Perlite vs Vermiculite: What’s the Difference?

Ed Wike
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What is Perlite?

Perlite is a hydrous silicate rock. It is formed when high-temperature volcanic lava comes into contact with the ground… such as when volcanic ash cools. As the water vaporizes and expands, the ash is heated and expands, forming a sponge formation. The crystals of the volcanic ash are flattened and interlocked on all sides, causing a larger surface area for contact with moisture. In the commercial world, perlite is known as “volcanic rock.”

It is sold as a lightweight rock, expanded by heat, and obtained in a variety of sizes.

If you’re trying to grow a plant from just a seed, a few small perlite crystals in the soil are great for anchoring the seed to get it started. However, as the plant starts to grow and put on more and more energy, the small perlite crystals will not be able to hold much water, so larger size perlite is used.

The heat produced by the plant will cause the perlite to release moisture and keep up with the plant's needs. Perlite is also useful in soil. It is an awesome tool for helping plants get established. Perlite helps improve drainage and aeration. It can also be used to help buffer a plant's acidity levels to provide a more well-rounded environment.

What is Vermiculite?

Vermiculite is an expandable, mica-like material that is extracted from weathered and altered mica ore. It is predominantly found in the United States, China, Brazil, and South Africa.

It was first introduced into horticulture by a Belgian engineer in the 1930s when seeds of the pines trees being planted in Belgium would not germinate. The engineer recovered the vermiculite from the ore in the mines and discovered that the seeds germinated in the vermiculite. It became an ingredient in plant growing products. However, the vermiculite was not introduced to the U.S. until 1954. The vermiculite and perlite are to be found in a variety of horticultural products that are used to improve soil for specific plants. These products are used for a number of different growing situations.

Vermiculite is highly absorbent and is also stable. It is used for shipping and handling of perlite. It is important to note that vermiculite and perlite perform differently. So combining them in your garden mix requires attention. Vermiculite releases water slowly when it is wet, but it dries quickly. The vermiculite has a pH of 5.5 but is affected by the environment it is used in. It is important to note that it is hydrophilic and is able to absorb large amounts of dissolved nutrients.

More Differences Between Vermiculite and Perlite

Vermiculite is a colorless, botanic mineral also called worm muck.

Vermiculite has been around since the 1940s when it was introduced to replace polystyrene packing peanuts during the time of World War II. This porous, lightweight material is found in nature typically in in the form of mica.

Vermiculite acts as a lattice structure for plant roots and can be easily used in numerous applications such as gardening, landscaping, and potting.

Vermiculite or Perlite Composting Vermiculite and perlite are often used for long-term, outdoor composting. Vermiculite is easy to obtain and can be applied to wood chips and other organic matter used in composting bins or piles. Vermiculite is well-known as a great composting ingredient because of it provides air pockets for bacteria to breed and feed within. Perlite is also an ingredient that is beneficial for composting as it aerates the compost through its many, tiny pores. However, Perlite is less effective than Vermiculite when it comes to retaining water.

In the end, Vermiculite and Perlite both accomplish their jobs well when it comes to composting projects. Experienced gardeners might lean toward the more affordable Vermiculite, while beginners and horticulture enthusiasts might choose the more convenient Perlite.

Which To Use In Your Garden?

Perlite or Vermiculite?

Both vermiculite and perlite can be used in a wide variety of things.

Most people know that vermiculite is an ingredient in potting soil, but they might not realize that it can also be sued as wash water absorbent, to help filter septic systems, to construct radiation shields, to cool supercomputers, and as an ingredient in fireworks, beer, clothing and more.

Perlite is used in a number of different ways as well, such as:

Mulch for plant beds.

A growing medium for hydroponics.

To reduce the temperature of beer.

As insulation for electronics.

As a soil additive.

Vermiculite is a pale or brown cubic mineral, which absorbs water easily and expands up to 15 times it volume when it does so. Perlite is similar, except that it is white and almost twice as lightweight as vermiculite.

If you're planning to use crumbly black garden soil to loosen the soil in your garden beds, you can use either of these products. But if you want to use more uniformed garden soil, which will help the soil retain water and insulate the roots of your plants, you'll need to mix the perlite or vermiculite with potting soil, before you plant.