Whether you are newbie or advanced succulent grower, I am sure that you know the succulents are desert plants which mean they strive for soilless mix. Actually I don't think we should even call 'soil', so let's change to it to 'potting mix' or 'substrates'.
The key of potting mix for succulents is to promote porosity while retain the moisture.
We should know by now that peat or general compost mix are not quite suitable for succulent. In case you are wondering, yes, not even 'Westland Succulent Potting Mix' I used them years ago and they retained too much of moisture. Another one is 'Cactus Refocus Potting Mix' which contains peats, sand, grit and loam; this potting mix is slightly better. It's totally fine to still use them but I would recommend adding other growing media (see below) into your store-bought potting mix to promote better air circulation and water drainage.
Well I know from my beginner guide that I recommend standard compost + perlite and vermiculite + clay pebbles. Don't get me wrong that this is still one of my go-to potting mix. I find this is perfect for young succulents or new plants that require rooting.
Anyway based on my answers from my questionnaire, it seems many people have issue with perlite 'floating' on top of soil after watering. Simple solution: add a layer of decorative grit or stones.
Since I have more matured plants (FYI majority of my plants I'm selling are matured) which mean they need different types of potting mix. Matured succulents have less demand for water and in fact they require high porosity. Matured succulents are almost like Bonsai (don't you agree?) and my Korean suppliers grow them with bonsai potting mix. FYI bonsai potting mix tends to be soil-less.
Before we get started, I would like note that these are not affiliated products eventhough I wish they would sponsor me. These are based on my experience and hours of research. Again I'm no expert and still learning every day to discover alternative potting mix.
Volcanic Rock aka Lava Rocks aka Lava Cinders (Highly Recommended!)
There are two types of horticultural lava rock; black or red (lapilli or lapillo). Lava rocks have high levels of iron, magnesium, nitrogen and other minerals which are excellent for healthy succulent.
The one I bought from Amazon Prime is lapillo from Italy (I think) which is around £18.30 for 20l and comes in various sizes (upto 25mm). These chunky lapillos are very versatile; not only they look pretty as decorative top they have good moisture retention whilst providing nutrients to my succies. Lapillos tend to be little heavier than the rest. If I crush the chunky lapillo I do get some grits and use as grit sand too. Also do you know their red earthly tone would get darker when moisten too?
I have also bought the black lava rock (they are not entirely black) from Amazon Prime (£25 for 25kg) and I absolutely love their texture as they come in smaller sizes between 1-5mm. Most importantly they have been washed hence the dirt is very minimal. Do you have any idea how much time I could save from crushing the rocks? The answer is alot.
Crushed Lava Rocks (my favourite so far)
I also recommend Kaizen Bonsai as they do provide finer lapillos at very reasonable rate. You could skip using the plant food (for succulent) if you manage to get volcanic rocks as part of your potting mix.
My verdict: GET THEM whether it's black or red!
Akadama - Volcanic Clay
Akadama has been priced by many bonsai and succies lovers. Japanese and Korean grow their succulents in pure Akadama soil. Akadama is Japanese volcanic clays which retain moisture whilst providing good air circulation. The reason they are popular as these are one of cheapest growing media available in Japan however a bag of imported Akadama probably costs around £20-28 for 14 litre. I only have the smaller bag of 7l and mix some with others. I can see why these are popular as they are quite lightweight but heavy enough not to be blown away by strong wind.
My verdict: honestly I am not sure, I keep going back to buy more as they look great when mixing together, but I guess the main reason is because Akadama is part of volcanic particles which provide natural nutrients to succulents?
Seramis- Clay granules
Seramis is clay granules from Germany. The clay undergoes a special porisation process to achieve a incredible pore volume of over 80%. The clay is then fired at a particularly low temperature which helps to even further increase it’s water-holding properties. So in a way Seramis is calcined clay not really baked clay but they retain moisture and provide good air circulation. I also would like to note that they are little pricey approx £10.95 for 7 litre from here so it's moot point here.
Horticultural Moler Clay
aka Danish Pink or Biosorb. You probably wonder why I am talking about cat litter. The Horticultural Moler (which sells £9.75 for 14l by Kaizen Bonsai) are suitable for horticultural as these have been pre-washed. This super tiny calcined hard clay holds a staggering amount of moisture whilst still allowing good air circulation.
These are probably smallest growing media which I actually love to use them. Due to its properties, many manufacturer have repackaged them as cat litter. But apparently store bought car litter tends to be quite dusty and requires rinsing and drying before using. I actually use two sizes of Moler in my mix as molers tend to dry up faster compared to others therefore it's very useful especially during warm humid summer.
Turfaces is another calcined clay which has similar purposes but they are mainly available in America.
My verdict: any of horticultural moler, seramis or turfaces will do. I don't really have access to other two but I love the horticultural moler as the size is quite small and I feel that they give the roots to hold onto.
Kyodama- fired clay granules
Kyodama is the fired clay granules. Kyodoma doesn't break down and maintain a very high AFP (air filled porosity) which is important to prevent root rot! So of course I have recently joined the hype and bought one bag for myself. Oh yes, little pricey but they are quite light. Did I mention that they have good nutrient hold capacity?
My verdict: I love using them, I have managed to source the same version from Kaizen Bonsai (trade under different name due to Kyodama trademark). And I honestly love the texture.
Clay Pebbles- baked clay
In general clay pebbles are made by heating clay in a rotating kiln to 1100 – 1200 degrees Celsius. This heating process causes the clay to expand. The end result is a rough finished, highly porous medium that is excellent at retaining moisture, trapping air, and oxygenating any nutrient solution that flows over it. FYI clay pebbles are lighter than Seramis and Moler.
My verdict: It's no brainer, just get the clay pebbles for under the pot as these are super lightweight especially you have tall pot, and you can crush it to mix.
Pumice is basically volcanic glass and it's light weight. Pumice is able to absorb moisture and allow the moisture to be released when dry. The free draining open structure of this pumice also prevents water-logging and allows aeration and effective plant root development.
Unfortunately there isn't many option available for horticulture grade. The cheapest I could find is from Kaizen which starts from £8 for 7 litre. I have to mention that their Horticulrtural Pumice contains quite lotsa dust and the sizes are quite irregular so if you are the picky one, go for Ikea version which has been washed; £3 for 3l.
I have recently found the same supplier whom I got the lava rocks does have horticultural pumice and guess what they have been washed and quite small (between 1-4mm) which is extremely ideal. Little pricey £32.95 for 32 litre but I say worth it?
My verdict: probably one of most important substrates for me so GET them.
Kanuma- Japanese version of Pumice
Kanuma is basically Japanese version of pumice. Obviously these have been washed and the sizes are perfect. I was initially quite reluctant to buy as these are quite expensive too but the moment I've read that they are slightly acidic (ph 5.5) I was like 'just take my money'... Yes if I could save some time by collecting rainwater and substitute with slightly acidic substrates that would be great! I'm convincing myself it's going to be good investment.
My verdict: Kanuma is actually much lighter than pumice. I've read somewhere that Kanuma has better moisture absorption compare to pumice and I definitely agree with that as Kanuma gets quite gold when wet and it retains the moisture longer than pumice. The one I got is around 3-5mm therefore it does give good volume to the mix. I'm completely sold but Kanuma is definitely the most expensive substrates compared to others.
This is actually not growing media but Rootgrow contains organic Mycorrhizal fungi which provides good boost to succulents. Rootgrow has many benefits including encourage good root system. You can get it pretty much from every garden centre but again for someone (like me) whom works 5 days a week, Amazon Prime would be most ideal way as I want all orders arrive before Saturday so that I could spend the whole weekend in my garden.
My verdict: Get them, I find my succulents root better.
Potting Grit and Grit Sand
Majority of the potting grit (£5 for 5kg) is made of crushed limestone and granite.They do also provide good drainage whilst retaining moisture too. These are cheaper and good option too.
My verdict: If you are planning to buy the growing medias above, skip these. Potting grits and sand tend to be little heavier hence you if you are getting these, make sure you do mix with other lightweight growing media. Potting grit does look great as topping too.
Potting Mix Ratio
So let's talk about the ratio. Seriously there are so many different ratio out there but the golden ratio is always 1 part of everything.
The easiest way is 1 part of everything:
- 1 part of Moler/ Akadama/ Seramis/ Potting Grit
- 1 part of Pumice/ Kanuma
- 1 part of Lava Rock
- 1 part of Sand / Potting Grit (optional)
- Optional: handful of normal peat soil (if you are little freaked out about my crazy soilless potting mix)
Budget friendly way:
- 1 part of Lava Rock
- 1 part of Sand/ Potting Grit
- 1 part of Perlite or Pumice
- 1/2 part of Clay Pebbles
- handful of Vermiculite
- handful of peat soil
The one I'm currently using:
- 2 parts of medium Lava Rocks
- 1 or 2 parts of Horticultural Pumice ( I have 2 versions now)
- 1 part of Horticultural Moler (as they are very tiny)
- 1 part of Kyodama
- 1/2 part of Akadama
- 1/2 part of Kanuma
- 1 spoonful of Rootgrow (it comes with a scoop)
- And I use clay pebbles/ lapillo for pot bottom.
Substrates version 2.1 with new introduction of Kyodama (similar version) and Kanuma into the mix.
You can use the potting mix above for your young succulents but I have let you in advance that your succulents will take longer time to adapt due to soilless potting mix but they will grow stronger and form 'woody' stem once they have adapted.
And always remember to root them first before repotting.
And no water for at least 1 week.
Succulent is an expensive hobby and requires lots of effort and time. To be honest, there is no fixed ratio and really depends on your own preference, the most importantly your budget too. As these growing medias are pretty much retain good moisture whilst providing porosity, you can really play around with the ratio. Sometimes I just mix whatever that's available.
Before & After
As you can see the left was grown since April 19 in substrates mix + rootgrow vs the right grown in normal soil + perlite since Nov 18. You can see the huge comparisons between these two. FYI the picture was taken in Nov 19. ps: it's good sign if your succulents are root bound that means you have healthy succulents and ready to be stressed.
I understand that if you are a newbie simply do not have the space to store so many different types of mixes, I have now starting to sell hand mixed potting soil. You can now buy from here:
If you are unable to get any of these substrates, it's totally fine. Normal compost + vermiculite/ perlite will do the job or if you are having second thought about normal compost after reading this yet still can't get the substrates, just walk into any building supplies and ask for really gritty sharp sand. They work!