Building Healthy Trees from the Roots Up
If you are new to bonsai, choosing the right soil or substrate can be a little confusing. Akadama, pumice, scoria, different mixes and different ratios — there is a lot of information out there and plenty of different opinions on what works best.
One thing we have learnt at Embark-en is that there isn't necessarily one perfect mix for every tree or every grower.
What is important is understanding what each substrate does and why we use it.
After all, we spend a lot of time looking at the parts of our bonsai we can see — the trunk, branches, foliage and overall design — but ultimately, a healthy bonsai starts with a healthy root system.
What Are We Looking for in a Bonsai Substrate?
Unlike normal garden soil or potting mix, bonsai substrates generally consist of larger, more consistent particles.
This helps water move freely through the pot while still allowing the substrate to hold enough moisture for the tree. Just as importantly, the spaces between the particles allow oxygen to reach the roots.
In simple terms, we are looking for a good balance between:
- Drainage
- Water retention
- Aeration
- Good structure
The right balance will depend on the tree, your climate, the pot and even how often you are able to water.
This is where different substrates come into play.
Akadama
Akadama is probably one of the best-known substrates used in bonsai.
It is a naturally occurring granular clay from Japan that has been used by bonsai growers for many years.
Akadama is popular because it holds moisture while still allowing good drainage and airflow around the roots. It can be used by itself for certain applications or mixed with other substrates such as pumice and scoria.
For us, Akadama is a great base when building a bonsai mix because it gives you that balance between holding moisture and allowing the roots to breathe.
Pumice
Pumice is a lightweight volcanic material with lots of small pores throughout each particle.
These pores allow pumice to hold some moisture while still providing very good drainage and aeration.
It is also quite stable, so it helps maintain structure within the pot rather than quickly breaking down and compacting.
Pumice is particularly useful when mixed with Akadama and scoria and is something you'll find in many bonsai substrate recipes.
Scoria
Scoria is another volcanic material and is something we really like using in our mixes.
It is hard, porous and free draining, helping keep plenty of air movement around the root system.
Because it doesn't easily break down, it also helps maintain the structure of the substrate over time.
At Embark-en we use black scoria, which can be used on its own or mixed with Akadama and pumice depending on what you are trying to achieve.
Why Do We Pre-Screen Our Substrates?
This is something that was important to us when we put together the Embark-en substrate range.
When you buy substrate in bulk, there can often be quite a lot of dust and very fine material mixed through the bag.
The problem with these fines is that they can work their way down between the larger particles and reduce some of the air spaces we are trying to create.
So we screen our packaged substrates to remove much of this unwanted material.
Our pre-screened substrates are screened and packaged by hand, meaning you can open the bag and get straight into repotting without having to spend time screening small quantities yourself.
It takes us a little more time to prepare them, but we think the consistency and convenience are worth it.
Our Premium Bonsai Soil Mix
We also wanted to offer something for people who don't necessarily want to buy several different substrates and mix everything themselves.
Our Premium Bonsai Soil Mix combines:
Akadama + Pumice + Black Scoria
Each material brings something different to the mix.
The Akadama helps with moisture retention, while the pumice and scoria provide drainage, aeration and structure.
It's also pre-screened and ready to use straight from the bag, making it a simple option for beginners or anyone who just wants a good general-purpose bonsai substrate without having to mix their own.
What Mix Should I Use?
This is probably one of the most common questions when it comes to bonsai soil — and unfortunately there isn't one answer.
Different species have different requirements.
Your local climate makes a difference too. Someone growing bonsai in a hot, dry part of Australia may want their substrate to retain more moisture than someone living somewhere cooler and wetter.
How often you water, the size of the pot and whether the tree is in development or refinement can all make a difference as well.
That's why we think it's more useful to understand what each substrate actually does rather than simply following one recipe.
Once you understand the different components, you can start adjusting your mix to suit your trees and the way you grow them.
And like most things in bonsai, you'll learn a lot from simply trying different combinations and seeing what works for you.
It All Starts Below the Surface
We spend years developing trunks, branches and foliage, but none of that happens without a healthy root system underneath.
Choosing the right substrate gives those roots the environment they need to grow and develop.
Whether you prefer to create your own mixes or use something already prepared, understanding what's actually in your bonsai pot will help you make better decisions for your trees.
At Embark-en, we've put together our substrate range to make quality bonsai materials more accessible, whether you need individual components to create your own mix or a pre-screened blend that's ready to use.
We're bonsai enthusiasts too, and we're always learning, experimenting and refining what we do.
Because that's part of bonsai.
We hope this clears up some of the confusion around bonsai substrates and helps you better understand what might work for you and your trees.
- Embark-en Team.
Design. Create. Cultivate.
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