Is Kanuma Soil Good for Succulents, Bonsai & Cactus?

Choosing the right soil mix for your succulents is important but it does not need to be a complicated process. There loads of options available in the market ranging from Akadama, Cactus soil mix to Kanuma soil. So let’s take a deep look if Kanuma soil is the right soil mix for your succulents or not…

Is kanuma soil good for succulents? Kanuma soil is highly lightweight and supports faster drainage. It is probably one of the most lightweight substrates out there. Hence it helps in keeping the soil mix less dense as a result of which the succulent roots can enjoy better aeration and drainage.

Table of Contents

What is Kanuma Soil in the first place?

Kanuma soil is the baked substrate obtained from the Kanuma region in Japan. They are volcanic rocks that are firstly mined from the soil and then carefully processed, sterilized, and baked. It acts as an excellent substrate for growing plants that love to thrive under slightly acidic conditions. Kanuma soil is one of the two most popular soils along with Akadama used in Japan for gardening and growing indoor plants.

This makes them perfect for being used for growing succulents, many bonsai plants, and other indoor plants that thrive best under slightly acidic pH. Kanuma soil is popularly used for growing bonsai plants like Azaleas, Camellias, Gardenias, etc.
These plants love growing in acidic medium and can even thrive fully under Kanuma soil substrate. It can also be used for growing succulents however you need to mix it with other soil components like coarse sand, gravels, and potting soil to give it a solid base.

Kanuma Soil Benefits

Kanuma soil is highly porous so it can retain a certain quantity of moisture while draining off the excess water. This limited moisture-holding capacity helps the roots to absorb the needed quantity of water without having to sit in a waterlogged condition for hours straight. As the Kanuma soil is porous it also helps in trapping better nutrients in the soil which further promotes better root development.
Facilitates better root development. Kanuma soil particles are smaller in size and promote the roots to develop freely. As a consequence of which the roots are being able to breathe much better and go much deeper and grow up to be much stronger.
Better root development means better supply and absorption of minerals and water for the rest of the plant. Succulents and bonsai with a stronger base foundation are likely to grow up to be stunningly beautiful and healthy as the root health is directly proportional to the overall succulent health.
Kanuma soil is so lightweight that it facilitates better aeration in the soil. This means the soil gets a better dosage of oxygen which further helps them to develop to be much healthier. Also, the chances of fungal or other microbial growth in the soil decrease a lot as the soil does not remain moist for long. So it indirectly contributes somewhat to preventing pest manifestation and root rot.
Like Akadama, Kanuma soil also helps in the development of fibrous root growth which is beneficial when repotting. You dont have to go through many hassles as the roots won’t be too hard and you can effective get rid of the excess soil.
Kanuma Soil looks stunning when used as an additional top layer around the stem base owing to its color.

Cons of using Kanuma as a Substrate

It is extremely lightweight in nature. As a result, when watered it can end up floating above the topsoil just around the stem base. This is something that won’t happen always but can occur sometimes. This is the same thing which you will face with Perlite as well. These components have got so many benefits because they are so lightweight however this is a downside for that.
Kanuma soil can be more acidic than Akadama hence it must not be used for growing succulents all alone. You need to mix sufficient amounts of other soil components to make sure the soil is not too acidic. Succulents best thrive under acidic conditions of 6 to 6.5. Whereas you could have used Akadama in the majority for growing succulents without any issue.
The availability of Kanuma soil is scarce depending upon where you live. As it is produced mainly in Japan, it is not found easily in other countries of the world especially in the western world. Most of the time it can remain out of stock and it can be really hard for you if you really become a fan of this soil.
As the availability is low and it is only produced from Japan hence it is not cheap. There are many cheaper alternatives that you can find in most cases which more or less does the exact same job as Kanuma soil. Kanuma soil is famous and popularly used in Japan along with Akadama as they are abundantly available there.

It is not mandatory that you need to use them to grow the best succulents or bonsai. You can try to avail them online or from your local nurseries but in case you, can’t find them you should opt for other alternatives as there are loads of them out there.

How to use Kanuma soil

You can mix Kanuma soil with Pumice, Sand, and Potting soil. The soil components you wanna use with Kanuma soil and their respective quantities totally depend on you as there is no one perfect recipe. Growing succulents entirely on Kanuma can be slightly risky owing to its acidic pH.

Also, it can break down within 1 to 1.5 years however that is not the case always. So mixing other soil amendments helps in keeping the soil structure intact, keeps the pH under control, and also is cost-effective as well.

So using Akadama or Pumice or perlite along with Coarse sand and potting soil is a great option.

Kanuma Soil Substitute

In case you cant find Kanuma soil in your place you dont need to get worried as there are many substitutes available. The most popular substitute for Kanuma in the west is the volcanic rocks.

Kanuma Soil vs Pumice

Pumice is extremely lightweight and porous in nature. It holds almost no water and can trap minerals as well. Hence it also supports vigorous root growth. But unlike Perlite and kanuma it does not float up when watered.

Also, Pumice is internationally available everywhere. So it can be the perfect alternative for growing succulents.
It does not contribute anything to the soil pH. So you can grow succulents purely based on Pumice.

Kanuma soil vs Akadama

Akadama is more readily available than Kanuma however it may vary based upon where you live. Kanuma is quite acidic in nature which is not the case with akadama.

You can even use Akadama and grow succulents wholly on them and they will turn out to be great! But you should mix other soil components with Kanuma soil. Akadama has got stunning drainage properties and comprises all the benefits of Kanuma soil. Along with this, Akadama can let you know when is the right time to water your plants.

Both Akadama and Kanuma soil changes color when wet and it comes back to its lighter shade when it dries up again. This cue can be highly beneficial for preparing your watering schedule accordingly and to make sure you dont overwater your plants.
Akadama is also less light than Kanuma soil so it will never float up when watered. Kanuma soil is also much softer in texture.

You can read more on Akadama here: Is Akadama Good for Succulents & Cactus? (Pros & Cons)

Other notable substitutes include Perlite and Diatomite.

You can read more about Perlite here: Is Perlite good for Succulents? (Substitutes included)

Things to remember while using Kanuma soil

Kanuma soil is acidic in nature and has a pH of around 4.5 to 5 (source). This is one of the reasons it is primarily used for plants known to survive in acidic conditions only. Hence you should not use it all alone for growing succulents as for most succulents the comfort zone is 6 to 6.5.
In case you feel your soil has become alkaline in nature with time, you can buy your own pH kit online or from your nearest store and go through your own soil pH test which is super easy. After that, you can add Kanuma soil accordingly.
You should always use Kanuma soil along with other soil components and not all alone. You can use succulents to grow totally alone on akadama medium or pumice medium but you should try balancing out the pH when using Kanuma soil.

Conclusion

Kanuma soil is a suitable medium on which you can consider growing your succulents especially if you live in a very humid place. It will help in faster drainage and support suitable aeration that will lead to better root development. However its availability can be a factor but in that case, you will have a lot of alternatives to play with.

You can experiment with various soil components and in the end, the soil should be sufficiently drainage friendly and support aeration. That is all. Succulents are adaptive plants they will take care of the rest from here.