Perlite Vs. Vermiculite: When to Use Each & When NOT to Use Them

When it comes to soil amendments, there are two primary types: perlite and vermiculite. These minerals are often used to improve soil quality, and each has its own unique benefits. Let’s take a closer look at the differences between perlite and vermiculite, and which one might be right for your garden.

Perlite vs Vermiculite: What’s the Difference?

Perlite is a type of volcanic glass that is formed when lava cools quickly. It has a porous, lightweight structure that is similar to pumice. When perlite is added to soil, it helps aerate the roots and improve drainage. Perlite can also help retain water and fertilizers, making it an ideal soil additives for clay.

Vermiculite is a type of mica that is mined from the earth. It has a sponge-like structure that helps it absorb water and nutrients. Vermiculite can also help \with soil compaction, and improve soil aeration and root growth.

What is Perlite?

Perlite is used in horticulture as a soil amendment or alone as a medium for growing plants. When used alone as a growing medium, perlite promotes aeration while simultaneously preventing moisture and nutrient losses due to evaporation.

Perlite also recalls its initial shape and structure after wetting and drying cycles, so it can be reused many times over.

The typical particle size of horticultural perlite ranges from 1/16-inch to 1/8-inch; however, very fine grades (less than 1/32 inch in diameter) are also available.

As with most potting materials, the smaller the particle the greater the number of particles per unit of volume which can translate into better aeration around plant roots but at a reduced drainage rate. Coarser grades (greater than 1/8 inch in diameter) provide better drainage but at the expense of increased aeration.

The physical properties of horticultural grade perlite make it an ideal growing media for greenhouse and hydroponic applications or as a soil amendment. Perlite is a naturally occurring siliceous rock that is widely distributed throughout the world.

When expanded by heat, it is white and lightweight. Its exceptional physical characteristics make it an ideal growing medium.

Perlite has a neutral pH, is sterile, does not provide any nutrition to plants, and provides excellent drainage and aeration while holding a limited amount of water.

Horticultural grade perlite is available in several sizes for different applications. It is important to select the proper size for your needs to ensure optimum performance.

Properly graded horticultural perlite should consist of 85-95% particles that pass through a 2 mm screen with not more than 5% retained on neither any one screen size nor more than 15% passing through any one screen size.


What is Vermiculite?

Vermiculite is a naturally-occurring mineral that has many uses in gardening and agriculture. When used as a soil amendment, it can help to improve drainage and aeration while also providing essential nutrients to plants.

Vermiculite can also be used as a growing medium for starting seeds or propagating cuttings. In addition, it can be used to insulate root systems from extreme temperatures. Whether you’re looking to improve the quality of your garden soil or need a versatile growing medium, vermiculite is an excellent option.

Vermiculite and Square Foot Gardening

Vermiculite is a mineral that is mined and then expanded into light, porous pieces. It is used in a variety of ways, but it is most commonly used as insulation or as a soil amendment.

When used as an amendment, it helps to aerate the soil and retain moisture. It also improves drainage and makes it easier for roots to spread. Vermiculite is often used in conjunction with peat moss to create a lightweight, well-draining potting mix.

Square foot gardening is a planting method that uses square or rectangular beds instead of traditional row planting. This method can be used in small spaces, and it allows gardeners to maximize their yield by planting more densely.

melx mix on tarp

There is a method of creating soil mixtures called Mel’s Mix that is really popular for raised bed and square foot gardening. The mixture includes vermiculite because of its water retention properties.

One advantage of square foot gardening is that it helps to prevent soil erosion. By planting in raised beds, gardeners can reduce the amount of compacted soil around their plants.

This helps the soil retain moisture and prevents rain from washing away nutrients. In addition, square foot gardening can help gardeners to save time and money by using less water and fertilizer.

Common Traits of Perlite Vs. Vermiculite

Perlite is an amorphous volcanic glass that has a relatively high water content. It is a commercially mined volcanic rock found in places such as the United States, Greece, and Japan.

Vermiculite is a mineral that expands when heated, typically forming thin sheets. It is found in many parts of the world, including South Africa, China, and Brazil.

Both perlite and vermiculite have several common traits:

  • Both are very lightweight materials
  • They have a high surface area
  • They are good insulators.
  • Both are used in a variety of industries, including construction, gardening, and horticulture.

While they have some similarities, perlite and vermiculite also have several distinct differences. For instance, perlite is white or gray while vermiculite can be brown, green, or red.

Perlite is also more brittle than vermiculite and has a lower water-holding capacity. As a result of these differences, perlite and vermiculite are used for different purposes in a variety of industries.

Perlite vs. Vermiculite: How and Why to Use Them – Garden Betty

Differences Between Perlite Vs. Vermiculite

Most people are familiar with perlite and vermiculite, but they may not know the difference between the two.

Perlite is a lightweight, volcanic rock that is full of tiny holes. When it is heated, the water inside the rock turns to steam and expands the rock. This expansion makes perlite ideal for use as an amendment or soil-less growing medium because it improves drainage and aeration. Perlite can also be used to insulate plant roots from extreme temperatures. Improving drainage of the soil can help prevent root rot for some potted plants as well.

Vermiculite is also a lightweight, heat-expanded mineral, but it is made from mica instead of volcanic rock.

Vermiculite has a high water-holding capacity, which makes it useful for plants that need lots of moisture. It can also help to improve drainage in heavy soils. Vermiculite can be used on its own or mixed with other amendments to create a custom planting mix.

Which to Use In Your Garden?

If you are new to gardening, you may be wondering what all of the fuss is about when it comes to perlite and vermiculite. These two materials are often used in gardening and can be beneficial for your plants. So, which should you use in your garden?

Uses for Perlite

Perlite is often found in soil mixes and potting soils because it improves aeration and drainage. Remember those two: drainage and aeration.

They are the two things that perlite is super great at.

Because drainage is one of perlite’s specialties, when you’re planting things like succulents or cacti that do not like constantly moist soil, perlite is a great option. Perlite is often thought of as a lightweight sand substitutes.

Uses for Vermiculite

Vermiculite is really good at water retention, so it’s best for seed germination or when you grow water loving plants like tomatoes and lettuce.

Vermiculite acts like a constant watering can for your plants with its moisture retention properties, while making sure they don’t stay too wet. That’s why vermiculite is a favorite in organic gardening and as a potting soil for plants.

Should You Use Perlite or Vermiculite?

So, which should you use in your garden? If you are looking for a material that will help to aerate your soil and improve drainage, perlite is a good option. However, if you are trying to retain moisture in your soil or need a little extra help with nutrient absorption, vermiculite may be a better choice.

If you are going to grow plants in the ground and have clay soil that retains water well, perlite is a great option. If you have compacted soil and need a more well draining soil, vermiculite can help improve the quality. Either way, both amendments can help improve drainage, aeration, and water retention in your soil.

Can You Mix Perlite and Vermiculite?

You can absolutely mix perlite and vermiculite together to use in your soil. This will help with some water retention properties (vermiculite) while also helping drain the soil and improving soil aeration. The combination is usually not necessary for most plants, as they either like well drained soil, or they like consistently moist soil.

But it is definitely doable if you need the soil structure properties of both.

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