What is Maifan Stone? And why is it great for Cacti?
This is part of a series of articles we are writing that covers all the ingredients in our Cactus Soil mix.
Quick Explanation
Basic: Maifan stone is a type of rock/mineral that, in its powdered form, has been used in traditional Chinese medicine for quite some time. In horticulture, the granular form is gaining popularity as both a top dressing and a soil additive, especially in cactus cultivation and bonsai.
Advanced: Maifan stone is a silicate-rich, micro-porous, mineral aggregate composed primarily of feldspar (orthoclase and plagioclase), quartz, clay minerals (kaolinite and montmorillonite), and trace volcanic ash. It typically forms in hydrothermal or volcanic sedimentary environments and has a naturally high surface area due to its fine-grained, porous structure. It has strong adsorptive properties, making it capable of binding heavy metals, ammonia, and other ionic contaminants from water or soil. This suggests that Maifan stone likely possesses a moderate cation exchange capacity (CEC), owing to its mineral composition and adsorptive properties. However, we were unable to find any studies that report on CEC specifically when researching for this article.
Let’s explore what Maifan stone is, how it helps your cacti thrive, and how to use it properly.
What is Maifan Stone?
Maifan stone is a naturally occurring mineral rock composed mainly of silicate minerals such as feldspar and quartz, often found in regions with high volcanic activity. It contains a range of trace elements beneficial to plant and human health, including calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and selenium (Se), which are slowly released when in contact with moisture.
Chemically and structurally, Maifan stone features a porous matrix with a high surface area, giving it moderate water retention capacity and mild ion-exchange potential. While it is not as strongly ion-exchanging as zeolite, it still contributes to nutrient balance in the root zone over time.
It is most often golden/tan, beige, grey, or speckled in appearance, and is available in a range of granule sizes.
Benefits of Maifan Stone as a Top Dressing for Cacti
“Top dressing” refers to the layer of material placed on top of the soil in potted plants. For cacti, Maifan stone makes an ideal top dressing for a few key reasons:
Natural desert-y aesthetic: its matte golden tan colour is absolutely perfect for cresting a natural, desert pot staging.
Water control: It helps reduce rapid moisture loss from the soil surface without holding excess water. This helps avoid topsoil crusting and stops the soil from becoming hydrophobic.
Pest deterrence: A top layer of fine, inorganic gravel like Maifan stone can help to discourage fungus gnats and other moisture-loving pests from breeding on the soil surface.
Temperature buffering: It can help regulate surface temperature in pots, providing a slight buffer against sudden heat or cold exposure.
Benefits of Maifan Stone as a Soil Additive
Beyond its use as a decorative top layer, Maifan stone can also be integrated directly into your cactus soil mix. This is something we do ourselves in our own Premium Cactus Soil. There are heaps of benefits in doing so, including:
Slow-release trace minerals: Maifan stone gradually releases essential micronutrients like calcium, iron, and magnesium into the root zone over time, supporting healthy growth without the risk of nutrient burn.
Improved drainage: Its granular shape helps maintain soil structure and creates air pockets, promoting drainage and root aeration, key for avoiding root rot in cacti.
Moderate moisture retention: Maifan stone can hold small amounts of water within its porous structure, which is slowly made available to the plant. It is not as water-retentive as vermiculite or akadama, which, for cacti cultivation is mostly desirable.
Chemical buffering: It has mild pH-buffering qualities, helping maintain a stable and slightly acidic to neutral environment, which suits many species of cacti.
How to Use Maifan Stone in Cactus Soil
For top dressing, simply apply a 5–10mm layer of Maifan stone over your finished potting mix. Use a granule size of 2-4mm for young/small plants and seedlings, and a granule size of 5mm+ for larger plants. Avoid fine particles, as these can compact and block airflow.
As a soil additive, blend Maifan stone into your mix at around 5–15% by volume, depending on the needs of your specific cacti species and overall mix composition. Smaller plants or species sensitive to moisture may benefit from the lower end of this range, while more mineral-hungry or mature plants can handle more.
Maifan stone works well alongside other inorganic materials such as pumice, scoria, lava rock, and zeolite. It won’t break down or compact over time, making it a long-term structural and mineral support in your potting mix.
Where to Find Maifan Stone?
We sell small bags of Maifan stone in our online shop here. For larger quantities (or international readers), Maifan stone is available online or through many specialty bonsai and succulent supply stores. When buying, make sure the product is labeled as horticultural grade or food-grade (both are safe to use in pots). It should be clean, uncoated, and gravel-sized, not powdered or chunky boulders. Avoid any material treated for aquarium or industrial use, as it may contain additives not suitable for plants.
In Summary (the short version)
Maifan stone is a porous, mineral-rich volcanic rock that serves both decorative and functional roles in cactus cultivation. As a top dressing, it improves aesthetics, discourages pests, and controls moisture loss. As a soil additive, it contributes to better drainage, slow-release micronutrients, and mild water retention. Use it at a ratio of 5–15% in your cactus soil mix and add a thin top layer for best results.
