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Designing with permaculture

Use edges and value the marginal

Terra Humana editorial teamLast updated: 2026-10-168 min read

Transition from dense macchia to a flowering meadow along a moist channel, with wildflowers and a butterfly at the edge

In brief

The eleventh of Holmgren's twelve permaculture principles: life is richest where two worlds meet, and what lies at the margin is often worth more than it seems.

What the principle says

Use edges and value the marginal is the eleventh of the twelve design principles of David Holmgren. It turns attention from the middle of things to their borders. An edge is the place where two different systems meet: land and water, forest and meadow, soil and air, root and earth, a shady corner and a sunny one. Holmgren's principle starts from the observation that the most interesting things tend to happen at these meeting points, and that edges are often the most varied and productive parts of a landscape.

The principle has two halves. Use edges is a design task. A designer can lengthen edges, shape them and place them where they help: a pond with a winding shore instead of a round one, a bed with a curved border, a hedge that gives way to a strip of flowers and then to open ground. Mollison's rule of the edge effect says the same, and the herb spiral is its smallest example, with many microclimates packed into a few square metres.

Value the marginal goes further. In everyday language, marginal has come to mean of little worth. Holmgren disagrees. Marginal land, a steep slope, a rocky corner, a damp hollow, often carries the most diversity on a farm. Marginal plants, the ones called weeds, are often food, medicine or soil builders. And in a society, new ideas usually begin at the margins, tried by a few people before the many take them up. Permaculture itself began that way. Margins are reserves: they keep alternatives alive for the day when the main path fails.

Use edges and value the marginalLearning panel on principle 11 of 12: Use edges and value the marginal. Proverb: don’t think you are on the right track just because it’s a well-beaten path. Where two worlds meet: between forest and open land lies an edge in layers, from tree to shrubs and tall plants to grass. The forest holds species of the forest, the open land species of the open land, the edge species of both sides and some that live only there. They take food from one side and shelter from the other. A round pond and one with a winding shore have the same area; the winding shore has more edge. What to watch for: lengthen and shape edges, curved rather than straight; rich edges are gradual, not abrupt cuts; place rich edges where you pass often; value marginal land, a steep slope, a rocky corner, a damp hollow; plants called weeds are often food, medicine or soil builders. In the TerraWiki the principle works in the herb spiral, the food forest, the retention pond, the half-moon, the macchia and silvopasture. TERRAWIKI · LEARNING PANEL · PRINCIPLE 11 OF 12 Use edges andvalue the marginal Proverb: “Don’t think you are on the right trackjust because it’s a well-beaten path” 11 1WHERE TWO WORLDS MEET Forestspecies of the forestEdgespecies of both sides andsome that live only hereOpen landspecies of the open landfood from one side, shelter from the othersame arearound shorewinding shore: more edge 2WHAT TO WATCH FOR lengthen and shape edges: curved rather than straightrich edges are gradual, not abrupt cutsplace rich edges where you pass oftenvalue marginal land: a steep slope, a rocky corner, a damp hollowplants called weeds are often food, medicine or soil builders 3WHERE IT WORKS IN THE TERRAWIKI Herb spiralFood forestRetention pondHalf-moonMacchiaSilvopasture Basis: David Holmgren, Permaculture: Principles and Pathways Beyond Sustainability (2002)

The old saying: a well-beaten path

Holmgren pairs this principle with the saying don't think you are on the right track just because it's a well-beaten path. The popular way is not automatically the right one. A path becomes well-beaten because many people walk it, not because it leads somewhere good. In land care, ploughing slopes, clearing shrubland and draining every wet corner were well-beaten paths for generations, and many of the problems of eroded and dried-out land started there.

Many languages know the opposite advice as well. An Italian proverb warns that whoever leaves the old road for the new knows what he leaves behind but not what he will find. Both sayings are true, and together they describe the attitude of the principle: respect the old road for what it has proven, and still look along the edges for the paths nobody has tried.

How it looks in nature

Ecologists call the transition between two habitats an ecotone, and they have long noticed how rich it can be. The wildlife ecologist Aldo Leopold described the edge effect in his book Game Management in 1933: game animals were most plentiful where different types of cover met, because they could use food from one and shelter from the other. A forest edge holds species of the forest, species of the open land and some that live only at the edge itself.

Estuaries, where rivers meet the sea, are among the most productive places on earth, because fresh and salt water, nutrients from the land and tides from the ocean mix there. The same principle works on a tiny scale. The thin layer where fallen leaves meet the mineral soil teems with fungi and soil animals, and the narrow zone around each root, where the plant exchanges sugars for nutrients, holds far more microbial life than the soil a few millimetres away. Mycorrhiza is life at such an edge.

Honesty belongs here too. Not every edge is a gain. When a forest is cut into fragments, its new edges become hotter, drier and windier, and species of the forest interior retreat. Carolina Murcia's review of edge effects in fragmented forests made this clear in 1995. Rich edges in nature are usually gradual and grown, with many layers between one world and the next, not abrupt cuts.

Where the principle works in the TerraWiki

These pages show edges and margins at work:

  • Herb spiral: a small stone spiral that creates dry and moist, sunny and shady edges side by side.
  • Food forest: many of its fruit trees and shrubs are, by nature, plants of the forest edge, and the design copies that layered border.
  • Swale: a ditch on contour turns the meeting line of water and soil into a long strip where plants can root into moisture.
  • Retention pond: its shoreline is the edge between water and land, richest where it is shallow and irregular.
  • Half-moon and microcatchment: small rims that gather water from a bare area into a planted basin, using the edge between catching and growing.
  • Macchia: shrubland often written off as marginal, yet it holds soil, moisture and shelter on dry slopes.
  • Reconciliation ecology: field margins, roadsides and hedges give other species a place within land that people use.
  • Pioneer plants: the marginal plants of disturbed ground, which start the repair of a landscape.
  • Silvopasture: trees and pasture woven together, so that much of the land becomes edge.

At Sa Medada

Sa Medada is a slope in Jerzu, in Ogliastra on the east side of Sardinia, with a dry season lasting roughly from May to September. Its LiDAR wetness map tells a story of edges: a comparatively dry main area, and moister channels along the margins. On this land the edges are the moister places. Swales are planned; none has been built yet.

The steeper slopes are covered with macchia. To a conventional farmer that is marginal land, too steep to plough. Seen through this principle it is anything but worthless: macchia protects soil from erosion, keeps some moisture in the ground and shelters animals. The first tree of the project, a service tree, was planted in 2024 at one of the harshest spots, the very hot southern flank.

The previous principle, use and value diversity, asks for many species and connections. The next and last one, creatively use and respond to change, looks at the edge between today and tomorrow.

Frequently asked

What does use edges and value the marginal mean in permaculture?

It is the eleventh of David Holmgren's twelve design principles. Edges are the places where two different systems meet: land and water, forest and meadow, root and soil, sun and shade. Exchange is especially lively there, and so is life. The principle asks designers to use such edges and to shape them on purpose. Its second half asks us to value what lies at the margin, from neglected corners of land to plants and ideas that others overlook, because the margin is often where resilience and renewal begin.

What is the proverb for this principle?

Holmgren pairs it with the saying don't think you are on the right track just because it's a well-beaten path. The most common way of doing something is not automatically the best. Many good solutions in land care started at the margins, tried by a few people on poor land, long before they became accepted. The proverb invites us to look sideways at the paths nobody takes and ask what they might offer.

What is the edge effect?

The edge effect is the observation that the zone where two habitats meet often holds more species and more activity than either habitat alone. A forest edge shelters species of the forest, species of the open land and some that live only at the edge. Ecologists call such a transition zone an ecotone. Not every edge is good, though: when a forest is cut into small fragments, its edges become drier, windier and more exposed, which harms the species of the forest interior. Rich edges are usually gradual, not abrupt.

How can I create more edge in my garden?

Curved and wavy borders give more edge than straight ones on the same area. A pond with an irregular shore, a herb spiral, keyhole beds, a hedge with a strip of flowers in front of it, a path lined with low plants: each adds contact between different conditions. Every edge brings both shade and sun, dry and moist, shelter and openness close together. More edge can also mean more work, so it pays to place rich edges where you pass often and keep simpler forms further out.

How does this principle show at Sa Medada?

The LiDAR wetness map of Sa Medada shows a comparatively dry main area and moister channels along the edges, so on this slope the margins are the moister places. The steeper slopes are covered with macchia, land that conventional farming would call marginal, although macchia protects soil, keeps moisture in the ground and shelters animals. Swales are planned to hold more water on the slope; none has been built yet.

A tiny oak seedling in leaf litter, an old oak blurred behind itNext in this themeUse small and slow solutionsHolmgren's ninth permaculture principle: small and slow systems are easier to maintain than big ones, make better use of local resources and last longer.

Related terms

Herb spiral of stones with rosemary, thyme, sage and lavenderHerb SpiralA small raised mound built in a spiral, which packs several climates into a few square metres so that herbs with opposite needs can grow side by side.Dense maquis with mastic, myrtle, strawberry tree and rockrose on a rocky slopeMaquis (Mediterranean Scrubland)The dense, hard-leaved shrubland of the Mediterranean, from knee height to small trees, tough enough to hold ground that woodland has lost.Olive grove with flowering hedgerows, field margins, a pond and old treesReconciliation EcologyThe practice of fostering biodiversity inside landscapes people actively use, rather than only inside protected areas set aside from them.Target image (AI visualisation): the future food forest at Sa Medada, layered beds between the olivesFood ForestA cultivated woodland of edible and useful plants arranged in layers, designed to work like a self-sustaining natural forest.A level ditch along the contour of a dry hillside holding rainwater evenly, with a mulched earth bank of young trees below itSwaleA level ditch dug exactly along the contour of a slope, with the soil heaped into a planted bank below it, so runoff stops, spreads and soaks in.Small permaculture homestead with fruit trees, vegetable beds and a pondDavid HolmgrenAustralian environmental designer, born 1955, co-founder of permaculture and author of its twelve design principles; lives and works at Melliodora in Victoria.

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Further reading from around the world

Freely available sources we recommend for going deeper.

Sources

  • David Holmgren, Permaculture: Principles and Pathways Beyond Sustainability, Holmgren Design Services (2002, revised edition Melliodora Publishing 2017)
  • Holmgren Design, Principle 11: Use edges and value the marginal, permacultureprinciples.com (accessed October 2026)
  • Bill Mollison, Permaculture: A Designers' Manual, Tagari Publications (1988)
  • Aldo Leopold, Game Management, Charles Scribner's Sons (1933)
  • Carolina Murcia, Edge effects in fragmented forests: implications for conservation, Trends in Ecology and Evolution 10, pp. 58-62 (1995)
  • Milkwood, Valuing the marginal, milkwood.net (2020, accessed October 2026)

Last updated: 2026-10-16