Using Molar Clay As Bonsai Soil (Using Cat Litter)

Molar clay is a commonly used, but controversial component used for bonsai soil.

A lot of the controversy is around the fact that it is sold as cat litter, however, it can actually be a pretty good material to use as soil …so long as you buy the right stuff and actually buy molar clay.

I will go through how we can use it and more importantly what you should actually be buying as it can be very easy to buy the wrong stuff and this will not work properly and cause your tree a lot of problems.  

What Is Molar Clay?

Molar clay is basically a natural occurring rock that is made up of diatomaceous earth (which means the skeletons of sea creatures) and it is then treated with very hot temperatures which makes it “calcinated” which is why will hear it also being called a “baked clay”.

The final result is a very hard, light weight, absorbent and heat resistant.

It is found in large quantities in Denmark and is used in a various number of ways across many industries especially as an absorbent for industrial chemical spill clean ups. It is also used as cat litter and is even used in steelmaking and construction among many other things.

When you look at it, it is just a bunch of pink little stones. It can sometimes be a little dusty and it does have a unique smell, but this all very natural. 

How Can We Use Molar Clay In Bonsai?

Molar clay can be used in any realm of horticulture, including bonsai, as a soil conditioner.

We can add it to a soil mix, or use it totally on its own. Its light weight and ability to hold water makes it an excellent addition to the soil. It will help with drainage, increase aeration, but it will also hold moisture and nutrients that the tree can use.

Molar clay is often compared to akadama and for good reason, they do have a lot of similarities (although some differences) and they can both be used in bonsai soil.

(You can read more about – What Is The Difference Between Akadama And Molar Clay?)

How Is Molar Clay Sold?

Molar clay is sold as …well, molar clay. You can literally find people selling it as this.

However, it is not always branded like this and you are much more likely to find it as either cat litter, or absorbent granules. 

It gets bagged up and branded as these and when you inspect the “ingredients” you will see that it is actually just a bag of 100% molar clay.

I will go through some actual products you can buy a bit further down as there can be a bit of confusion about what to buy, especially when it comes to cat litter.

Are All Cat Litters Suitable As Bonsai Soil?

When you hear people talk about bonsai soil, you will hear “molar clay” and “cat litter” being used interchangeably and this has lead to some confusion and misinformation.

You cannot use all cat litter as bonsai soil. The cat litter has to be 100% molar clay.

So long whatever you are using is molar clay, then it is fine. The statement should really be “all cat litter made from molar clay can be used as bonsai soil” which should hopefully lower the confusion levels.

If your cat litter is made out of anything else, which it often is …then it will not be suitable. I do believe there is some that is made from turface, which my understanding is that it should be fine to use …but I have no had my hands on this to test …so for now my official message is “if it is not molar clay, it is bad”.

This message seems to have been lost and people just hear cat litter and do not realise there are different types. 

If you use any other type of cat litter it can just basically dissolve and turn into a sort of sludge, which is the complete opposite of what bonsai soil should be. 

Why Are People Against Using Cat Litter?

You will encounter a lot of negativity around cat litter and some people are very against it and really think this comes down the misinformation I spoke about before.

You will usually hear something along the lines of “you wouldn’t plant your best trees in something that a cat poos in”

Which is fair enough, but at the same time, what if it was never used for cat litter. What if it was only ever sold in bags that says “natural fired clay” …would that be fine?

What would they say if it suddenly became very popular in Japan to use akadama for cat litter… would that then make it a bad soil component? What if they sold it in pet stores for half the price… would they go there and buy it?

Some of the hate is justified, since most cat litters are not appropriate material anyway, but to hate on molar clay is not really justified.

You will also notice I only ever call it “molar clay” to not activate the anti-cat litter people and if we are being honest, I think my soil is more absorbent granules than cat litter …but either way, it’s all molar clay.  

What Cat Litters Are Actually Molar Clay?

So the real question I get asked a lot is around what or where to buy cat litter. What ones are right and what ones are not. I will go through what I know you can get in the UK, and then some other places.

The availability or ingredients changes from time to time, so this is always something you should check before buying.

Cat Litter In The UK

The main cat litter you can use is Sanicat Pink, although this seems to have been rebranded as Kitty Friend Pink. This was on Amazon and pet stores, but it seems to be harder to find these days. This company offers other types of cat litter… these are no good. It has to be the pink one.

Tescos own brand cat litter was a very good option. Although they no longer make this …if you go to tescos now, they do not seem to stock any molar clay cat litter. So sorry, Tesco’s is out.

For those of you in England, Wilkos used to sell a molar clay cat litter …but this appears to be gone now too and replaced with other alternatives that are no good for bonsai soil.(and Wilko has shut down, so its very much out too)

So really it looks like a lot of cat litter brands are no longer using molar clay. I am not sure why, but this is extremely annoying as it makes sourcing the molar clay a lot harder.

Cat Litter in Europe

Sorry Europe, you seem to be lacking in the cat litter department. All you seem to sell is some vegetable based biodegradable stuff which is really not what we want for our bonsai soil.

I of course haven’t checked everywhere, I am sure one country will have molar clay cat litter since a lot of it does come from Denmark, but I can’t find it. If you know of any brands, let me know!  

I do have a feeling that some countries will sell the Kitty Friends Pink that we have here in the UK, if so, get that!

Cat Litter In The USA

When it comes to the USA… well, I don’t live there which makes it very hard for me to check.

However, from what searching I did I don’t seem to be able to find any molar clay cat litter.

Walmark came close, but the colour is off, it’s grey. I think this may actually be some sort of turface …so potentially it is okay, but as I said I don’t live there so I can’t check. I cannot promise you this will work, but it may be worth buying and testing (and then telling me the results)

What ‘Absorbents Granules’ Are Molar Clay?

If you are struggling to find cat litter, then you should look at the absorbent granules section of the shop. This is the stuff that you throw on the ground to deal with oil spills and stuff like that …but of course it is actually good old molar clay. It’s the exact same as the cat litter, just in a different bag.

The one I have bought in the past is called “New Safety Tread Absorbent Granules” It’s a huge 30 litre bag and is available on Amazon and Screwfix. I think it even says “Danish molar” or “Pink Danish” on the bag, so you know its good the good stuff that we need.

Just like the cat litter, there are plenty of absorbent granules that are available, but they are made from some other substance that is not ideal for bonsai, so always make sure it is molar clay you are buying.

When we look at molar clays uses, one of the biggest is chemical spill cleanup, so I am fairly certain you are more likely to find it across Europe and America sold as some sort of absorbent, rather than cat litter.  

Americans, I also am not sure, but I have a strong belief that the red stones you use on your baseball fields is molar clay. It could be turface, but either way this is an area you need to investigate. Whatever that stuff is, it is used as an absorbent and I have a very strong suspicion is can be useful to us (but I cannot confirm this! so don’t take this as gospel!)

Should You Buy Cat Litter If You Are Not Sure What It Is Made Of?

If you can find the cat litter or absorbent granules I have mentioned above and you are satisfied they are molar clay …then buy them

However, you can see I was a little vague for the rest of Europe and America, so should you just buy cat litter if you are not quite sure what it is made of?

My answer is yes, but this comes with a huge caveat. You need to test the soil before you use it with your trees.

I would first start of by trying to buy something that is most likely molar clay … is it pink? Is it described as perfume-free, non-clumping and dust-free? (It will be dusty, but this washes away when you water it).

If you are seeing anything like this you may be looking at molar clay. I would buy it …then test it to be sure.

If you want to be extremely sure you could even email the company and ask them.    

Use The Water Test

The first test I would do on any cat litter is simply pour water on it. Put some in a glass and fill it with water and leave it there.

If its molar clay, nothing will happen. If it’s basically dissolves or turns to mush… you can’t use it as soil.

This can give you a quick idea if what you have bought is usable, but it doesn’t show you if it can last long term, to do this, you need to do the freeze test.

Do The Freezer Test

All you need to do is wet your cat litter and then put it in a bag and freeze it.

Take it out after a day and defrost it. Hopefully it is still solid after it thaws. If it turns to mush …you don’t want to use that on your trees.

You could repeat this a few times over a week and see how the soil holds up. This is going to give you a real idea if it can handle the freeze-thaw cycle a number of times or not.

Use It On One Tree For A While

If you have tested everything and you are still a little unsure then just test it with one tree you are not really worried about, maybe one that has popped up in your garden, or a seedling you are growing… basically something you don’t care if it dies or not …so don’t use any of your fancy trees.

Mix up some cat litter into a soil mix and use it with this tree. I usually start with equal parts molar clay, compost and perlite.

Just grow this for a season and see how things go. It is a long time to wait, but at least you will know the longevity of the cat litter you bought. If it seems legit and you are now certain it is molar clay …roll it out to the rest of your trees and use it in whatever way you want to.

Conclusion

Hopefully this clears up some of the confusion around cat litter and bonsai soil …so long as its molar clay, it is a viable option for your soil. If it is anything else it will probably turn to mush and it will not end well.

If you are not sure, use the tests I suggest and you should be pretty safe. Molar clay can really be a great soil component and I have had a lot of success with it and there is no reason why you cannot too.

(You can read more about – A General Guide To Bonsai Soil)