Perlite vs Vermiculite: Which to Use and When in Your Eco-Friendly Garden

Perlite vs Vermiculite

If not new to gardening, you must have used an organic fertilizer to amend the soil in your garden. 

But it’s not only nutrients that your plants need to grow. 

Their growth also depends on other qualities of your soil. Texture and the ability to hold moisture and air are just a few.  

Using perlite and vermiculite is one way to help your soil retain moisture and aeration.  

For all those with a perlite vs vermiculite issue on their mind, yes, both of these natural soil additives work in a similar manner. But they’re not interchangeable. There are slight differences in the ways they can improve your soil.

Let’s examine both to establish which  is a better option for your plants.  

Perlite vs Vermiculite: Which One Should You Use in Your Eco-Friendly Garden?

The water-holding capacity is the telltale sign of healthy soil. Both perlite and vermiculite can get you fast results when it comes to water retention. 

And this can cause confusion among gardeners. But what it all boils down to is different amounts of water these materials retain.  

Perlite is good at retaining water but it’s also a porous material that allows for easy water drainage. Vermiculate, though, with its sponge-like surface can hold much more water than perlite.   

So, what do you do when faced with the perlite vs vermiculite dilemma?  

  • You use highly moisture retentive vermiculite to grow your water-loving plants. Such as irises and forget-me-nots. 

    Vermiculite will also be your preferred choice when starting your seeds. The key ingredient for successful seeding is keeping the soil moist and not letting it dry out. This is where vermiculite won’t fail you. 

  • You use perlite to amend the garden soil for plants that prefer well-drained soil. Rhododendrons, cacti, and salvia are a few examples. 

    Substituting perlite for vermiculite is a definite no-no here. Because if you do, you run the risk of your plants developing root rot and dying.   

But there’s much more to uncover about the two soil additives. The sections below will resolve any extra doubts you have.

Perlite vs Vermiculite
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Related: 5 Tips for Improving Your Raised Bed Garden Soil

But What is Perlite Exactly?

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Perlite is a potting medium made by crushing and heating volcanic glass. The volcanic glass expands up to 20 times its original size when exposed to high temperatures (15000 – 16500 F).      

Perlite has a popcorn-like texture. It has a wide, uneven surface area that retains water. However, the minuscule bubbles that make up its structure are filled with air.

What is Perlite Good For? 

Perlite lends itself to many gardening uses as it’s recognized for a number of benefits.  

Here’s the magic that it can do in your organic garden: 

  • Improve drainage. What’s great about perlite is that it retains some moisture but allows excess water to easily drain away. Adding it to your soil mixtures or potting mixes is the fastest way to improve drainage.

  • Improve aeration. Air is just as important to plants as moisture is. But in poorly aerated soil, plants can receive neither water nor oxygen. Perlite addresses this by preventing soil compaction. As a result, your plant roots will be able to respire and allow the beneficial worms to freely fertilize your soil. 

That said, here are a few ideas for using perlite in your gardening projects:

  • Add it to your soil mix. Create your own soil blend by mixing perlite, loam, and peat moss in an equal ratio. It’s an excellent combo for your potting mix as well. Overwatering your plants and soil compaction in your pots can cut off the oxygen supply. In an oxygen-deprived environment tour plants are prone to root rot. Importantly, perlite can stop this from happening.

    Being inert, inorganic, and sterile, it makes for a disease and pest-free growing medium.

  • Use it to start seeds. Perlite is a great growing medium for starting your plants from seeds and root cuttings. Use it standalone or mix it with potting soil to kickstart the growth of your seeds or cuttings.

What is Vermiculite?

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Vermiculite is a hydrated laminar mineral that looks like thin rock pallets glued together. To get the horticultural vermiculite, the mineral is processed with massive heat.  

As a result, it expands and starts behaving like a sponge. 

To get things straight, perlite and vermiculite can both be used to improve moisture retention. But you should know vermiculite holds much more water than perlite. 

And there’s another critical point to consider in the vermiculite vs perlite debate. Vermiculite is less aerating than perlite.  

What Is Vermiculite Good For?

There are many clever ways to use vermiculite in your organic garden. 

It’s ideal for plants that love wet soil. But you’ll also get great results with it if you want to:  

  • Germinate seeds. Although both perlite and vermiculite are good for seed starting, amending your soil with vermiculite will help it retain more moisture. 

    This is critical when starting seeds and growing tiny seedlings. If the soil dries out (which happens easily with soil block and plug trays) your gentle seedlings may wither and die.

  • Grow potted plants with minimal effort. Add vermiculite to your potting soil and you won’t have to worry about watering your plants that often. But that’s not all. Vermiculite can be a great boost for your root growth too. By retaining water it promotes nutrient absorption. And what happens is that your plant roots can grow strong and develop into a lusher plant. 

  • Amend your soil. Plants in your garden beds can also benefit from vermiculite amendments as they boost plant absorption of magnesium, calcium, and potassium. The minerals that are critical for plant growth.

  • Improve your lawn. Vermiculite can help the seeds in your lawn germinate more quickly and fully. Once you’ve done with the seeding, cover your lawn with a quarter-inch of vermiculite. Use 3 cubic feet of vermiculite for every 100 square feet of lawn. Vermiculite used this way will also keep your lawn consistently moist. 

Now, the moisture talk brings us back to our perlite vs. vermiculite dilemma. The best way to clear all doubts as to which one your soil will more greatly benefit from is to test your soil.

Using vermiculite in already moist soil is not the best idea. The opposite goes for perlite. This electronic soil tester can help you get to the bottom of which soil amendment is best to use.

Give Your Soil the Boost It Needs

Has the perlite vs vermiculite dilemma been on your mind for a while? It’s time to finally set it straight. 

Both vermiculite and perlite are great options for you if you want to improve moisture retention of your garden or your potting soil. But to put it simply, it’s about what growing conditions your plants prefer. 

Do they prefer more or less moisture?  

Once you have your answer and have your soil tested for moisture levels, you can act quickly.

Organic gardening can seem like an overwhelming chore sometimes. There’s so much to dig and uncover on an ongoing basis. 

So, whenever in doubt, you can turn to Clean Air Gardening. We’re a leading resource center for everything having to do with organic gardening practices. 

We also offer a good selection of environmentally friendly garden supplies and products.

You can read about our small but dedicated team on online sources such as Inc. Magazine, Entrepreneur, and the New York Times. But also make sure to check us out on our YouTube channel. It’s frequented by over 2000 subscribers and counting.

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