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Permaculture Research: The Reality of Food Forests

A newly established swale food forest at PRI Australia,
backdropped by an 8 year old food forest. Photo: Fraser Bliss

We have heard about the wonders of permaculture food forests, whereby nature does all the work and we can simply walk around harvesting more food than we can possibly eat. Bill Mollison, the founder of the permaculture movement, is known for saying that the world is "in grave danger of falling food". This is an incredibly appealing idea that certainly has its roots deeply embedded in the human psyche that craves for a paradise lost, a Garden of Eden and the freedom from the toils of work. But is this achievable? What data supports these claims?

These questions I had in mind when I went to the Permaculture Research Institute of Australia to take Geoff Lawton’s Permaculture Design Certificate (PDC) course and 10-week internship program. At his farm, I walked through food forests that had been established a decade ago and observed their diversity and stability with my own eyes. It was apparent that these forests of food didn’t plant themselves. They were a direct result of thoughtful design and obviously someone had planted them and guided their growth over the years.

The challenge working with natural systems is that there is never one single variable that affects outcomes. In nature, there are more factors that we can identify and measure. This holds especially true when one works together with nature, not against it with force. That is why I took it upon myself, together with fellow intern Theron Beaudreau, to conduct research and measure the amount of work required to maintain and establish food forests.

We performed chop and drop maintenance on food forests of all ages and sizes from those newly planted six months ago to very stable nine year old systems. We also designed and established a new food forest measuring 550 m2, containing a great diversity of sub-tropical trees and plants.

All labour was recorded over a three month period of time. Everything was done manually with hand tools and no fossil fuels were used (except a short visit by car to a local tree nursery).


  • All food forests were located on or below swales.
  • Research occurred during spring-summer in the subtropics of northern New South Wales in 2011.
  • The experiment was for educational and research purposes. The amount of labour input could be potentially reduced and thus results are on the conservative side.
  • Some food forests had been relatively well maintained and others had hardly or never been touched since they were planted.
  • The food forests were located on different zones and parts of the property, and some had their own unique variations of microclimate.

From the analysis of the research data several conclusions can be drawn:

As a food forest ages and stabilizes, the maintenance required to maximize productive output (mostly chop and drop) decreases up to 93% over 10 years. Another way to look at this is one can cover up to 14 times more area per hour of work on food forests that are a decade old and well maintained. If this pattern is extrapolated, it can be assumed that food forests, like normal forests, will eventually reach a stage when little to no maintenance is required.

If chop and drop maintenance of a food forest is not regularly performed, this leads to a four-fold increase in the amount of future work to clean it up and optimize the productive output of food. It is therefore recommended to do a small amount of maintenance preemptively to avoid unnecessary work later and to keep growing conditional optimized. The research data aligns with the general recommendation that food forests should be chopped and dropped ideally every six months (in the subtropics, less in cooler climates).

In the first three years of a food forest’s life, the maintenance effort drops 70% and then plateaus for at least five years if not adequately maintained. Thus without regular maintenance, one is not getting maximum benefit from their food forests.

It is only slightly more effort to plant and establish a new food forest than to try to recover a young one (six months old) that has been overgrown due to a lack of maintenance and perennial cover cropping. That reinforces conclusions drawn above that it is a better use of one’s time to properly maintain existing food forests and have time to plant new ones, rather than spend all one’s time trying to recover forgotten ones. This also illustrates that an essential part of food forest establishment is to fill in the niches between trees with plant species beneficial to the system and your desired outcome. For example a sweet potato cover crop that blocks the overgrowth of grasses and weeds.

The results of this research speak for themselves, however in order to fully answer my original question of the achievability of permaculture food forests that require no work, more time and research is obviously required. It was beyond the scope of my project to measure and evaluate the productive output of food relative to labour inputs. However, my personal observations were that well maintained food forests did seem more productive than those that weren’t, which makes sense, but doesn’t exactly qualify as research data.

Does that mean that the claims of permaculturists are exaggerated? Well, it depends how you look at it. The data does suggest that stable food forest systems at their successive climax no longer require the input of humans to produce decent amounts of food. But of course, one cannot get away without strategic design, planning and a few hours at the end of a good pair of loppers in a regular session of chop and drop to tweak the system to your advantage. Yes, nature does the vast majority of the heavy lifting, but you still have to walk around and harvest it. Food won’t magically fall out of the sky into your mouth.


Fraser Bliss is a permaculture consultant, designer and teacher with a background in international business systems consulting.


  1. Great article Fraser, it is nice to see the newly planted food forest and I appreciate your research and data. Please share more info as it comes through. Blessings.

  2. Thanks Fraser, to really get an understanding of the benefits of such a food forest I would think the article lacks a crucial set of data -: the amount of generated edible food for humans and perhaps fuel as well. Because if the proverbial hits the fan, I’d expect these systems survival would depend on people valuing the trees more for their food output vs their fuel value….

    Also with the money- and jobs supply contracting every dollar spent has to be spent wisely. Investing in earthworks and seedlings is not cheap so we need to be sure we’re getting food from the systems in the future.

  3. Well done Fraser. After working on the new food forest with you it is cool to see how you have taken that experience and turned it into some good data analysis. Thanks for posting and hope you guys are doing well.

  4. Great to see more work being done with food forests! As a food forest advocate myself, specialising in urban food forests, I’m surprised by the degree of scepticism amongst Permaculture people in regards to the viability of food forests. As you say, the results speak for themselves, and when people see the results of a competently and well designed food forest with their own eyes, opinions quickly change.

    I’m impressed how you’ve researched the maintenance labour requirements and have shown that the labour decreases quite significantly over time. Coupled with the fact that fruit trees take at least 5 years to establish properly and start producing decent yields, this would suggest that after ten years, the food forest will reach a point where it is potentially reaches levels of peak production and minimum maintenance.

    Great work!

  5. Thanks all for your comments.

    It was a fascinating 3 month experiment and I am happy that others can also benefit from the work that went into it and the data that came out of it.

    As with all permaculture projects, one must evaluate available resources and their potential uses against environmental factors to determine the best potential outcome. That usually means keeping things as simple as possible and focusing on a carefully chosen set variables to work with for the data to be meaningful. The results of this experiment do speak for themselves, but of course we mustn’t forget that those results will be different in a different climate, a different season, a different year or by a different researcher. We need more research, and we need to connect the dots between different studies. So I encourage everyone to observe, record and share as much data as you can, even if that means simply tracking the hours you spend in a garden, measuring the produce coming out of it, or recording the temperature of your compost heap in an spreadsheet.

    For a system even approach a stage of permanence, we’ll at least have to know our time is not better spent doing something else.

  6. Thanks for doing research like this. I think that the PRI should appoint someone to do research like this on all their food forests in different countries.

    Of course “all” work cannot be eliminated, you have to harvest, store, cook, chew, digest, use the manure etc. But the actual ‘maintenance’ of the food forest requires only chop and drop, and this is a great thing.

    The next thing to do is to measure the amount of ‘energy’ required to produce certain amount of things out of a food forest compared to the energy required by conventional agriculture in different places. Probably I will be doing this research a few years from now.

    I didn’t understand the work hours measurements clearly. If you can explain those it will be very helpful.

  7. The numbers in the columns that are in black are the number of man hours for each specific job.

    Since the food forests were not all of the same size, the numbers in blue indicate how many square metres per hour one can cover for each type of work: chop and drop, cover cropping, planting, etc.

    This enables one to make a comparison of the labour requirements of different food forests at different stages of development. For example one person can only chop and drop 15.4 m2 of young food forest per hour but 120 m2 per hour in well established older forests because they are more stable and there is less work to do.

  8. This was very interesting and a very concert practical example of Permaculture information. I was wondering though over what period of time did each forest receive its maintenance work. In the example of the mature food forest, over what period of time did the food forest receive 10 man hours of chop and drop time? 10 man hours a year? a month?

  9. I somehow missed this article when it first came out. Thanks for taking the time to put the research together in this very easy to digest form, Fraser! It was great working with you and I hope that our paths will meet again at some point (Nepal perhaps?)

    One other observation I can contribute to this piece is, in the establishment of a new food forest, the point of diminishing return. There is a point in just about any system where the returns on energy invested begins to substantially diminish. As a result, you find that there is still a significant amount of work that COULD be done… but the amount of energy you invest may not be worth the diminishing results.

    Establishing a successional (annual to perennial) ground cover in a food forest is a great example. A ground cover plays a critical role in the reduction of maintenance of a food forest over time. However, if you spend MORE time establishing a ground cover system than you would maintaining a system that lacked an adequate ground cover you might consider yourself past the point of diminishing returns. At this point, its a good idea to take a step back and consider how your time and energy can be more effective and efficient.

    If your goal with a food forest is a passive, low maintenance food production system it’s important to recognize when you’ve hit or passed these milestones and avoid the artist’s tendency to continue investing energy into a finished piece. And don’t worry, there will always be plenty of work to be done elsewhere!

  10. Very interesting article, thanks!

    In my 7 year experience of trying to create a food forest, I have become aware that one of the most critical limiting factors is my knowledge, or rather, lack thereof.

    It may be that designing, planting and maintaining a food forest is child’s play when you know how. The problem is that this knowledge is not that easy to come by.

    I’m in an area (Northern Spain) where there are no long-term established permaculture sites, at least none that are near to us. Having done a weekend course with Martin Crawford at ART in Devon and watched Geoff Lawton’s Food Forests DVD, I have been pretty much feeling my way in terms of planting and running the food forest.

    My strategy, based on an awareness of my own ignorance, has been to try lots of different species (whatever I can get my hands on for cheap or free, mainly) and over time see how they function, and then keep the ones that do best.

    No doubt there are other limiting factors (such as my time and energy, the fertility of the existing soil, and the suppressing effect of grass on tree growth — this land is former pasture.)

    The upshot is that after 7 years (in a temperate maritime climate — not subtropical) our food forest is still very much in the establishment phase. We do get some yield from it, but intermittently, and not enough to make it a major part of our food budget.

    The knock-on effect of this intermittent yield is that it is easier for us to get into the habit of going shopping for food rather than looking for it in the garden!

    Are there a lot of would-be food foresters out there in a similar position to mine? What can we do about it?

    In our case we would be delighted, for example, to offer free food and accommodation to a student who would like to come and gain experience managing our food forest in preparation for planting their own some day (and learn Spanish while they are at it).

    Any takers out there?

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