First of all I would like to start by saying that there is not one perfect mix for everyone which, as a succulent grower, I completely understand. Also different people may have different experience with the same product and so sometimes a bit of trial and error is needed to find the best potting mix for your plants needs.
Factors such as climate, where your succulents are kept and the type of succulent should also be taken into consideration when choosing succulent potting mix. To read more about how climate or the plants position could affect the choice of potting mix, read this article to the end.
Succulents and cacti are hardy plants that require little care. Planted in the ground, they will survive in poor soil, but they will probably not grow to their full size and the growth can be a lot slower than if they were in planted in good quality soil/potting mix.
To help garden succulent along, succulent potting mix (or other premium potting mix) can be added to the soil to create a breathable and well draining growing medium. In our opinion, succulents in the ground do not need extra special potting mix and will grow happily as long as they are not in flood areas or too much shade (unless you’re growing shade tolerant succulents such as Haworthia, Gasteria etc.)
Succulents in pots, however, should only be planted in the best potting mix you can find as the roots are limited to the pot and have to be able to get all they need from the potting mix. I have seen people planting succulents in just rocks and pebbles, but this will never sustain succulents long-term. The nutrients in the potting mix are needed for healthy growth.
Good potting mix for succulents should be light, free draining and not too sandy. When watering, water should soak straight in and go out the drainage hole retaining just enough to satisfy the plants thirst.
In our opinion, succulent mix should be able to hold some water back (but not be too soggy) so the plants don’t have to be watered all the time. It is hard to find the right potting mix and many people will prefer different brands. Judging by online reviews there is no popular Succulent and Cacti Potting Mix that 100% of customers approve of. It is often trial and error before the ideal potting mix is found. Having had a look at the options there are great and not so great mixes on offer.
Our Ideal Succulent Potting Mix
Good potting mix is very important to our small business and it really does make a difference to what the plants look like and how healthy they are. The potting mix for our nursery is specially made for succulents and cacti and is not sold at any store, but we have found a few succulent potting mixes online that look quite similar to what we get.
While searching online i have also seen many a succulent potting mix just made of peat moss and perlite. While this may be ok if you have a climate controlled greenhouse, it may not work great for succulents exposed to rain as peat moss can stay soggy for quite some time.
Extra Free-Draining Succulent Potting Mix
An extra free draining potting mix can be used if you live in a climate where it rains frequently and your succulents are outdoors, exposed to the elements.
To make one is very easy- simply add perlite, pumice or lava rock to your potting mix of choice. When we're expecting a particularly rainy season i'd usually add a fifth of pumice and perlite mix to a pot. Roughly divide a pot into 5 parts (you can use a pencil or marker) and fill with potting mix up to the fourth mark. Fill the rest with perlite/pumice/lava rock. Tip it all out into a bowl and mix thoroughly.
What is succulent potting mix made of and how to make your own?
A variety of ingredients can be used to make a succulent potting mix and depending on what you think is best for your plants the ratios can be adjusted to make the mix super free draining, slightly water retaining or a bit more soggy. The climate and where you keep your succulents should also play part in deciding how free-draining the mix will be.
So, for instance, if you live in a dry climate with infrequent rain, the potting mix can have more coir or peat moss to retain water so your succulents do not need to be watered every other day and also, so the potting mix does not become hydrophobic (so dry, that it will repel water).
If you, however, live in tropical/subtropical climate with frequent rains and high humidity, you might need to limit the use of coir/peat moss and up the pine bark fines/perlite/pumice to allow the water to drain freely and not choke your succulent. In our experience, succulents will survive rain (read more about rain and succulents here) as long as the potting mix allows the water to drain away, leaving enough air in the pot so the roots can breathe.
To make your own potting mix a variety of ingredients can be used. To keep the mix light, airy and free draining there is a choice of the following.
Composted Pine bark fines (not mulch)
These are a great soil conditioner and add extra nutrient as they break down. It is important to buy composted pine bark fines and not mulch. If not composted, they can harbour fungus.
Unfortunately, fungus may appear even in composted pine bark as spores travel in the air but the chances are lower. To be honest, fungus in the potting mix is pretty common, especially when rainy weather comes along.
We have only used lava rock briefly in a new potting mix we trialled a couple of years ago, but found the rocks to be a bit too big for our needs, especially for our smaller succulents. That, however, does not mean it is a bad product.
Pumice is also a type of lava, but very light and porous. It forms when the gas rich lava with high water content froths and solidifies at rapid rates. In our opinion, pumice is one of the best ingredients for a homemade succulent & cacti potting mix.
Pumice sucks up excess water but then releases it at a steady rate, which keep the roots from being over-saturated, but still nourished with water. It is also very high in minerals that your succulents will love. Pumice comes from mines and is completely natural and organic. It does not decompose or rot and so will not attract fungus unlike pine bark fines can.
Perlite is another type of lava glass, but it is even lighter than pumice. The two are quite similar and are both a great choice for diy succulent potting mix. Perlite tends to be a little too light and blow away in the wind or wash out from the top of the pot in the rain.
Both Perlite and Pumice will hold what you water with which is great as they can become a bit of a slow release fertilizer if you water your plants with liquid succulent fertilizer. It is hard to choose between the two- some people swear by pumice and some by perlite. Again, it comes down to personal preference. We use both, mixed together.
People often confuse perlite and vermiculite, though they are quite different. Vermiculite is made from compressed silica materials and although it helps add drainage and aerates potting mix, it can also make the mix a little damp.
This would be a good option for dry climates. There is one more thing to consider- vermiculite has long been associated with asbestos though it is said today's gardening products should be safe to use.
The scare started when Vermiculite was mined in a North American Libby mine where asbestos was also present in the same rock formation (Vermiculite and Asbestos sometimes naturally occur in the same rock formations) and so Vermiculite from this particular mine was contaminated with asbestos. The Libby mine closed down after the discovery of asbestos. Tests are carried out at other mine sites to make sure that the Vermiculite sold to the public is safe. However we found this extract in the ATSDR (Agency For Toxic Substances & Disease Registry) https://www.atsdr.cdc.gov/NEWS/vermiculite051603.pdf
Is there asbestos in the vermiculite sold for gardening uses? Not all vermiculite garden products contain asbestos, but an EPA study showed that some contain low levels of asbestos.
Asbestos was found primarily in the unmixed vermiculite product sold separately as a soil amendment. However, some was found in premixed potting soils. Because the Libby mine closed in 1990, newer products are not expected to contain significant amounts of asbestos. It is possible, however, that some older products could still be on store shelves “
I'd also like to add that when working with any kind of potting mix or using gardening products, a dust mask should be worn so you will not breathe small particles in. Even with asbestos not taken into account, breathing in tiny particles and dust that are part of potting mix or other media used making potting mix is not good for your health and can aid in respiratory diseases.
Just to be absolutely clear, the grain has to be quite large and under no circumstance should you use fine sand, beach sand or play sand which would make the potting mix way too heavy and airless when wet. Coarse sand creates a nice and crumbly potting mix, does not soak in water and allows air pockets to form.
There is no need to go overboard and buy all of these. 3 will do. Our potting mix includes a few though- composted pine bark fines, coir, minerals, pumice and coarse sand (NEVER use ordinary, fine sand). For those of you who like their mix extra fast draining lava rock could be a good choice as it is fairly chunky.
We would also add a wetting agent that retains water, so your plants have enough time to get a good drink before all the water drains away. Not everyone will agree with adding a wetting agent to a succulent potting mix, which is fine. The beauty of making your own is to produce something that YOU think is best for your plants. In our opinion there are 2 wetting ingredients that can be used.
Fine Coco Coir (our preferred choice)
Coco Coir is a made out of coconut fibres and shells. It is natural and durable product designed to help retain water and condition soil/potting mix. Coir is nearly ph (ph 6-6.7) neutral and is also sustainable and renewable.
This is another soil conditioner that can be used for water retention. It is slightly acidic, which is ok as succulents do not mind it slightly acidic with ph around 6.
Peat Moss is not a renewable source and is collected from peat bogs formed by dead plant material which have taken centuries to form. It also seems to decompose a bit quicker than coir. It is entirely up to you which one you choose to use in your mix. We have trialled both with no real difference made to our plants. We simply stuck with Coir because of its sustainability.
Slow Release Fertilizer
The last thing that we would add to the potting mix is slow release fertilizer. Although succulents will grow without any fertilizer whatsoever, a small amount of low nitrogen fertilizer will give them a bit of oomph and help them grow larger and faster. We prefer slow release as it is less time consuming than having to feed our many thousands of plants with liquid fertilizer. To learn more about fertilizing succulents see here.
A base can be many things but my recommendation is a potting mix with little nitrogen as succulents dislike it. An indoor plant potting mix or seed raising potting mix are a great choice. It will also mean the potting mix will not smell which is something to to consider if you're making a potting mix for indoor succulents.
A good base will add texture and essential nutrients and will constitute the majority of your DIY potting mix.
By far the easiest way to make a succulent potting mix is to get a base potting mix such as potting mix for indoor plants or seed raising potting mix. Next add 1 part pumice, perlite or lava rock (or a mix of the 3), a sprinkling of fertilizer suitable for succulents and voila, your succulent potting mix is ready.
The fertilizer should not be too nitrogen heavy either. Look for recipes where N (nitrogen) is lesser or equal to the other ingredients. The N-P-P (nitrogen-phosphorus-potassium) ratio should ideally be 8-8-8 or 10-10-10.
Mixing your own completely from scratch without using a store bought base is also not recommended as you will miss out on essential nutrients. I have previously tried different ways of DIY potting mix from scratch, just as a test, using nothing but raw ingredients and succulents i planted in it just did not do too well.
Some succulents varieties can be very sensitive to too much water and will benefit greatly from an extra gritty potting medium. We typically add a little more pumice and perlite to the potting mix for these plants and keep them under cover in a polytunnel where watering can be controlled.
If you just want to grow any random succulents for their looks then we would recommend getting a ready made potting mix and go for easy plants like Graptopetalum Paraguayens, Sedeveria Starburst, Sedum Clavatum or Crassula Ovata/Gollum etc. These succulents are extremely easy to grow and not too picky about their potting mix.
If, however, you have a bit of a collection of more rare and fussy plants such as Echeveria Romeo, Crassula Buddha’s Temple, Compton Corousel or new hybrids, you might want to try and make your current potting mix a bit more airy by adding a drainage agent.
Sometimes even the best potting mix in the world can't prevent a plant dying because they are living, breathing things that can die despite our best efforts. But such is life.
Investing in good quality potting mix will reward you with beautiful succulents. It can take time to find what is best for your plants, but it will all be worth it in the end.