Succulents and cacti are renowned for their resilience and survivability. However, these plants will only thrive in specific soil conditions that mimic their natural habitat. Putting together the correct potting soil is essential for nurturing your plants. In this article, we will dig into the main soil mediums that we use at Living Desert Plants, and how to best use them for keeping your succulents and cacti happy and healthy.
Drainage, drainage and more drainage
The number one factor that is always mentioned with succulent and cactus soil mediums is drainage. But why is this so important?
Succulents and cacti are generally native to arid parts of the world, such as deserts. There are a few exceptions, but most of these plants do not receive much rainfall throughout the year. In order to keep them alive, it is highly important that their roots do not become waterlogged. For this reason, you have to choose your soil composition carefully.
Potting soil components for succulents & cacti
Perlite is a widely used component in horticulture that assists with soil porosity. It is light in weight, and does not hold moisture. It can be added to any potting soil or medium to increase the drainage capacity of the mix. We use this in the soil mixes for all our succulents and cacti.
Ibaraki Akadama is also useful in creating a soil medium for your plants. It generally only stays wet for a day, and then moist for a few days before drying out completely. As it is a clay soil, it is light brown when dry, and changes colour to dark brown when wet. This is a great indicator for when to water your plants again. It also makes it an excellent medium for any water-sensitive plants.
Hyūga Pumice is another good addition for soil mixes. It retains some moisture, which plants can utilize, but does not stay wet. It is also extra porous. This makes Hyuga pumice perfect for succulents and cacti that prefer a gritty, airy soil, and especially so for plants with sensitive roots.
Coco Peat is an excellent ‘base’ soil to use for plants that prefer a bit more moisture. While it does hold quite a bit more moisture than most other succulent mixes, it tends to dry out relatively quickly when mixed with perlite.
Slow release fertilizer is also a requirement for us in these mixes so that we do not have to worry about ‘feeding’ our plants every month. It is however highly important to only use very small amounts of it in succulent and cactus soil mediums. Using too much slow release fertilizer in the soil will cause root burn and damage the plant.
Potting soil composition for succulents
A mixture of 1:1 Coco Peat:Perlite works well for succulents like Adromischus, Aeonium, Aloe, Echeveria, Senecio, or any bulb species like Albuca and Ledebouria. This is not an exhaustive list, and coco peat can be used for many other plant species over and above the ones listed here.
However, it is important to note that coco peat does not suit the vast majority of cacti species (except for epiphytic cacti like Schlumbergera that prefer more moisture). It is also not suitable for succulent species like Conophytum (or any mesembs), nor does it suit Haworthia. For these plants, you will need something with more grittiness, which is where Ibaraki Akadama and Hyūga Pumice come in handy.
A mix of 3:3:3:3:1 coco peat (3 parts), perlite (3 parts), milled bark (3 parts), LECA(3 parts), and vermiculite(1 part) also works well for plants that require a bit more drainage than in pure coco peat, but still prefer a semi-organic mixture. It is a good ‘in between’ mix if you are not yet ready to swap over to a pure inorganic mix for your plants. It also works well for indoor plants and Clivia.
Potting soil composition for cacti & sensitive succulents
Ibaraki Akadama and Hyūga Pumice are pure horticultural gold for water sensitive plants. Both of these dry incredibly quickly, and are important components in soil mixes for highly water sensitive plants.
A mixture of 1:1:1 Akadama:Pumice:Perlite works well for all cactus species, and in particular Ariocarpus and Lophophora. It is also an excellent mix for succulents like Conophytum, Gibbaeum, Lithops, Haworthia, Gasteria, Pseudolithos and many more. Plants like Welwitschia, which are native to the Namib Desert, will thrive in this mix.
We have also experimented with planting cacti like Lophophora in 100% pumice and had great results, with extra strong root formation.
All of these plants need air pockets in the soil so that their roots can breathe, otherwise they run the risk of rotting.
Conclusion
Investing time in selecting the perfect soil is an investment in the long-term well-being for your succulents and cacti. By understanding their unique soil requirements and providing a well-draining soil mix, you create an environment where these plants thrive. The objective of replicating their natural habitat for optimal growth remains the most important, and should be kept in mind at all times when creating the perfect soil mix.
Written by Harry Lewis, succulent specialist & conservationist