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Biochar Granules, 0-13 mm grade

Our larger pack sizes will typically save you 20% to 40% on a per Kg basis. Our prices include free courier delivery to mainland regions. P&P on other websites can add £8-10/item. 

What is Biochar

Biochar is a form of charcoal-carbon made from wood by pyrolysis, ie combustion without oxygen. Good biochar improves soil structure, tilth, aeration, water-holding capacity and nutrient retention. These properties lead to improved soil health and plant growth.

Why use biochar

Biochar made from wood supports enhanced microbe and fungal growth. These microbes live in the biochar pores and access the stored nutrients. The microbes form symbiotic relationships with plant root hairs – moving nutrients to the roots in exchange for sugars (food) from the roots. There is growing evidence this root zone activity stretches beyond nutrient transfer. The exact mechanisms are not fully known, but it appears a community of mutual defences against pathogens and diseases is created which results in enhanced plant vitality and disease resistance.  

Our internal testing and analysis have led us to only use biochar made from wood. We grade and sieve our biochar particle sizes to enhance soil microbiology, soil aggregation and soil tilth.

Biochar features

  • Improved plant and vegetable growth (We are confident biochar will deliver +20% plant growth) 
  • Improved water retention
  • Improved nutrient supply to roots
  • Decreased nutrient run of
  • Support for microbes and AMF (mycorrhizal fungi)
  • Supports the formation and stability of colloidal humus
  • Improves soil tilth

Read more in our biochar article

Environmental benefits include:
  • Carbon capture by locking carbon in the soil for hundreds of years
  • Offset your carbon footprint - 1Kg biochar equals approx 2.0 Kg of carbon dioxide 
  • Reduced NOx and methane soil emissions

Where to use biochar

  • Planters
  • Raised beds
  • Allotments
  • Lawns
  • General gardens
  • Add to compost

How to apply biochar

Raw biochar needs to absorb nutrients and develop root zone relationships - this can take 3-6 months. This ‘lag’ period can be solved by soaking (charging, activating, enriching) your biochar before adding it to the soil.  The best method is to add biochar to your composting process and then add the biochar/compost mix to your soil. You can also soak the biochar in a liquid fertiliser before adding to the soil.  For customers who want to buy a ready-to-use activated biochar, please see our Biochar Super Compost (SF60) soil improver or Biochar Multi-purpose compost (SF40).

The most powerful biochar benefits involve interactions with the root zone. It follows the best place for biochar is in the root zone. Our recommendation is to dig it when planting (eg seed drills, tree holes or when cultivating the soil. This is not always possible (nor desirable if following a no-till regime!) and biochar benefits have been shown when used as a top dressing or when lightly hoed into the top few centimetres of soil.

Should I use powder or 0-13mm granules?

The SoilFixer 0-13mm grade biochar achieves the best balance of particle size ratios for use in soil. Typically there are 20% <2mm, 50% 2-8mm and about 30% 8-13mm. Trommel sieves allow a small number of long thin bits to pass, there will be a few bits longer than 13mm).

We do not recommend fine (amorphous) biochar powder as they do not have the macro-pores needed by soil microbes.  We also advise care when using large granules (>13mm sieve) because the volume of surface pores available to the soil microbes is very low and large particles negatively impact soil aggregation (ie tilth). (Read more in our biochar blog).

How much biochar should I apply to the soil?

Apply 1 Kg/m2 (one kilo per square metre)

This approximates as 5% by volume, but it does depend on the soil depth.   For more detail on application rate calculations by area, volume and weight and tips on how to make your biochar budget go further, please visit the application ratio blog


Our biochar is 100% made of arboricultural arisings (tree and hedge trimmings, prunings and trees) and is certified to the EBC certification standard. Pyrolysis production (heating without oxygen) is undertaken in advanced kilns. You can read why this matters to the environment and your carbon footprint via our blog.  

Volumes and Weights

Please note biochar absorbs water and the exact water content varies by season. Hence we sell based on litres with an approximate Kg weight. 20 litres is approx 10Kg and 40L approx 20Kg. Our biochar has approximately 40% water content. If you wish to compare prices, always compare Volume (litres) or ensure you work back to £/Kg of dry biochar (ie adjust for moisture content).

How to use / specification
How to use Mix 1-10% by volume into raised beds, containers and around plants to improve crop and plant growth. Please note all biochar should be activated before use - for more read our biochar and SF60 FAQs
Pack size 10, and 20 Kg sacks 2 m3 bulk bags
Particle size 0-13 mm, 100% passes through 13 mm mesh sieve. (Note the nature of square mesh sieves is that some long-thin particles bigger than 13mm pass through.
Weight 10 Kg sack (20 litres), 20 Kg sack (40 litres) 2 m3 = 1000 Kg (+/- 50Kg)

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Biochar Granules (0-13 mm)

  • Product Code: BC 0-13
  • Availability: In Stock
  • £25.80

Available Options

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