Glass Jar Garden

Soils and layers

Horticultural charcoal as drawn in the simulator

Horticultural charcoal

Chunky wood charcoal that keeps the soil fresh for decades.

What the simulation uses

Holds water
25 % by volume
Water it keeps after draining; the rest runs down to the drainage.
Pore space
72.5 % by volume
Room for air and water between grains; low means roots suffocate when wet.
Weight
360 g/L
How heavy a litre is.
pH
7 to 10 pH
How acid it keeps the soil.
Mould risk
none
How much fresh food it gives white mould; high-risk soils fuzz over in the first weeks.
Breaks down in
100 to 1000 years
How long it lasts before rotting down to fine soil.
Nutrients
low
Plant food it brings.
Presses down to
97 % of its loose depth
How far pressing can pack it, keeping its weight.

Description

Unlike activated charcoal, these are plain wood charcoal chunks. Mixed into soil they add structure and gentle filtering, and fresh pieces raise pH slightly. They will outlast everything else in the jar by centuries.

Also called lump charcoal, biochar, orchid charcoal.

Estimated, where sources were thin: CEC develops only after ageing; water holding estimated.

Sources

Grow it in a jar