Squeeze a handful of peat and it behaves like a sponge, draining freely yet holding water that roots take up at once: fossil organic matter built from plant debris in waterlogged bogs. Its slight acidity made it the classic soil-mix base, but nature replaces barely 2 inches of it a century.
Peat is a non-renewable resource, and peat extraction is highly regulated. Nature needs a full century to replenish a meager 2 inches (5 cm) of peat.
It has been traditionally used as the prime raw material for soil mix because of its excellent agronomic properties.
→ Read also: how to check what type of soil your garden is
It has the advantage of having excellent soil and air retention.
It drains very well, but also locks a lot of water in its sponge-like texture, where plant roots readily absorb it.
Lastly, it’s slightly acidic, which makes it a great choice for all types of heath plants (known to grow in bogs originally).
There are three major categories in which peat products fall:
Peat mining is a destructive practice. It destroys fragile environments that take millennia to recover.
To reduce this environmental impact today, you can use peat-free soil mix, or at least has a lower peat content.
These still boasts similar agronomic properties, but they’re produced from renewable sources instead.
→ For example, manufacturers add Brière black soil or also wood fibers such as Hortifibre.
Peat products sold for gardening fall into a few clear groups, and there are now renewable substitutes with much the same behaviour in a pot. Here is what separates them.
| Type | What it is made from | How far broken down | Why it matters in the pot |
|---|---|---|---|
| Blond peat | Sphagnum or peat moss taken from nature | Least broken down of the peats | Slightly acidic, airy and sponge-like, the traditional soil-mix base |
| Black peat | Decomposed sphagnum or peat moss | Broken down for much longer | The most degraded form of the same raw material |
| Peat-free or reduced-peat mixes | Brière black soil, or wood fibres such as Hortifibre | Not applicable | Similar agronomic properties from renewable sources, with no mining |
Choosing a peat-free or low-peat mix spares environments that take millennia to recover.
Peat contents depend on many factors, like the vegetation which produced it, the climate, and also how acidic the water is.
Essentially, peat contains water and poorly decomposed organic matter which accounts for 80 to 90% of dried ash weight. Only 10 to 20% of the peat is completely decomposed organic matter.
Carbon content can reach up to 50% of the total (dry) weight, which historically made it possible to use peat for fuel to cook or heat the house in regions where it was abundant.
Where does peat come from?
Today, production essentially comes from Europe (Northern Europe especially) and Canada.
