How Much Biochar to Mix with Soil? Ratios for Pots and Vegetable Beds
Last updated: 6 Oct 2026
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Too little does nothing and too much is not good either. Here is a practical mixing guide for small pots, large pots and vegetable beds.
Easy rule: 1 part biochar to 9 parts soil
- About 10% for pots.
- Start at 5% for beds and larger areas.
- Never more than 20%.
How much for each pot size
6-inch pot (about 2 L soil)
About 1 cup (200 ml) of No.1 granules.
12-inch pot (about 12 L soil)
About 6 cups of No.2 flakes.
Vegetable bed, 1 square meter
Mix 2-3 kg of No.2 into the top 15 cm, about half a 5 kg box.
Mixing steps
- Charge it: soak the biochar overnight in diluted liquid fertilizer, then drain.
- Measure and mix evenly through the soil.
- Plant and water well, then keep your usual fertilizer routine.
3 common mistakes
- Using too much makes soil dry out too fast.
- Adding it dry lets it pull water and nutrients from the soil at first.
- High doses for acid-loving plants: keep to 5% or less.
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