top of page

Biochar instead of Perlite & Vermiculite

Most gardeners are aware of the benefits of using either Perlite or Vermiculite as an additive soil ingredient, but few understand that Biochar is the perfect alternative!

Many common potting soil ingredients serve the same use, such as Perlite, Vermiculite, Peat Moss, Bark, Wood Chips and Charcoal. Most are moisture retaining and more-or-less inert and can be used in the garden to prevent soil compaction, help to retain moisture and improve the soil's aeration and drainage. They’re also used in propagation of new plants and seed cultivations, as well as in indoor container growing, composting and on lawns.

There are both financial and ecological benefits to using charcoal in place of Vermiculite and Perlite. Both are becoming increasingly expensive, especially in the quantities used by commercial nurseries. Locally made charcoal can be cheaper and involves far less harmful production and transportation.

Vermiculite and Perlite have poor carbon footprints because their production involves heating them to extreme temperatures (Between 100 and 500 °C more than high quality Biochar) and they are imported over very long distances.

Our Biochar is made locally and as a byproduct (Often using wood that would otherwise be burn, chipped or left to rot - all releasing Co2 back into the atmosphere).

Biochar's carbon sequestration is almost permanent when buried in the soil, removing Co2 from the atmospheric cycle for hundreds of years and with the added soil benefits it brings there with.


Water Retention

Biochar has the ability to absorb water up to 6 times its weight!

Vermiculite and Perlite can absorb 3 to 4 times their volume in water.

Perlite and Biochar retain water because of their large surface areas covered with nooks and crannies. Yet they are the more porous than vermiculite and tend to allow water to drain much more readily and help improve soil aeration. Due to their large surface area they're good for plants that require higher levels of humidity, which is produced by evaporation off their larger surface areas.

Biochar, Perlite and Vermiculite are all good at retaining water, but Vermiculite acts more like a sponge and has a strong capillary action, so it can hold much more water and offers less aeration for the plant roots. This is good for more moisture loving plants.


Soil pH

Our Biochar has a pH level of around 7.5–8

(Some other forms of Biochar tend be more alkaline to varying degrees).

Perlite is neutral with a pH of 7.0–7.5, but it has no buffering capacity and contains no mineral nutrient.

Vermiculite has a pH of 7.0–7.5.


Mineral Adsorption

Using Biochar or Vermiculite as growing medium enables plants to more easily absorb nutrients such as Ammonium, Potassium, Calcium, Magnesium and Phosphorus necessary for vigorous growth. Both absorb nutrients and then later release them to the plants when required.

Perlite however doesn't absorb nutrients.



Biochar can be thought of as a habitat not a fertiliser, because it serves as a carrier for plant nutrients, making them available as and when the plants need them via microbial symbiosis.

Biochar needs to have the right pores accessible and habitable to microbes. Too small or powdered and these pores don't exist, too large and they are inaccessible. We recommend between 0.1 and 5mm

The thermal process which produces biochar is called pyrolysis which involves burning at very low oxygen levels. Our Biochar is made from British Hardwood which is pyrolysised at around 750°C. (Lower quality Biochar can be made from many plant products and at different temperatures 300–1000°C).

During this process many trace elements (over 50 metals) crucial to plants are adsorbed to the carbon structure, preventing them from leached out, yet keeping them accessible to microbes and plant roots.

Fresh biochar may adsorb nutrients in the soil, causing a temporary negative effect on plant growth. This can be avoided by Enriching the Biochar before use, allowing it to soak up vital minerals and nutrients (as well as microbes) which are all later released to the plants.

An added benefit is that by adding 10–30% biochar (by volume) to your compost to enrich it, can help speed up the composting process by around 30%. The resulting compost is also a highly efficient substitute for peat in potting soil.

Biochar helps to absorb excess fertiliser, preventing run-off into water systems, while retaining the nutrients in the soil for the plants to access. If nitrogen fertilisers are applied in the wrong amounts or quantities some bacteria act on it making Nitrous Oxide which is over 200 times more effective at trapping heat in the atmosphere than Co2.



Vermiculite is made from hydrated Magnesium Aluminum Iron Silicates which are mined and processed from rocks containing Biotite and Iron-bearing Phlogopite. This is then heated to 800–1100°C causing it to expand.

Vermiculite is very popular due to its extremely low density, thermal conductivity and high water retention. The most commonly used sizes of Vermiculite are: 0.1–2, 2–4 and 4–8mm.

Large commercial Vermiculite mines currently exist in the USA, Russia, South Africa, China, and Brazil. Commercial Vermiculite is mined and processed from rocks containing large mineral crystals. When these rocks are exposed to the weather, they decompose allowing water and various other chemicals to react.

The manufacturing process consists of two operations. Rocks containing Vermiculite are dug from a huge open pit in the ground which are then ground up and transported for extraction (In some Vermiculite ore deposits, there may also be certain amounts of various forms of asbestos!). This is done by either froth flotation, gravity separations or electrostatic separation. Next the Vermiculite is then heated to produce the expanded granules. This process is often done at a different location, a long distance away.

It was estimated in 1999 that the world had approximately 55 million tons of Vermiculite reserves. Worldwide vermiculite production was about 404,000 tons in 2016 and that amount is still rising.



Perlite is a glassy rock formed when lava spews from a volcano, it has a very high silica content which is mixed with 2–5% water due to its rapid cooling. When heated to 870–1100°C the combined water in the perlite is converted to a high temperature gas, causing it to expand 4–20 times its original volume forming a highly porous and lightweight material.

Perlite is usually between 0.1–2 and 1.5–3 mm in diameter. The various grades differ in their physical characteristics and uses from potting soil mixtures, standalone growth mediums and soil enhancers.

Around 70% of Perlite is produced along the Aegean coast in Turkey, with an annual production of about five million metric tonnes. It's also produced in other countries all around the world like America, China, Greece, and Italy. It's estimated that there are about 700 million tonnes of perlite reserves in the world.


Our Conclusion

Vermiculite & Perlite Cons;

  1. Perlite and Vermiculite both involve destructive mining.

  2. Their production involves many fuel consuming processes.

  3. They need to be shipped long distances from their source to you garden.

  4. This production and transportation adds Co2 to the atmosphere.

Biochar Pros;

  1. Our Biochar is made locally and so needs less transportation.

  2. It is sustainably produced.

  3. Beneficial to the local environment and wildlife.

  4. Preserving our native woodlands and foreign forests.

  5. It stores Co2 in the soil for hundreds of years.

  6. Better for your plants and soil encouraging microbial activity



Recent Posts

See All


bottom of page