Perlite Vs Vermiculite: What Is It And How To Know The Difference

If you happen to be at a garden center trying to decide what will better suit your plants? Well, vermiculite and perlite are quite similar, which is usually why people think about this. However, some key differences help you put things into perspective where the two are concerned.

Apart from just knowing how to contrast perlite and vermiculite, you also need to create the best environment for your garden plants. Water and nutrients are essentials in growing garden plants, as is soil aeration.

However, not all garden soil environments have these elements as much as they’re needed. If your garden is one of them, you may want to start thinking about perlite or vermiculite.

Today, we are here to tell you all about the two. By the time we’re done, you will be educating others about whether they should choose perlite or vermiculite, based on their plant growth needs!

What Is Perlite?

what is Perlite

Perlite is a compound made from volcanic rock. It has the nickname “volcanic popcorn,” based on the fact that it’s created when the said volcanic glass is heated enough to expand and pop.

The result is a highly porous, white, lightweight rock. From a distance, we wouldn’t hold it against you if you thought you were looking at a collection of Styrofoam balls. On that note, it would be best if you didn’t use styrofoam as a stand-in for perlite.

Pelite is relatively high in water content, therefore when heated to at least 1500F it will cause the water content in this rock to evaporate. Thanks to a cavern-like texture, you’d be hard-pressed to find a similar material that sheds water with the kind of effectiveness of perlite. Vermiculite doesn’t shed water like perlite does and is instead a better holding agent. 

The impressive thing about perlite is that while it may not hold water, it can help to a small degree to hold minerals for your plants.

It may be confusing to hear that perlite doesn’t retain water but can still retain plant nutrients. These two capabilities feed into why perlite is hailed as healthy compound drainage for soil.

Perlite use improves the soil structure and does an amazing job of getting the required oxygen to plant roots.

What Is Vermiculite?

what is Vermiculite

Like perlite, vermiculite is naturally occurring, and it expands when it is heated. Vermiculite is a name given to hydrated phyllosilicates (elements with an aluminum-iron magnesium composition) with a shiny aesthetic that is sometimes grayish-brown and sometimes silvery-gold.

The heating process causes the mineral to expand greatly to many times its volume. The result is that the once flaky mineral takes on a pebble-like appearance.

The material processing continues to yield the fine, medium, and coarse vermiculite grades you may see in garden use. The material is sterile, lightweight, non-toxic, mostly non-reactive to acids, and is safe for many uses.

If you need a compound that holds water well, we’d say you should check out vermiculite. Perlite may shed water better, but it has nothing on vermiculite in the moisture retention space.

Vermiculite was said to contain asbestos fibers, but this was nothing more than a rumor. However, it is important to note that there was once a time when asbestos was present in vermiculite. You may even still find it in attic insulation of older homes.

The past asbestos problem existed between 1919 and 1990. The source was a mine in Libby, Montana, that supplied approximately 70% of commercial vermiculite needs.

The vermiculite deposits, which was sold under the brand name Zonolite, contained naturally-occurring asbestos. This was the tremolite-actinolite variation.

Note, however, that once the asbestos was discovered, the mine was shut down. So, if anyone tells you that asbestos is present in today’s Vermiculite, that person has some research to do.

What Is the Difference Between Perlite and Vermiculite?

If vermiculite and perlite both have similar uses in the garden, how does a plant benefit from your choice of one over the other?

The real difference lies in the water retention capabilities of each medium. Looking at things from the perspective of how well each holds moisture helps you decide which one should be used for your gardening needs.

If your gardening efforts involve plants with a high water requirement, you may want to implement vermiculite in your soil mix. If you opt to use perlite in such contexts, you’re going to be disappointed because the soil will dry out.

On the flip side, plants that thrive in dry conditions will not benefit from your using vermiculite. There’s just too much moisture in the medium, which may create issues for your plants, such as root rot.

The worst-case scenario is that you end up seeing your plant die instead of seeing them grow.

Frequently Asked Vermiculite and Perlite Questions

With the gardening tips we  gave you above, you should have no problem starting with perlite and vermiculite. If you want to improve your soil conditions, so that seed can grow, it warrants knowing which medium to use in which context.

However, people tend to have common questions about the two as they consider implementing them in their potting mix.

So, here are some answers to the questions, which should put concerns about your soil drainage capability and soil aeration needs to rest.

Is Vermiculite or Perlite Better?

From an objective standpoint, we can’t cite perlite or vermiculite as better for your potting mix soil.

You’re going to have to consider the moisture requirements of whatever seed you’ve planted, which will help you grow your plant effectively with one of these two compounds.

Perlite is excellent if you want something to loosen heavy soil, which can improve drainage in your flower beds. So, for plants that need little water to thrive, you don’t want a material that has great moisture retention.

The increase in air flow, when using perlite, makes it easy for oxygen to reach to the plant roots.

Vice versa, vermiculite can increase soil compaction and reduces the oxygenation capability of soil 

However, if you need is for better water-holding, then vermiculite is the better alternative. If you notice that your soil drains much too quickly in the seed starting process, you need a compound that can better retain water.

Vermiculite acts as a superb holding agent in potting mixes. we would even go as far as saying it’s like a sponge.

Perlite Vs Vermiculite: Can You Substitute One for the Other in Your Potting Soil?

The only way you can substitute perlite for vermiculite and vice versa is if your potting soil aeration and drainage capabilities don’t have much bearing on the plants’ ability to grow. 

Some plants can thrive well in almost any context, even if clay soil is in the mix.

You probably don’t even need to mess with the potting soil mix in such instances since you don’t need the soil to stay moist or dry. Still, you could use either medium.

Note, however, that your gardening efforts are very unlikely to have such a context. For example, if you can’t access anything but clay soil, you likely want to modify its water retention properties.

Perlite and vermiculite tend to be used to either make potting soil drain water more or less effectively. In either case, the plants in the garden have unique requirements. Hence, you can’t substitute one material for the other.

What Are the Pros and Cons of Perlite?

Perlite could potentially become a fundamental part of your gardening needs. If so, we think it’s a good idea for you to understand how the benefits we’ve already highlighted stack up against the potential drawbacks. 

Let’s address the upsides first:

  • The drainage and aeration properties are top-tier, and the loosening effect can extend to a respectable soil surface area.
  • Perlite has an incredibly stable structure. One consideration you may have when adding a foreign compound to your potting mix is the potential negative effect it could have on the said soil. If the potting soil integrity becomes compromised, you end up with one of the most dangerous potting mixes ever. However, perlite brings tremendous stability to the equation.
  • A neutral pH level is an innate property of perlite. A pH level that strikes the right balance between alkaline and acidic is great for seed starting mixes in your gardening.
  • You can opt to use perlite as the perfect lightweight alternative to sand.
  • The composition of perlite makes it resistant to rot or mold, which means you can use it to improve your potting mix for a long time to come. 
  • You get a clean, sterile, non-toxic, and odorless compound when you opt for perlite.
  • Perlite can hold nutrients and up to four times its weight in water, making it one of the most powerful soil additive.

That’s a lot to be happy about, right? We thought so too. Compared to the downsides, we would say that’s a laundry list.

Let’s have a look at the drawbacks:

  • There are different perlite grades, and if you are working with a fine one, airflow can throw it off very easily if the said airflow is too strong.
  • If you’re interested in growing tropical plants, you may want to choose something other than perlite, as they need potting soil that can retain water better.
  • Since it’s made from volcanic glass, perlite does not break down.

What Are the Pros and Cons of Vermiculite?

You could just as easily choose to use vermiculite for your gardening needs, especially if you don’t need water to drain too quickly.

Like perlite, vermiculite also has its list of ups and downs to consider before choosing to plant your flowers with it in the mix. 

Let’s start things off with the upsides:

  • Vermiculite and peat moss can retain moisture, which means plants that require more moisture can enjoy an environment conducive to growing them in your garden.
  • As with perlite, you can use vermiculite to great effect for seed starting or if you’re interested in blending custom potting mixes.
  • If you have heavy and compacted potting soil types on your hands, vermiculite is the perfect ingredient to loosen it, making flower beds more suitable for growing plants.
  • Plants that require a lot of moisture can enjoy high retention of nutrients just as they can more water.
  • Your potting mix creation process should be a breeze, as vermiculite mixes incredibly well with soil. The mixing process also tends to be very straightforward in execution.
  • Vermiculite isn’t toxic. It’s sterile, clean, and has no smell.

Don’t expect all roses with vermiculite either, as there are a few downsides that warrant healthy discussion.

Here are the downsides:

  • Though you’d need way too much water to see root rot take shape, vermiculite’s lack of sufficient drainage can create an issue in a garden, even for plants that need more water than others. Remember, it’s like a sponge, so you must understand how to use vermiculite for your plants in gardening.
  • Vermiculite can be highly alkaline reactive. Therefore, plant roots can get damaged from a pH raise.
  • Since vermiculite is not the most effective element at keeping things dry, it can create an environment conducive to bacteria and fungi that prefer to live in more moist environments.
  • Vermiculite also doesn’t break down based on its composition.

What Are the Fundamental Reasons to Use Perlite Vs Vermiculite?

So, with all we’ve said up to this point, can you identify when you use perlite vs vermiculite? You probably can, but let me just go over a few of the main use cases for the two.

You’d opt for perlite in the following cases:

  • Loosening heavy soil types in your gardening, such as clay soil. This is especially true when you want the said soil to stay in its new form since the volcanic rock doesn’t break down.
  • You’re repotting house plants that need more aeration and drainage, as water retention is not healthy for them. For these plants, such as cacti and succulents, your best bet is to ensure that your potting mix has the right amount of perlite granules in it.
  • If your gardening is done in a wet or humid climate, it has implications on your garden bed soil. With its low water retention capabilities, Perlite helps the soil from ending up in a waterlogged state.

Consider vermiculite in the following cases:

  • You’re just beginning to start seeds in your garden soil. Vermiculite holds water incredibly well. The last thing seeds in your garden need during seed germination is intense soil drainage. Should the seeds dry out during that time, your gardening efforts would have been wasted.
  • You’re repotting plants that fall under the outdoor container or garden beds category. Once you’re putting plants outside, there’s an immediate difference in soil hydration. They’re even less likely to retain moisture if their designated potting medium is porous. Vermiculite acts as the perfect fix to the problem, thanks to its fantastic water-holding capacity.

In the perlite and vermiculite contest, you use perlite when soil drainage is more important. You use vermiculite when you need to retain more moisture in your soil.


Perlite and vermiculite are superb elements to add to your soil for different soil amendements reasons. While there’s a huge difference in what the two can do for you, they both have their place in your garden.

That’s why we’d never put perlite vs vermiculite and say one is better for the soil than the other.

We would need to know the context of the soil first. If it needs to be dry, then we’d suggest perlite, whereas if moisture is important, we’d suggest vermiculite.

Here’s a fun fact for you. You could even mix the two and get the best of both worlds! Just be careful in handling them, though.

While they are not toxic, long-term exposure could make your lungs more susceptible to respiratory issues in the future.

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Daniel Buckner is an indoor gardening enthusiast and hydroponic expert with years of experience cultivating a variety of plants. Passionate about sustainable living and urban gardening, Daniel shares his knowledge through engaging content to inspire and educate fellow gardeners. Discover the joys of indoor gardening with Daniel's practical tips and valuable insights.

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