TerraWiki

TerraWiki: The Terra Humana Lexicon

The TerraWiki is the open knowledge library of the Terra Humana Foundation on permaculture, ecological restoration and living with the land around the Mediterranean.

It is written for everyone who wants to heal soil, hold water and bring landscapes back to life, from a first garden to whole hillsides.

The knowledge is free to read and grows out of practice at Sa Medada, a slope in Sardinia where we test it step by step.

Not an open wiki; each entry is written and reviewed by the foundation.

articles: 168; articles
principles: 12; principles
learning panels: 74; learning panels
plant portraits: 30; plant portraits
pioneers: 16; pioneers
languages: 3; languages

Photo: Sa Medada, Jerzu

Where would you like to start?

Four ways into the TerraWiki, depending on what you are looking for today.

Painted landscape as a journey: a notebook on a rock and a seedbed, olive trees on a slope, a pond and a stream, a food forest with chickens and sheep, people at a long table and a wide plain turning green

Learn from the ground up

A journey through permaculture

12 chapters from the first look at the land to healing whole landscapes, with a travel passport and certificate.

Start the journey

Look something up

Glossary and search

Every term from A to Z, short definitions and full articles, in three languages.

Open the glossary

See connections

Mycelium of knowledge

All articles as a living network: what belongs together, and how one thing leads to the next.

Explore the network

Now in the garden

October

The spring of the south: the soil softens and planting begins.

Plant trees and shrubs after the first good rain.
Mulch after the first soaking rain, while the soil is moist.
Sow green manure and covers on moist soil.

The whole garden year

Or follow a short learning path:From soil to forest 7 stations Holding water on the slope 6 stations Trees that stay 7 stations

The essence

What permaculture is, at a glance

At the heart stand the ethics and the twelve design principles; around them, seven domains in which they work, after David Holmgren.

The twelve principles in the wheel

Tap a petal to see where permaculture reaches.

Domain 1 of 7

Land and nature stewardship

Where permaculture began: soil, water, plants and animals, cared for so that the land grows richer with every year.

In the TerraWiki

After David Holmgren’s permaculture flower. The spiral path leads from the personal and local to the shared and global.

Nine worlds of knowledge

Each world gathers the articles of one field. Here are the most connected ones; tap a world to see them all.

Soil and life

What works below the surface: humus, fungi, bacteria.

Water and slope

How rain is held before it runs off.

Food forest and growing

Food in layers, modelled on the forest.

Trees of Sardinia

Oaks, olives, macchia and the trees of tomorrow.

Nature in transition

Succession, restoration, and people as part of it.

Plant portraits

What already grows at Sa Medada: fruit, nitrogen fixers, trees.

Pioneers

People and places we learn from.

Closing the cycles

Water, nutrients, carbon, energy, material and seed: where cycles break and how to close them.

Designing with permaculture

Ethics, principles and tools: the journey through permaculture.

The people who paved the way

Mollison, Holmgren, Fukuoka, Maathai and others: what they discovered and what we learn from them.

What grows at Sa Medada

Portraits of the plants in our planting, from avocado to service tree: origin, needs, uses.

Project Eden · Sa Medada

Tested at Sa Medada

What these entries describe, we try out on our own slope. The captions say what each picture shows.

See Project Eden

Map: Pearl River Eco Design
Solar aspect map of Sa Medada from LiDAR data
Assisted Migration
At Sa Medada we are trialling banana, mango, avocado, cherimoya, papaya and moringa on a nearly frost-free south-facing slope.
To the term
Aerial view of Sa Medada with the property boundary
Ecological Succession
At Sa Medada all four life-span stages of a staged planting are occupied: fava bean and Bambara groundnut for a season, Tephrosia for a few years, coral tree and Leucaena for ten to fifteen years, Pacay and Inga edulis for the later canopy.
To the term
Young planting with mulch beneath an old olive tree at Sa Medada
Food Forest
At Sa Medada the food forest begins beneath olive trees that are already there.
To the term
View across the Ogliastra hills from Sa Medada
Nitrogen-Fixing Plants
At Sa Medada Tephrosia, around seven Leucaena, coral tree, Pacay, Inga edulis, Bambara groundnut and fava bean are in the ground, all so far without inoculation with root-nodule bacteria.
To the term
The Sa Medada farmhouse among old olive trees
Nurse Trees
Our first nurse at Sa Medada is a Leucaena: it is now two metres tall and shades two avocados.
To the term
The valley of Sa Medada near Jerzu, Sardinia, with olive grove and macchia
Service Tree
The service tree is the first tree we planted at Sa Medada, in 2024, deliberately on a very hot south-facing slope.
To the term

Recently added

Old wooden table on a Mediterranean hillside with tracing paper over a contour map, three drawn cards of a hen, a greenhouse and a water tank linked by red thread

since 21 Oct 2026

Designing with permaculture

Design methods

Bill Mollison's eight ways of working out a permaculture design, from listing what each element needs and gives to random assembly and zones and sectors.

A high alpine pasture in the Valais in late summer, brown cows grazing along a stone-lined irrigation channel, a village of dark larch-wood houses on the slope and snow-capped mountains behind

since 20 Oct 2026

Pioneers

Elinor Ostrom

American political scientist who showed how communities govern commons over generations. In 2009 the first woman to win the Nobel prize in economics.

Summer view over a Mediterranean mosaic landscape: an olive grove, a grazed pasture with cork oaks and a flock of sheep, pale gravel tracks and separate islands of dark green macchia

since 20 Oct 2026

Nature in transition

Fire-resilient landscape

A landscape shaped so that fire finds less continuous fuel, spreads more slowly and leaves behind land that can recover.

A village square in inland Sardinia in evening light, an open bakery with bread on wooden shelves, a carpenter's workshop with fresh planks and a market table with crates of vegetables

since 20 Oct 2026

Designing with permaculture

Local Currency

A local currency is a means of payment that is accepted only in one region or among the members of a network, alongside legal money rather than instead of it.