The substrate
On this page I present to you different compound substrates that I use and the different possibilities to adapt it. There is as much substrate as cactus collectors. Experience will tell you which one works best for you. A substrate in a clay pot will dry faster than in a plastic pot, just as a pot with a large volume will retain humidity and can be enriched with draining elements.
A draining and more mineral than average substrate is important for hardy cacti since winter humidity is the number one enemy. My choice fell on the cactus soil from Hakaflor.
Hakaflor cactus soil
This is the substrate I use for all my plants now. It is very mineral (volcanic lava, clay, vermiculite, pumice stone and pumice sand) but contains organic matter composed of coconut fiber. According to the experience of Hadorn owner of Hakaflor, a mineral substrate used pure is not ideal. Since using this substrate I have seen excellent growth and healthy roots. If you don't want to start making a homemade substrate, I recommend this one
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It can be purchased at Hakaflor in Sirnach and at the Garden Center in Lavaux as a 7.5L bag.
Lechuza Pons
This 100% mineral substrate is sold at the Coop, in Hornbach and Obi. Its interest is that it contains pumice, lava rock and zeolite. It stores water while draining.
I used it for a few plants but added 5 to 10% potting soil to add organic matter.
One of the disadvantages is that it contains slow-release fertilizer balls. I prefer to dose my fertilizer myself.
Organic matter
Rich in nutrients, organic matter also called humus is the result of the decomposition of plant matter. The soil provides the nutrients needed for plant growth. It allows the growth of organisms and fungi (mychorizal symbiotic relationship) important to the good health of plants and soils.
The pumice stone
The pumice stone works wonders. Very light, it offers good aeration of the substrate and allows the roots to develop thanks to its water retention capacity. Pure pumice is ideal for cuttings too. The seedlings that I made in a homemade substrate of 50% pumice, 20% organic (compound) and 30% gravel gave me the best results in terms of growth and roots. It is available in different grain sizes. Choose an average.
Available from German suppliers like Uhlig or Kakteen Haage.
Volcanic rock or pozzolana
Volcanic rock, also called pozzolan, is interesting for its ability to retain water and humidity in a substrate. I use it for my Pterocactus as they like to have wet feet and for some Austrocactus growing in volcanic rock in the habitat.
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You will find it in any garden center. There are different grain sizes. That of 8 to 16mm seems to me the most suitable.
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Diatomaceous earth
I just added this substrate also called kieselgur to my mixture after a discussion with Michael Kiessling on his mixture. It is ideal for the cultivation of cacti and succulents as additives to the substrate. The insecticidal action of diatomaceous earth helps prevent the appearance of pests in the roots such as lice or scale insects.
The homemade mix
The homemade substrate is ultimately an assembly that you make according to your budget and what you have on hand.
Garden soil, vegetable garden soil, pumice, volcanic rock, concrete gravel or even sand for children's sandpits, everything can be assembled.
My rule is at least 60-70% mineral and avoid proportions of sand greater than 10-20% so that the substrate does not harden. The rest depends on your desires and needs.
