings and starting seeds. You can also scatter this type over your flowerbeds and your lawn to improve water retention and drainage.
  • Medium Grade Perlite – This perlite is the mid-ground between the fine and coarse types. It’s a good choice for potting seedlings.
  • Coarse Perlite – This grade offers your soil superior drainage, and it has the highest porosity of the three types. As a result of the porous nature of the material, it’s a good choice for water retention and aeration in large flowerbeds and pot plants.

Choose the right grade of perlite to match your gardening application. Perlite is affordable and comes in large 40-lb bags. We recommend you order yours in bulk, especially if you do a lot of gardening.

Is Perlite Organic?

Sure, perlite is a carbon-based material; therefore, it is “inorganic.” However, most farmers and gardeners have a different concept of the word as it pertains to their gardening techniques and their crops.

Perlite is not a “synthetic” material, meaning that its natural, and suitable for use in your garden. It’s not a chemical fertilizer, and it contains no harmful compounds. The National Organic Standards Board certifies perlite for use in organic agriculture.

Therefore, if you plan to build an organic farm, perlite is a safe material to add to your soil, allowing you to retain your organic status.

Which Is Better – Vermiculite or Perlite?

Vermiculite is like perlite. It takes the appearance of a golden/black colored material, looking like small chips of bark. However, vermiculite retains much more water than perlite, and it doesn’t offer the same kind of aerating properties as perlite.

If you saturate vermiculite, it may start to rot if you leave it for too long without drying it out. The material becomes mushy and falls apart. Vermiculite is better for increasing water retention in your soil, while perlite is the better choice for improving aeration.

Vermiculite
What Is Vermiculite? How to Use With Plants & in Your Garden

Perlite vs. Diatomaceous Earth

Diatomaceous earth is another sought-after mineral additive in horticulture. This material comes in a fine powder format, and garden centers refer to it as DE. DE is more suitable for pest control than aeration or water retention.

Gardeners can sprinkle DE on plants that are battling with white powdery mildew. DE kills the fungus without the need to use harmful chemicals.

What are the Pros and Cons of Perlite?

Pros

  • Excellent material for improving aeration of the roots
  • An inert and stable structure that doesn’t change the mineral balance or pH of your soil
  • Assist with optimal drainage of the soil, preventing root rot in plants
  • Affordable and readily available for purchase at all garden centers
  • Suitable for gardening and hydroponic systems
  • Helps to improve harvest yields in your veggie crops, and bigger flowers in the garden
  • You use less water in your gardening

Cons

  • The fine-grade vermiculite blows away in the wind
  • Perlite is not suitable for water retention
  • Perlite does not contain any nutrients beneficial for your plants
  • Working with fine perlite requires the use of a respirator to prevent you from breathing it in

Where can I Buy My Perlite?

If you want to get your hands on some perlite right away, order it from your favorite online retailer. However, if you don’t want to wait, then visit your local garden center. Perlite is cheap, and you can pick up a big bag for next to nothing.

We recommend you buy in bulk and then store the rest. You’ll find plenty of uses for it around the garden as the growing season unfolds. It’s hard to overdo it with the perlite, and it’s an excellent soil amendment that’s excellent value for money.

In Closing

Rookie gardeners might not realize the benefits of improving aeration and drainage in your soil. By adding perlite to your soil amendments, you’ll notice a significant difference in your garden’s health this summer.

Perlite is a fantastic soil amendment for improving the growth of your seedlings and plants. Use it as a standalone growth medium for cuttings or work it into your potting mix. Perlite is the secret weapon of successful gardeners all around the world – ad it to your soil today.

1,598 views
Hollie Carter

Hollie is a life-long gardener, having started helping her Dad work on their yard when she was just 5. Since then she has gone on to develop a passion for growing vegetables & fruit in her garden. She has an affinity with nature and loves to share her knowledge gained over a lifetime with readers online. Hollie has written for a number of publications and is now the resident garden blogger here at GardenBeast. Contact her at hollie@gardenbeast.com or follow on twitter https://twitter.com/greenholliec

Write A Comment