Having the correct bonsai soil mixture is without a doubt one of the most important parts of keeping a bonsai healthy. Buying bonsai soil mix can be an easy solution but learning how to mix your own soil is going to allow you to tailor the soil to the bonsai tree species and save you a bit of money!
Bonsai trees require a perfect soil mixture to stay healthy, usually comprised of Lava Rock, Pumice and Akadama. The ratios differ per species but for the deciduous trees 25% Pumice, 25% Lava Rock and 50% Akadama is a great mix.
Qualities Needed In A Bonsai Soil Mix
Although there are a lot of qualities that you may be looking for depending on your trees species and growing conditions, the universal qualities are…
Aeration – The soil mix will allow tiny pockets of air in the soil, allowing oxygen to reach to roots easily.
Drainage – When watering a bonsai, the water needs to be leaving via the drainage holes straight away, not sitting in the soil. The perfect soil mix will allow for quick drainage, to avoid the tree getting root rot or other diseases.
Water Retention – Although drainage needs to be good, the soil also has to retain some water in order to keep the tree thriving until its next water.
Mix Your Own Bonsai Soil (Step By Step)
Mixing bonsai soil has a knack to it in order to achieve the perfect balance of components but the actual process is very simple, it really can’t go wrong!
Step 1 – Take your Akadama and sift it through one or two screens to remove all of the dust, which can stop the soil draining properly.
Step 2 – Repeat the process with the Lava Rock, sifting the dust. Don’t bother doing this process with the Pumice.
Step 3 – Get stuck in and stir up the ingredients until you have achieved a finely mixed soil!
Can Bonsai Trees Grow In Normal Soil?
A common misconception is that bonsai trees will grow fine in normal soil – typically they won’t. Bonsai trees need a lot of drainage or the roots are going to start rotting away. It’s for this very reason that in a bonsai soil mix different components are used to achieve the perfect level of water retention for vigor. A standard soil will usually not contain the high levels of nutrients that bonsai typically need during growing season to stay healthy. The low quality of soil that is found in most garden does have a few uses, such as burying your bonsai pot in it when you go on holiday but beyond that it’s not too useful for this art. For more information on keeping your tree alive when you’re on holiday
, check this article I just published!
Bonsai Soil Breakdown
Whether you typically buy a standard bonsai mix soil on Amazon
or you always create your own, it’s worth learning about the different components so you can tailor your soils to your trees. It’s not too complicated once you get the hang of it!
Firstly, there are two different classifications of soil, either Organic or Inorganic. The organic soils will contain parts of plant in them, bark and peat being the most commonly found. The inorganic soils don’t contain any plant matter, meaning that they cannot absorb as much water, however in terms of drainage they are phenomenal. Soils containing organic materials can absorb a lot more water and nutrients, however over time the material will start breaking down and causing you a few problems.
Secondly, let’s look at the main/most commonly used components of a soil mix.
Lava Rock – Roots don’t grow in lava rock, however, it is great for water retention and stability so it’s commonly used in high quality soil mix.
You’ve probably heard of this in terms of volcanoes! This absorbs nutrients and some water, meaning it’s perfect to use for water retention in the mix. If you’re struggling to find this at nurseries near you, like I was, check out the option of buying your Pumice from Amazon.
This is a special clay originating from Japan, specifically created for Bonsai use. It’s reality expensive so people tend to look for alternatives such as other baked clay, however if you’re looking for a high quality mix, you need to use this! The downside of Akadama would be that it does breakdown after 2-3 years but most people repot every few years anyway so this isn’t so much of an issue. You can pick up some high quality Japanese Akadama on Amazon.
Recommended Soil Mix For Your Bonsai
For the best results when growing bonsai, you want to research the needs of your specific tree species when it comes to the soil mixtures needed for optimum growth. However for the majority of bonsai hobbyists, just two different soil mixtures will typically be fine.
The two different soils are broken down into either deciduous or coniferous, depending on the species of your bonsai. It’s also important to note that the mix can be slightly altered depending on what sort of conditions your tree is growing in. For instance if you work long days and have a lot of commitments, it’s unlikely that you’ll be able to check on your tree twice per day. The ideal solution for this would be to add a slightly higher amount of Akadama, which will increase the soils water retention levels so it’s less likely to dry out fast.
If you have less time to dedicate to the maintenance of your bonsai trees, water retention in the soil mixture is going to be key. Providing you have increased the amount of Akadama, another viable option would be to start growing bonsai moss on the top soil. Beyond the benefits of water retention, this can provide an amazing aesthetic for your tree, creating a more realistic feel for the bonsai. I have recently put together a guide about growing bonsai moss and the benefits of it
, so give it a read if you are interested!
For a coniferous soil mix – 1/3 Pumice, 1/3 Akadama, 1/3 Lava Rock.
For a deciduous soil mix –
1/4 Pumice, 1/4 Lava Rock, 2/4 Akadama. For more information about deciduous trees, checkout this guide I put together!
It’s worth noting that through my research, it really does seem that most long time bonsai enthusiasts tend to have their own system when it comes to the perfect ratios in bonsai soil.
Bonsai Soil Mix Video