Doubts about the design principle of "edge"

I've understood that the principle of "increase edge" comes from the observation that intersections of biomes, say the forest edge or a lake shore, have a higher biodiversity. The principle is often quoted to promote mandala gardens or keyhole designs.

However, I think that people forget that these can interfere with efficiency of workflow. It is complicated to navigate a wheelbarrow along meandering paths, and mandala gardens may do well in the tropics, but how efficient are they in sloping sunlight common closer to the poles?

On the other hand, diversity brings resilience... how to resolve this?

Hi Susan, I feel the same way, coming from more of a market gardening perspective, where efficiency is so highly valued. I think there's a balance between work efficiency and diversity that will differ for everyone depending on what their design goals are, and I agree - having a lot of meandering paths and mandala gardens may not be the best option for everyone, especially as you get out into Zone 3 designs where you may have a lot of work to get through at certain times of year, and need to be able to get a cart or other equipment through.

That said, "edge" is a very diverse category and it can apply in a lot of different ways depending on your scale. I would consider all of the following to be an "increase in edge":

A grain farmer reducing erosion by strip-cropping, planting alternating strips of maize and grass along a slope

A sheep rancher building up perennial hedges, including food plants for people and birds, instead of just plain wire fencing

A pig farmer including both forest and pasture in a fenced-in paddock so the pigs can take advantage of the shade and mast while also uprooting sod for a later planting

A vegetable farmer putting a pollinator garden in the odd bits of space along the field edges and over her irrigation lines rather than just mowing them

A suburban homeowner planting raspberries along the edge of her property, screening her view of the neighbors and providing them both some tasty food

An urban IT professional, going out of his way to bike through different neighborhoods on the way to work rather than always taking the same path

I think the principle is probably given as "increase edge" because most of us have efficiency so beaten into us that it helps to push the conversation the other way. But if you're going to repeat the same task 200 times a year, I would never advise you to put an obstacle in your property that doubles how long that task takes.

I have almost straight paths between important locations on my homestead, and meandering paths off those to less important spots.  Most paths and trails are approximately on contour, except short side trails, because we have huge erosion potential here.  I'm currently working on multiple hiking trails on contour on our hill, which are providing lots of edge and (I hope) erosion control.

My Kitchen Garden, which is meant to be a relaxing space for wandering in search of dinner, has curving, intersecting paths around polyculture beds.

The OP has raised an excellent point in that not all permaculture techniques, even the popular frequently-touted ones, are wise choices for every permaculture design.  Different local conditions call for different solutions.  Compromise and balance are always essential parts of the design process.  I think Dave Ruggiero's post expresses this very well.

I offer a personal case study, since I feel this very acutely on my own property...  Consider that one of the most easily observable distinctions between a conventional ag operation and a permaculture property - in addition to scale, monocrops vs polyculture, etc. - will likely be that the conventional ag operation will have taken steps to remove all texture from the land, making everything as flat and straight as possible.  Why?  Because this facilitates use of machinery.  Whereas the permaculture property likely has texture added to the land: berms, terraces, hugelkultur, swales, plantings following contour, etc.  Why?  Because they serve to increase edge, foster micro-climates, capture water, etc.  Not to mention that they often look cool!  The permaculturalist has the luxury of utilizing these techniques because (s)he is designing around plants and animals and people, not around vehicles.

Well, it so happens that I garden from a wheelchair.  On my property, the gardener is a vehicle.

Even while I live in a fairly humid climate, we still get long dry spells during the (very hot) summers - I am just right now enjoying my first significant rains in two months!  And I started from bare dirt, having needed to move a lot of earth around for my building requirements.  So while the dirt moving equipment was still here, it would have been very convenient and desirable to install a swale or two.  Instead I worked hard to make everything as flat (well, gently sloping at least) and smooth as possible, or else I would be unable to navigate my own property.

Necessary compromise.  But that doesn't make the principles of increased edge and micro-climates and water capture less valid or less important to me; I just find it necessary to pursue them as best I can through other means.  To conserve water, for instance, I have chosen a shadier model of food forest than I might have done otherwise, focus on thick mulches where I can, installed ponds for passive irrigation (i.e. increasing morning dew), am still striving to improve my soil, etc.  Of course, a lot of these things I would have been doing anyway just because they are generally sound techniques.

Similarly, while I am a big fan of the principle of increasing edge, that doesn't mean that any particular technique that might fall under the "max edge" category is a must-have for every property.  Pick and chose as you like and as your conditions and needs dictate.  There are many ways to design diversity and edge into your property - most that you are likely doing already - while also having straight paths.

P.S.  I never really thought too much about keyhole garden design as a technique for increasing edge, though I can see how it serves that principle, too.  I had understood the prime advantage of keyhole beds to be that they maximized the square footage under cultivation within any given area compared to straight paths.  Is this not so?

Matthew Nistico wrote:

P.S.  I never really thought too much about keyhole garden design as a technique for increasing edge, though I can see how it serves that principle, too.  I had understood the prime advantage of keyhole beds to be that they maximized the square footage under cultivation within any given area compared to straight paths.  Is this not so?

This is what I understood keyholes' primary purpose to be, as well.

I hate them, in most circumstances. The end of a row, sure. A weird little corner, great. Large ones, repeated en masse in areas meant to be more productive than decorative... no thanks! Extra walking and fussing about navigating curves with wheelbarrows etc, leading to people making new paths. Not great.



Edge is expensive to create, if it involves a ditch, or a fence, or a hedgerow, or a hugel, or... Whether in hours or dollars or litres or years, there is a cost. And, it can also be expensive to maintain.

I am spending quite a bit of time thinking about where various edges should go. How many extra $12 fenceposts do I feel like spending, to follow a rise or a curve? How much extra excavator time, to make a meandering S-shaped ditch?


One place where I do see potential is field corners, in areas that will see machines. My fields are small, so a nice little patch of trees following a comfortable turning radius in each corner, could really add up to quite a few trees. It could be inside the main fence, and protected with electric when grazing animals should stay out, but still available for inclusion when the trees are robust enough, and eventually there will be mast for critters to enjoy as well as shelter...

My property is a somewhat square polygon but with a ravine going down most of the middle. the ravine starts about 80 feet from the North end at about the mid way point and gets too steep to disturb pretty quickly, else I'd likely lose what little top soil there is on those slopes. That leaves my usable area as a "u" shape. Sort of a mixed blessing. The perimeter fence is easy. Four straight sides. But fencing off the ravine and doing cross fencing is going to be a pita. The ravine will be left as forest, plus three sides of my perimeter are forest. My perimeter is 3250 feet but I'll likely end up with 5-6000 feet of edge. We're getting goats in the Spring and they love the diversity of edge. The trick will be to make sure they don't kill that diversity, else I'll end up with grass to trees. Of course freshly cleared land bursts with diversity for a while as pioneer plants pop up and I think it tends to taper off after that. Would probably be a good area for clay seed balls. I could harvest seeds from the gazillion miles of gravel roads we have here, once I know what they like.

There are a few other spots that are too steep to clear with a machine but I can thin it by cutting trees down with a chain saw. These areas are not too steep to let he goats on, as long as it's not the rainy season and once thinned to let sun in, they will be similar to edge in diversity.

My cross fencing and grazing frequency are going to be insane to keep things diverse but I don't want it to end up like most properties that run goats. Pasture. Good for cattle and sheep but not for goats.  (I might not be getting as many as I had planned)

I do believe in edge though. While perusing the descriptions of plants and small critters on our State's conservation website, I see a lot of mention of edge, especially with bird habitat but also with many native plant species so there is something to it.

John Pollard wrote:My cross fencing and grazing frequency are going to be insane to keep things diverse but I don't want it to end up like most properties that run goats. Pasture. Good for cattle and sheep but not for goats.  (I might not be getting as many as I had planned)

Ah, you are a wise man.  Goats are useful livestock, and a good choice for some habitats (edge!), but they can have a very big impact on the landscape.  Better to run them in smaller numbers and keep them moving.

There are a couple of goat dairies near to me that feature large pastures, some highly denuded.  Not at all prime goat habitat.  Thus the dairies basically functioning as feeding operations.  In one case I know for sure, because I've talked to the owners extensively, that they started with forest and let the goats clear the trees completely over years.  I can only guess that they believed this was an improvement.

Have you considered a mixed flock?  As in, rotating a small number of goats along with other species of livestock, either together or in sequence, that will utilize different aspects of the habitat?  I don't know much about this practice, but I know that it can work (see Joel Salatin's example), and it might be a good way to get the most out of your property while maintaining a sub-standard sized goat herd.  I would guess that small omnivores, such as poultry and/or muscovy ducks, might thrive in the same habitat as goats.  They were both jungle species, originally.

Dillon Nichols wrote:

Matthew Nistico wrote:

P.S.  I never really thought too much about keyhole garden design as a technique for increasing edge, though I can see how it serves that principle, too.  I had understood the prime advantage of keyhole beds to be that they maximized the square footage under cultivation within any given area compared to straight paths.  Is this not so?

This is what I understood keyholes' primary purpose to be, as well.

I hate them, in most circumstances. The end of a row, sure. A weird little corner, great. Large ones, repeated en masse in areas meant to be more productive than decorative... no thanks! Extra walking and fussing about navigating curves with wheelbarrows etc, leading to people making new paths. Not great.

Your point is well taken, especially about people creating their own paths where the ones given to them prove less practical.  To me, that seems the ultimate proof of concept.  There is a practice in urban planning where you build no sidewalks or pathways for a year or two, and instead let the people wear their own paths, which they will quickly do with definite consistency along the quickest and most convenient lines.  Then you follow up with the pavement where their feet have indicated.

This is a perfect example of my original point: tailoring the design process to the needs of the individual property and property owner.  Personally, I love keyhole beds.  If I were designing a family small-holding, I would be sure to utilize many.  But if I were designing a market garden operation, perhaps I would decide that aesthetic appeal and maximizing square footage under cultivation were less important than smooth and efficient flow of people and materials, and keyhole beds would be a feature that mostly get skipped.

I think of the productivity of the edge as coming from something on each side of it.  In the case of this thread, growing space and travel space.   So design criteria should be Convenient travel and access to the growing area.  Wide path, narrow path or keyhole a re just variations for matching the needed travel and access.  More productivity can be gained by stacking functions.  The path can be a place for composting. The water edge a source of irrigation.  The transition a place for supporting or complementary plants.
So when drawing a line on paper or in the dirt think of the functional possibilities on both sides.

In my experience edges impose themselves even when you don’t want them to, and so does diversity! I have a large-ish garden, the bones of which were set eons ago by my mother.  Definitely more rectangular than I might wish, but I find it hard to change things because a) it’s been the same for so long it’s kind of bossy b) moving soil and perennials etc is hard work as a single woman with a spade and pitchfork and I’m lazy, and c) years ago I put in a bunch of asparagus in a big honking row right down the middle!  Also, long-lived blueberries and various perennial flowers and herbs have gotten comfortable and intertwined in rectangle-imposing places…
However, over time the rows have begun to meander of their own accord and different beds have softened at the edges with milkweed and daisies urgently volunteering. So maybe I can just let the edges develop themselves?
Is anyone else growing on an older property with its own stodgy ideas about what goes where?  If so, how hard do you work to rearrange things?

Is anyone else growing on an older property with its own stodgy ideas about what goes where?  If so, how hard do you work to rearrange things?

Yes this farm is over 100 years old. The house burned and we replaced it with a manufactured one.  Grade requirements meant a 10 foot swath had to be bulldozed around the house  Which meant snatching u[ bulbs with each pass.

Previous caretakers had tried to drain wet spots with straight trenches so that they could use a tractor.  They did not work well but maintaining the field with a scythe I discovered that the wet spots connected in a  big Z so I have gradually enhanced that into a swale system that keeps the clay soil hydrated.  

Birds sat on the old fence lines and planted Himalaya blackberries so I just removed the fencing and changed it into an arbore to control them so that now I can sell them for a profit.  This fence was to the west of the row of Logan berries which are susceptible to sun scaled so the blackberries again are a sunscreen like the plum grove mentioned above.

Some ground covers Like the Vinaka major continue to suppress invasion of the blackberries.   I am 81 now so I tend to not change things unless they are a problem that I can't make into a solution.

Here is a clip from the 2017 PDC videos.  Tim Barker talks about "edge" in permaculture design.  It's pretty informative in a short amount of time.  
https://youtu.be/KUM8thGwNeA?si=sxx-wUwVKCau2SSg