You know that growing hydroponically involves no soil – which is why so many growers refer to this style as a “soilless” method of cultivation. However, the vast majority of systems still rely on something to anchor the roots and hold your plants in place. This is known as the hydroponic medium in your system.

Wait – what’s a hydroponic medium, exactly?

Don’t worry – in this complete guide we’ll cover everything you need to know about hydroponic growing medium.

Also known as hydroponic media, there are many different types to choose from – Rockwool, clay pebbles, coco coir, and many others.

While each of these types has its unique pros and cons, it’s important that you choose the right media for your plant type, system style, and growing preferences. We’ll cover all this and more throughout our discussion today – and towards the end, we’ll explain which growing media we feel is best.

First things first – let’s explain what hydroponic grow medium is and what separates it from traditional soil.

What is Hydroponic Growing Medium?

Just because you’re not growing in soil doesn’t mean your plant is going to sit in an empty net pot – you still need something to hold it in place and support the roots! That’s where your hydroponic growing medium comes in.

The term “medium” is used to define what you grow your plants in. Soil is a type of medium, too – but hydroponic mediums are in a class of its own.  his can be any inert substance that can be used to support plant roots. What does “inert mean”, though?

This is important – because it’s what separates hydroponic media from traditional soil. Unlike soil, this type of media doesn’t provide any essential nutrients. Rather, it’s simply there to serve as an anchor for the roots.

This is part of why hydroponics growers prefer this method – you are essentially working with a “blank slate” nutritionally speaking. All the plant’s nutrients come directly from what you feed in the reservoir.

What’s interesting is that while you can’t really grow hydroponic plants with soil (by definition), you can technically grow traditional potted plants with a hydroponic medium – like coco coir. In fact, many growers prefer growing in pots with coco for this exact reason.

Most potting soil contains nutrients – which is great for plants with low nutritional needs because then you may not need to feed bottle nutrients.

But for plants like cannabis, nutritional needs are high. Trying to balance your bottled nutrients with the nutrients already present in the soil can be a challenge. If you don’t get the dosage right, you could end up with nutrient lockout or nutrient toxicity.

That’s a discussion for another day, though. For now – let’s talk about a common misconception. Is there a difference between media vs medium?

What is the Difference Between Hydroponic Media and Medium?

Now that we know what a hydroponic growing media is, you might be wondering – what’s the difference between media vs medium? In short, no – there isn’t a difference. They both refer to the same thing.

The term “hydroponic media” is just another way of saying “hydroponic medium”. It’s more common to hear people say “media”, but they’re interchangeable. For the rest of this guide, we’ll use the terms interchangeably. Ready to learn about the different types of hydroponic grow medium you can choose from? We’ll break down each of them below in-depth for you.

With that out of the way – let’s talk about why it’s so important to carefully consider which hydroponic growing medium you choose for your plants.

The Different Hydroponic Mediums Explained

As we briefly touched on earlier – there are many different types of hydroponic media to choose from. They all have their own unique pros and cons, so it’s important that you understand what each type offers before making your decision. Below, we’ll explain the most popular types of hydroponic media in-depth.

Clay Pebbles

First, we’re going to talk all about using clay pebbles in hydroponic gardening. This inert hydroponic growing medium is also known as hydroton. It’s made by heating clay to well over 2,000 degrees Fahrenheit. This leads to air bubbles forming in the clay. This porosity leads to an incredible balance of aeration and water retention. 

We love growing in clay pebbles for a few reasons. One, the drainage they offer is excellent – as we just mentioned. Proper drainage allows for oxygenation – which in turn, leads to supercharged nutrient uptake. But that’s not all. They are very long-lasting. You can use them grow cycle after grow cycle – just give them a good cleaning and they’re ready to be put right back to the test. This makes them a more sustainable choice than other styles. Moreover, clay pebbles are pH neutral which allows for easy nutrient optimization.


Rockwool is made from melted rock that’s been spun into fibers and looks a lot like fiberglass insulation material. Because it’s derived from natural materials, it’s considered eco-friendly and safe for use with food crops. Rockwool is also one of the most popular types of hydroponic growing mediums because it holds a lot of water while still allowing roots to breathe.

One downside of rockwool is that it can be irritating to the skin and eyes. It’s important to wear gloves and a mask when working with it. Another potential downside is that it can harbor harmful bacteria if not properly sanitized – which is why we only recommend using new, sterile rockwool cubes or sheets.

Coco Coir

Coco coir is made from the fibers of coconut husks. It’s an eco-friendly hydroponic growing media because it would otherwise go to waste – coconuts are harvested for their meat and water, not the husk! Coco coir has excellent drainage and aeration properties, and it’s also resistant to pests and diseases. Many growers prefer using coco coir because it can be used again and again – as long as you properly sanitize it between uses.

The main downside of coco coir is that it doesn’t hold nutrients well, so you’ll need to feed your plants more frequently than if you were using a different type of medium. And, coco can really suck the calcium out of your plants.


Perlite is made from volcanic glass that has been heated until it pops like popcorn. It’s a very lightweight hydroponic growing media with good drainage and aeration properties. And, you’ve probably seen it in other types of media, like coco coir or rockwool. It’s the tiny white specs. So, why is it used in these other media? To create the perfect balance of drainage and water retention.

The main downside of perlite is that it can be dusty, so it’s important to wear a mask when working with it. You should also avoid inhaling the dust, as it can be harmful to your lungs.

Peat Moss

Peat moss is made from decomposed organic matter – usually plant material like Sphagnum moss. It has good water-retention properties and is often used in conjunction with other types of media to create the perfect balance of drainage and water retention. Peat moss is also resistant to pests and diseases, which makes it a popular choice for many growers.

The main downside of peat moss is that it can be difficult to find in stores. You might be able to find it at a gardening center or online, but its can be tricky to track down.


Vermiculite looks similar to perlite, but it’s darker in color and has a slightly spongy texture. is made from a type of rock that’s been heated until it expands like popcorn. Vermiculite holds nutrients and moisture well, which makes it popular among growers.

The main downside of vermiculite is that it can be dusty, so it’s important to wear a mask when working with it – just like with perlite. You should also avoid inhaling the dust, as it can be harmful to your lungs.

Why The Type of Hydroponic Growing Medium You Choose is so Important

Not all hydroponic growing medium is created equal.  In fact, the type of medium you choose can make or break your entire operation. That’s why it’s so important to do your research and choose the right one for your needs.

The most important thing to consider when choosing a hydroponic medium is the balance of water retention to aeration offered. Your plants’ roots need access to two things in your hydroponic system: the nutrient solution and oxygen. Each of the grow media we discussed above offers a varying balance between these two – as you have to compromise on one to satisfy the others.

If you go with a hydroponic grow medium that offers great water retention but no aeration, your roots will suffocate – and you could also develop root rot problems. On the other hand, a hydroponic growing media that offers great aeration may lack water retention – and will lead to your root mass drying out too soon. The best hydroponic medium offers a great balance between these two – more on that later.

You should also consider what type of plants you’re growing. Different plants have different root structures and require different amounts of water and nutrients.

Make sure to choose a medium that will accommodate the roots of your particular plants. So, do some research – whether you’re going hydroponic spinach or hydroponic onions, or anything in between. You should also consider the climate you’re growing in. If you live in a hot, dry climate, you’ll need a medium that retains moisture well. Conversely, if you live in a cool, wet climate, you’ll need a medium that drains well to prevent your roots from rotting.

Finally, you should factor in the level of experience you have as a grower. If you’re just starting out, you might want to choose a simpler medium like coco coir or clay pebbles. As you gain more experience, you can experiment with more complex mediums like coco peat, rockwool, perlite, or vermiculite.

No matter what type of medium you choose, make sure to do your research and select the one that’s right for you and your plants.

So – Which Hydroponic Growing Media Should You Choose?

Now that we’ve covered all the different types of hydroponic media you can choose from – and just discussed the key factors to consider when choosing – which of these is right for you?

As we mentioned, it will come down to your unique grow and your preferences. However, there are two types in particular that we prefer: coco coir and clay pebbles.

These offer the simplest growing experience possible.

This is because they offer a great balance of aeration and water retention. Of course, clay pebbles offer more aeration – while coco coir offers better water retention. Ultimately, either one of these will present a great base to start your hydroponic crop around.

The one exception we want to make note of is if you’re looking to start your plants directly in their hydroponic system. If you do want to go this route, we encourage you to give rockwool a try. Why?

Rockwool starter blocks allow you to easily transplant your plant into a new growth module after it’s sprouted and grown a root mass. We love starting our seeds – or even clones – in rockwool for this exact reason.

Once the time comes, we’ll transplant the rockwool-grown plant directly into a growth module with coco or clay pebbles. You can learn more about how to start hydroponic seeds or hydroponic cloning in our blog.

Closing Thoughts on Our Guide to Hydroponic Media

We hope this guide to hydroponic media has provided you with clarity on the topic. Remember – hydroponic growing medium can be any inert material that holds your plant’s roots in place in your hydroponic system.

That means no nutritional content whatsoever. Besides anchoring your plant and providing structure, the hydroponic growing media is responsible for helping maintain a good balance of water retention and aeration.

And, now that we’ve broken down the various hydroponic growing media you can choose from – along with the pros and cons you gain from each type – there’s only one thing left to do.

Choose your own and get started growing! If you’re looking for recommendations, you can’t go wrong with brands like Mother Earth, Botanicare, or Fox Farm. Because grow media is so bulky, buying it online and getting it shipped is far too expensive – just head to your local hydroponics store or garden center.