What are Hydroton Expanded Clay Pebbles, and How Do They Compare to Other Growing Media

Hydroton clay pebbles are one of the most popular types of growing media. People love them for their many benefits, but they also have a few downsides.

In this blog post, we’ll learn what they are, their benefits and downsides, and how to use them. 

We will also explore alternatives to hydroton pebbles you may want to consider if you’re looking for something different!

What are clay pebbles?

clay in hydroponic system

Hydroton clay pebbles are clay balls that have been expanded to form pebbles. Some people also call it LECA, the scientific name for clay pebbles, and it stands for Light Expanded Clay Aggregate.

So, what are clay pebbles made of?

Clay is formed into small pellets and then kiln-fired at temperatures up to 1200°C. This process causes the clay to expand and create tiny air pockets throughout the clay ball.

These properties make hydroton a versatile growing media and ideal for use as a growing medium or hydroponic substrate. They are also very popular for aquaponics, as they provide a home for beneficial bacteria and can be used to filter water.

Hydroton clay pebbles are available in a variety of sizes, but the most common size is about the same as a grape.

Why do people use clay pebbles? (and why not)

There are many reasons why people use them as a grow medium or substrate. Some of the most popular reasons include:

  • They improve water drainage and aeration through tiny air pockets throughout the clay ball. This is beneficial for a plant because it allows them to take in more oxygen and prevents the roots from sitting in water, which can cause root rot.
  • Expanded clay can be reused over and over again. Simply rinse them off with fresh water after each use and they will be good to go for next time!
  • They are affordable and can be found at most garden stores or online.
  • They help to stabilize pH levels in your grow media or substrate. This is beneficial for plants because it allows them to better absorb nutrients.
  • Clay pebbles are durable and will last a long time. They also don’t decompose, so they won’t add unwanted nutrients to your grow medium or substrate.

What do I need to consider before choosing expanded clay pellets?

transplant seeds in clay

While there are many benefits to using clay pebbles, there are also a few downsides.

Some of the most common complaints include:

  • Clay pebbles can be very messy and can get everywhere if you’re not careful. Using a tarp or something similar when working with them is important to prevent them from getting all over the place.
  • Hydroton pebbles are very light and can float. This can be a problem if you’re using them in hydroponic growing as they may clog up the pumps.
  • They can be challenging to clean because of their tiny pores. If you’re using them in a hydroponic system, it’s important to clean them regularly to prevent them from clogging up the system.
  • Clay pebbles can be difficult to plant in because they are so light. Using a planting tool is essential to ensure your plants stay put.
  • Expanded clay pellets desperately crave continual watering for the roots system to access oxygen from the air surrounding the growing medium. They have a lower water holding capacity than other growing media.

Are clay pebbles better than soil?

This is a difficult question to answer. It really depends on what you’re looking for in a growing medium.

Clay pebbles are a great option if you’re looking for something that will provide good aeration. However, if you’re looking for something that’s easier to plant in and manage, the soil may be a better option.

How to use clay pebbles?

organic expanded clay pebbles

If you’ve decided that clay pebbles are right for your grow operation, there are a few things you need to know about how to use them.

Tip – you must use good quality, not containing heavy metals like arsenic (a known carcinogen). Those toxins will leach into the soil over time when exposed to moisture and cause your plant harm – even if only occasionally!



When using clay pebbles as a grow medium, it’s important to rinse them before planting. This will help remove any excess dust that could harm your plants.

Rinsing is especially true when using aquaponic systems, as hydroton clay is out of the bag covered in red dust. This will prevent more expensive problems and save headaches.


Many gardeners ask if they have to soak clay pebbles before use, and the answer is yes. It’s vital to soak the pebbles in water for at least 6 hours before planting (or even 24 hours). This will help them expand and become more porous, improving water aeration.

It will make the clay heavier and help prevent them from floating away in your hydroponic system.


Clay also compacts more than other mediums, so you must ensure there is enough space for the hydroton clay to expand. They can’t be watered and therefore won’t grow your garden well due to lack of oxygen.

In soil

To plant in clay pebbles, simply create a hole in the grow medium with your finger. Then, insert your plant into the hole and gently press the clay pebbles around the base of the plant. Be sure not to compact the clay too much, as this will prevent proper drainage.

Expanded clay is very absorbent, so it might be best to use a lighter soil mix that drains well. For example, some type of coir (coconut fiber) is not too heavy where the hydroton clay doesn’t have time to drain out!

In hydroponics

In hydroponic systems, simply insert your plants into the net pots and then fill the pots with clay pebbles.


So how often do you water clay pebbles? They need to be watered frequently, as they tend to dry out quickly and have a lower water holding capacity. It’s essential to check the clay pebbles regularly and water as needed.

One way to tell if they need to be watered is to feel them. If they feel dry, they need to be watered. Another way to tell is to look at the plants. If the plants are wilting, they need to be watered.

Tip – Make sure you water them with a light hand. Excess water can cause problems with aeration.


After each use, it’s important to rinse off your clay pebbles. This will help remove any residual nutrients that could harm your plants.

You can also soak your pebbles in a weak bleach solution (one tablespoon of bleach per gallon of water) for a few hours to disinfect them. Be sure to rinse them thoroughly with water before using them again.

What are the best clay pebbles for plants?

versatile growing media

The best clay pebbles for plants are of uniform size and shape. This will help to prevent them from floating or clogging up your system. It’s also vital to ensure the pebbles you choose are free of contaminants such as pesticides or herbicides.

It’s best to buy pebbles from a store with high turnover so that there is less chance of bacteria growth, but if the media are sealed in plastic, this isn’t as much of an issue.

Can you start seeds in expanded clay pellets? 

Yes, expanded clay pellets make an excellent surface for starting seeds. Many gardeners report that it doesn’t dry out as quickly as other materials, such as vermiculite or perlite.

To do so, simply make a small hole in the clay pellet with your finger. Then, insert the seed into the hole and gently press the clay around the seed. Be sure to keep the clay moist but not wet.

Misters set to bursts lasting for four – 10 seconds every two or three hours is your best friend when it comes to seed germination impatiens. Just make sure you soak the expanded clay pellets beforehand. If you do not have misters, manual feeding will also work as long as you do not let clay pellets dry out.

Some growers prefer to crush the pebbles for better drainage. In contrast, others like to sow seeds directly on top of a couple of intact and whole pebbles. 

It’s important to note that not all seeds will germinate in expanded clay pellets. Some plants, such as those that need high humidity to germinate, might not do well.

If you’re unsure whether your plant will do well, start the seedlings in another medium and then transplant them into the clay pellets when they’re a few weeks old.

How do I know how much clay I need?

The amount of clay you’ll need will depend on the size of your system and the plants you’re growing. As a general rule of thumb, one pound of leca clay will cover one square foot to a depth of two inches.

So, if you’re growing small plants that don’t require a lot of space, you won’t need as many pebbles as you would if you were growing larger plants.

If you’re unsure how much you’ll need, it’s best to start with a small amount and add more as needed.

How do expanded clay pebbles compare to other growing mediums?

leca growing media

There’s no one best type of growing media. Many different types of media can be used for growing plants, and each has its own benefits and drawbacks. 


It is one of the most common growing mediums, but it can be heavy and difficult to work with. It also doesn’t hold moisture like other types of media.


Rockwool is another common type of growing medium. It’s made from melted rock that’s been spun into fibers. It holds moisture well and provides good drainage, but it can be challenging to work with and expensive. Compared to expanded clay pellets, Rockwool is more likely to compact and doesn’t allow roots to breathe.


Perlite is a type of volcanic glass that’s been expanded with heat. It’s light and fluffy, and it provides good drainage. Perlite works best for plants that prefer well-draining media or have sensitive plant roots systems. Depending on its intended use, it can be mixed into potting mediums at any percentage you choose.


Vermiculite is a type of mineral that’s been expanded with heat. It holds moisture well and provides good drainage. Compared to expanded clay pellets, vermiculite is used more often as a seed-starting medium because it’s light and easy to work with.

Lava Rock

They’re not quite popular because they don’t hold onto nutrients as readily as clay balls. Still, they are PH neutral and considered a better alternative for plants that like to be more root-bound or those with shallow roots systems. Because it provides air pockets in the potting mix, which increases airflow and drainage.

They are heavier than a pebble, so you will need to ensure your pots have adequate weight capacity if using this growing medium. In addition, they can break when handled too roughly, but this can be remedied by tumbling the rocks before using them.

Sphagnum Peat Moss

Sphagnum peat moss can retain water well and much better than expanded clay pellets. However, it is difficult to rewet once it has dried out and can compact easily. It is also very acidic, so you must be careful when growing plants that prefer neutral or alkaline soils. 


Another excellent alternative is hemp that is lightweight, virtually indestructible, and works well with clay-sensitive plants. It is an excellent alternative because you can also use it as a mulch in your garden to help prevent weeds and retain moisture.

Coco Coir fiber

One of the most popular substitutes is coconut fiber. It’s a more environmentally friendly medium and sustainable option. Still, it also has some downsides – it breaks down quickly in acidic soils (such as pine or citrus) and doesn’t stick to clay-sensitive plants like hemp.


To conclude, LECA clay pebbles are one of the most popular types of growing media, but they’re not the only option. Many different types of media can be used for growing plants, and each has its own benefits and drawbacks.