Soil Fixer Biochar Granules (0-13mm)

🪨 Type: Inert Structural Media
Contains no nutrient content by design — this is texture, drainage, and aeration, not food. Meant to be used as a standalone medium, a mix-in component, or a soil amendment.

SoilFixer Biochar Granules (0-13mm Coarse Grade)

A permanent, natural soil improver that locks in structure and microbial life for centuries, not seasons — SoilFixer's coarse 0-13mm biochar granules are Soil Association approved and European Biochar Certificate certified, making them a genuinely safe, long-term amendment for edible crops, ornamental beds, and large potted plants alike.

Particle Size Breakdown

Approx. 20% <2 mm

Approx. 50% 2–8 mm

Approx. 30% 8–13 mm

Trommel sieves may allow a few long, thin bits to pass, so some particles may slightly exceed 13 mm.

We do not recommend using fine biochar powder (amorphous biochar) because it lacks the macro-pores needed by soil microbes. We also advise against using very large granules (>13 mm), as they offer low pore surface area and can negatively affect soil aggregation (tilth).

Good For Large Pots, Trees & Shrubs — Not Small Pots

This coarse grade genuinely suits large houseplant pots, potted trees and shrubs, and anything with an established, sizeable root system — the bigger granules work themselves into a bigger volume of soil without issue. What it isn't right for is small pots, seed trays, or lawns, where the same coarse structure gets in the way rather than helping; those jobs want a finer 0-8mm grade instead.

How Much Biochar Should I Apply?

Apply 1 kg per square metre (1 kg/m²)

This is roughly equal to 5% by volume, although it depends on soil depth.

Volumes and Weights

Biochar naturally absorbs water, and moisture content varies with the seasons. That's why we sell by volume (litres) and provide an approximate weight.

20 litres ≈ 10 kg

40 litres ≈ 20 kg

Our product contains approximately 40% water by weight.

If comparing prices across suppliers, make sure you're comparing volume (litres) or adjusting prices to reflect £/kg of dry biochar.

FAQs

Is biochar safe for vegetables and edible plants? Yes. SoilFixer biochar is Soil Association approved and European Biochar Certificate certified, making it completely safe for vegetable gardens and edible crops.

How long does biochar last in the soil? Biochar is extremely stable and can last hundreds to thousands of years in soil. It's a permanent soil improvement, not a short-term fertiliser.

When is the best time to apply biochar granules? Biochar can be applied at any time of year. Autumn and spring are ideal — autumn allows it to settle over winter, spring gives immediate benefit for the growing season.

What is the difference between 0-8mm and 0-13mm granules? The 0-13mm coarse grade is ideal for borders, trees, shrubs, larger garden beds, and large houseplant pots. For small pots, seed beds and lawns, use a 0-8mm fine grade instead.

All bags have been decanted from bulk bags into clear/plain plastic bags.