Hydroton vs Perlite: When and How To Use Them (+ 8 Differences)

Hydroton and perlite are two of the widely used growing mediums for gardening. But how can you know which is better for you? Can you use perlite or hydroton for cacti or hydroponics? I use both, but for totally different things.

Hydroton is best to use for hydroponics, while perlite works well in seedling propagation, cutting propagation, and soil gardening. However, perlite can also be used in hydroponics as an amendment. Moreover, they differ in terms of origin and formation, color, size, weight, water-holding capacity, drainage and aeration, types, and cost.

This step of determining which growing medium to use is sometimes what holds gardeners back. So today, I will assist you in making that decision.

Should You Use Hydroton or Perlite? Can You Swap?

Mini hydroton can be used as a topdressing, soil amendment, and hydroponic medium; while, expanded hydroton is better for hydroponics only. Fine perlite is best for germination and cuttings; medium perlite is best used as growing medium amendment for hydroponics, succulents, and orchids; while coarse perlite is best for outdoor and indoor plants.

Here’s a summary of the uses of the different types of hydroton and perlite.

Growing Medium	Grades	Best Uses
Hydroton	Mini	Topdressing for Succulents  Soil Amendment Hydroponics
Hydroton	Expanded	Hydroponics
Perlite	Fine	Starting Seeds Rooting of Cuttings
Perlite	Medium	Hydroponics Succulents Orchids Soil Amendment
Perlite	Coarse	Outdoor Gardens of Herbs and Vegetables Houseplants Soil Amendment

Uses of Hydroton

Mini. This type is commonly used for aesthetic purposes as topdressing. Due to their small particles, they can also serve as a mix for garden soil to increase drainage. They are also good for hydroponic systems with small net pots such as nutrient film technique (NFT) hydroponics.

Expanded. This is best for deep water culture hydroponics, but can also handle plants in NFT.

Uses of Perlite

Fine. This is suitable for root cuttings and for starting small seedlings. This grade can help your garden beds retain more water and drain better.

Medium. Because it is a mix of two grades, it is best used as aeration for potting mediums. Based on my experience, this type is best for succulents, orchids, and hydroponics.

Coarse. This can increase the porosity of your outdoor vegetable and herb gardens. It also performs well as an amendment to growing mediums for indoor houseplants such as calathea and anthurium.

More details are below!

Best Systems & Ways to Use Hydroton and Perlite

Hydroton and perlite are both used in different ways. Hydroton is ideal for hydroponic systems, while perlite is best suited for seed germination, cutting propagation, soil gardening and hydroponic gardening.

3 Systems Compatible With Hydroton

Hydroton is better suited for hydroponic gardening. They perform well in deep water culture hydroponics, nutrient film technique, and ebb and flow systems.

1. Deep Water Culture Hydroponics

Using hydroton in deep water culture takes advantage of its high aeration. This is because the roots are submerged in water for a long period already. Thus, using a growing medium with high water-holding capacity can result in root rot because of an oversupply of water.

2. Nutrient Film Technique Hydroponics

When used as a growing medium in nutrient film technique hydroponics, the heavier weight of hydroton is advantageous. Because NFT uses smaller net cups, you’ll need a heavier growing medium to keep your plant in place.

3. Ebb and Flow Systems

They have a large pore space, which allows for better nutrient solution transport. Because they rarely become clogged or blocked, water drains very efficiently, making it an excellent choice for ebb and flow systems.

4 Ways to Use Perlite

Perlite is a more versatile growing medium as it can also be present in any gardening mix. It can be used for seed germination, cutting propagation, soil gardening and hydroponic gardening.

1. Perlite in Seed Germination

Fine perlite can be used in starting seeds. This is because in the germination process, seeds need more water. This can be provided to the seeds using perlite’s high water-holding capacity.

2. Perlite in Cutting Propagation

The medium air spaces and high water-holding capacity of perlite is advantageous if you are propagating cuttings. Under these conditions, roots will grow faster and better.

3. Perlite in Soil Gardening

In soil gardening, perlite is used as a mix to balance its property of being lightweight. A 20:80 ratio of perlite to other mediums generally works best, regardless of the growing medium. This will work best for your outdoor vegetables and herbs, as well as your indoor houseplants.

For succulents, perlite can be used as a sole medium since succulents are seldomly watered.

4. Perlite in Hydroponics

Perlite can be used as the sole medium for nutrient film technique and deep water culture hydroponics; however, it is still best to mix them with other growing mediums.

The Differences Between Hydroton and Perlite

1. Origin and Formation

Hydroton, also known as lightweight expanded clay aggregate, is formed from the heating of heavy clay until circular porous balls are formed. Perlite, on the other hand, is produced from the seeping of water inside a volcanic rock crystal, obsidian.

As a major contrast, we can observe that hydroton is formed with the application of heat, while perlite is formed with the interference of water.

   Know more about perlite in our article on perlite facts: properties, prices, grades, DIY 

2. Color

Hydroton is usually brown in color, while perlite is white. However, due to the widespread use of hydroton in landscaping, some companies are producing colored versions of hydroton, which include green, yellow, blue, and white.

They are very different in terms of color, as you can see in my videos below! This can also be attributed to the color of the material where these growing mediums are from.

For example, because hydroton is made of clay, they will most likely be the color of clay. The same is true for perlite, which is formed by the rapid cooling of lava or magma and instantly turns white due to moisture.

Fun Fact: Because this process produces small, white particles, they called the product pearlstone, which is now accepted as perlite.

However, both hydroton and perlite also have issues when it comes to their color.

For hydroton…

   Learn more in our article on hydroton turning white. 

For perlite…

   Discover reasons why in our article on perlite changing color. 

3. Size

Hydroton has larger particle sizes, compared to perlite. A particle of hydroton can measure from 3 to 16 millimeters, whereas perlite particle sizes range from <0.5 to 3 millimeters.

I compared these two growing mediums alongside a ruler. My illustration below shows how small perlite particles are! A piece of hydroton ball is even bigger than 5 particles of perlite.

Read further because more details about the particle sizes of hydroton and perlite will be revealed later!

4. Weight

Considered as a lightweight material, a cup of perlite only weighs around 18 grams. This is way lighter than a cup of hydroton which weighs around 58 grams.

You may be asking, “How can knowing hydroton and perlite’s weight help you as a gardener?”

Knowing their weight can help you in management practices. If this is still unclear, consider the following scenario.

Hydroton

• Since hydroton is a heavier growing medium, it is advised not to purchase a bulk (1 sack) of this product if you are just growing in your home. Why? It may incur higher shipping fees.

Perlite

• Because it is lightweight, perlite floats in water. Thus, it is not suggested to use it as a sole medium.
• Perlite can also be blown by air, thus it will not work as a top dressing.
• It is best to mix perlite with garden soil, coco coir or peat moss.

5. Water-Holding Capacity

Perlite has a higher water-holding capacity due to its smaller particle sizes and capillary action principle. Hydroton, on the other hand, have larger particle sizes that create more space. As a result, they do not hold much water.

For you to visualize what I mean, here is an illustration.

Hydroton

Hydroton is not an excellent growing medium in systems that need high water retention. From the figure above, it can be observed that there are more air spaces in hydroton, which have bigger particle sizes.

Important Principle: Larger particle sizes create more air spaces. Therefore, water is not held efficiently and drainage is faster.

(More details on drainage in the next section!)

Perlite

The water-holding capacity of perlite can also be attributed to its capillary action. If you are unfamiliar with this term, here is a real-life scenario to demonstrate.

Have you ever noticed water inside a straw? This is a simple and perfect illustration of capillary action. It is the force that holds the water inside that tiny space.

The factor that perlite and our straw example have in common is a small amount of space. If you go back to the illustration above, you can also observe tiny spaces in between perlite particles. This space traps water on the surface, allowing perlite to hold water for longer than hydroton.

6. Drainage and Aeration

There is faster drainage and more aeration in hydroton than in perlite. This is because it has larger particle sizes.

For this factor, I conducted an experiment to test the water drainage in both growing mediums.

In this simple experiment, I prepared 1) a plastic cup with drainage holes, 2) 1 cup of water, 3) a timer, and 4) the growing mediums (perlite and hydroton).

Hydroton

For hydroton, the drainage time is around 7 seconds only! This means that this growing medium is not suitable for potted plants because the water will simply pass through the roots without being absorbed.

However, in hydroponic systems, where roots are submerged continuously, using hydroton is beneficial because it provides more aeration for the roots.

Considering this, when can you use hydroton? Keep that question because I will answer that in the next sections!

Perlite

For perlite, the drainage time is around 29 seconds. This means, using perlite alone will provide and hold water, but not for that long. This is the reason why in potted plants, perlite is commonly used as a soil amendment—meaning, perlite is added to other growing mediums as a mix.

Furthermore, the medium aeration of perlite is also useful for hydroponic gardening since it balances the air and water needs of the plant’s roots.

   Head to this article to learn more on using perlite.  

7. Types

Hydroton has two types (mini and expanded), whereas perlite has three types (fine, medium, and coarse).

The sizes of each type are summarized in the table below.

Growing Medium	Types	Sizes (in millimeters)
Hydroton	Mini	3 to 5
Hydroton	Expanded	8 to 12
Perlite	Fine	<0.5 to 1
Perlite	Medium	~1
Perlite	Coarse	1 to 3

If you want to know where to use each type of hydroton and perlite, the next section will answer that for you!

8. Cost

In terms of cost, hydroton is more expensive than perlite.

Below are the best products on Amazon for each type of hydroton and perlite along with their prices.

Mini Hydroton. This product comes in different colors if your goal is to elevate the aesthetics of your garden!

Expanded Hydroton. This 1-liter package of hydroton is quite inexpensive given the size.

Fine Perlite. This fine grade perlite is perfect for starting seeds and propagating stem cuttings.

Medium Perlite. Below is a good perlite package on Amazon. It is best for potting soil mixes.

Coarse Perlite. A chunky perlite grade is best for indoor and outdoor plants.

FAQs

When can you exchange hydroton and perlite?

Perlite and hydroton can only be exchanged in the context of hydroponics, as they can both be the sole mediums for deep water culture and nutrient film technique hydroponic systems.

Which is better, hydroton or perlite?

It is determined by the type of gardening being done. For example, hydroton is best for hydroponics, whereas perlite is more versatile because it can be used in soil gardening, cutting propagation, germination, and even hydroponics.

Can you reuse hydroton?

Hydroton can be reused as long as they are disinfected. To do this, one can use hydrogen peroxide, specialized rinsing solutions, distilled white vinegar, and bleach. Learn more about these in our article on how to clean hydroponic clay balls.

Can you reuse perlite?

Since perlite is non biodegradable, it can be reused. To wash perlite, dilute 7 teaspoons of bleach per gallon of water. Soak the perlite overnight and rinse them afterwards. Hydrogen peroxide and vinegar are two other disinfectant options. Explore more in our article on why perlite changes color (can washing help?).

Summary of Hydroton vs Perlite

Hydroton and perlite are different in terms of origin and formation, color, size, weight, water-holding capacity, drainage and aeration, types, uses, and cost.

Hydroton is ideal for hydroponic gardening. Perlite, on the other hand, is a more dynamic growing medium that can be included in any planting mix. It can be used for germinating seeds, propagation of cuttings, soil gardening, and hydroponics.

Sources

• “Inorganic and Synthetic Organic Components of Soilless Culture and Potting Mixes” by Papadopoulos, A.P. et al. in Soilless Culture
• “Effect of Particle Size Distribution of Perlite and its Mixture with Organic Substrates on Cucumber in Hydroponics System” by Samadi, A. in Journal of Agricultural Science and Technology
• “Perlite Gradation and Peat/Perlite Mixtures” by Matkin, O.A. in The Schundler Company
• “Soilless Growing Mediums” by Thakulla, D. et al. in Oklahoma State University
• “The Water-Holding Capacity of Perlite” by Perlite Institute in Hess Perlite