Although succulents are pretty hardy, keeping them is not always easy. It repeatedly happens that succulents and cacti drop their leaves or suffer from root rot. The cause is often the substrate.
In this article, you will learn how to mix the optimal substrate for cacti and succulents and what you should look for in purchased mixes!
The natural site of a succulent or cactus
Before we get to the actual mixing and the effect of individual ingredients, we should look at how succulents grow in nature. There is no trace of the rich dark substrate we know in their natural locations.
Before we get to the actual mixing and the effect of individual ingredients, we should look at how succulents grow in nature. There is no trace of the rich dark substrate we know in their natural locations.
So now, when we go to our substrate mix, we should try to copy the conditions of the natural site.
What the mix should contain
The optimal mix for succulents and cacti should include mineralic and organic components.
By organic components, I mean primarily plant parts that were previously alive and have now (partially) decayed. That includes, for example, coco soil or peat. Organic components serve mainly as nutrient suppliers and water reservoirs.
In contrast to the organic components are the mineral components. They have “never lived”. Rocks and glasses, such as perlite or lava granules, are various examples. Mineral components give the mix the necessary structure as well as drainage.
Therefore, most of our mix will consist of mineral components. However, since cacti and succulents are still plants, we will also mix in organic ingredients.
The Cacti and Succulent Soil Recipe
In the following recipe, we work with parts. Each part is the same size. If you are using a bowl, each bowl represents one part.
The ratio for the mix is 2:1, which means for every part of organic material added, two parts of mineral material are added.
A plain mix, which is suitable for most succulents, consists of
- 2 parts perlite*
- 1 part peat-free green plant soil
For cacti, the mix can even be as follows:
- 4 parts perlite*
- 1 part peat-free green plant soil
Perlite provides the necessary drainage. Since it is dimensionally stable, it loosens the mix and allows air to circulate. It can also temporarily store water, as well as nutrients.
On the other hand, green plant soil stores more water and is rich in nutrients. Because of its fine texture, green plant potting mix alone would be too tight around the roots and prevent air circulation.
Organic options
Of course, green plant soil is not the only option for organic material. Instead of or in addition to green plant soil, you can also use worm humus, compost, and coco soil.
For more information on substrate ingredients, check out our detailed substrate post.
Mineral options
Perlite can also be supplemented or replaced with several other mineral options:
- Pumice
- Lava granules
- Coarse sand (be sure not to use beach sand because of the salt)
- Gravel
- Decomposed granite
You can find more information about the ingredients of substrates in our extensive substrate article.
Ingredients you should avoid
In addition to the right ingredients, there are also ingredients that you should not add to your mix. These include vermiculite and peat.
Vermiculite
The mineral vermiculite is a rare layered silicate. It is pretty light and breaks easily. Due to its large surface area and structure, it stores water well.
Since cacti and succulents like relatively dry substrates with good drainage, you should do without the water reservoir. Otherwise, root rot may occur.
Peat
It would be best if you avoided peat not only for the sake of the environment. Dry peat is hydrophobic, which means that it is water-repellent.
So when we water the succulent or cactus, the water will run off the surface instead of seeping through the substrate. In addition, the peat does not serve as a temporary water reservoir.
In some cases, this can cause succulents and cacti to die of thirst despite regular watering.
Adjust the mix according to your conditions
Of course, the mix described above is not set in stone. On the contrary! Depending on the location conditions of your plants, you should adjust it.
For example, if you keep your plants in a relatively small room with cooler temperatures and rather high humidity, you can increase the amount of mineralic ingredients.
If your plants are in full sun in a south-facing window, you can increase the organic content to retain moisture better.
You probably won’t find the perfect mix for you and your conditions online but through trial and error!
What to look for in store-bought cactus and succulent soils
You can come across a wide selection of succulent and cacti soils online and in garden centers and hardware stores. However, not all cactus and succulent soil are equally suitable for plants.
Like food, soils have an ingredient list on the back of the package. Here you will find the ingredients sorted by quantity contained.
The first ingredient should be of mineral origin. Ideally, it should have a coarse, pebbly structure. The second or third ingredient should be the first organic ingredient.
You should not use soil with peat for succulents.
If you have found a suitable potting mix but are still unsure whether it is ideal for the succulent or the cactus, you can test it.
Take the pot in which the plant will be potted and fill it with the substrate. Then water it as if you were watering your plant. Now place the planter in the place where the plant will stand. If the substrate is still damp after two to three days, you should mix in more mineral components.
The alternative to conventional substrates
Seramis is a good alternative, especially for cacti. The clay granulates not only allow enough air to circulate but also hold very little water and have excellent drainage properties.
Since this is a purely mineral substrate and almost a passive hydroponics, you will have to keep adding nutrients via fertilizer.
Due to the rapid drying, you also have to water regularly. With cacti, however, these intervals are pretty generous.
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