Introduction to Naturalised Nursery Practice

Applying the understandings of ecosystem mimicry to create alternative solutions to current nursery practices of disease control, fertilisation and sterile mediums.

It is my belief that nature is our greatest teacher. By observing nature we can see that a tree in a forest is self-maintaining. It does not rely on fertilisation, irrigation, pesticides or fungicides to produce healthy growth. It’s only with today’s technology we are beginning to bear witness and understand nature’s true genius. By applying these newfound understandings of nature’s interconnected network of processes, cycles and flows into our permaculture systems, we can facilitate productive growth in a truly ecologically regenerative way.

Nurseries seem, even to a permaculturist, to be places too sacred and controlled for nature’s chaotic wisdom. The lack of known previous experimentations and available information on alternative nursery practice, coupled with generations of unquestioned current practice, makes the prospect of incorporating these polar opposite ideologies even more daunting.

I was once just such a person, but the knowledge that I gained, studying under Geoff Lawton at the Permaculture Research Institute Zaytuna Farm, Australia, coupled with the observation of nature’s natural cycles, made me question current nursery practices, which I learnt in my previous education and experience in horticulture and nursery management. After failing to find similar nursery systems to the ideas I was theorising, I went about experimenting in a production nursery setting at the Permaculture Research Institute for several months, and independently thereafter.

In this article I will be sharing the understandings that made me question current nursery practices of fertilisation, disease suppression and sterile soil mediums. I’ll be then discussing the implication of these current nursery practices as well as sharing my alternative experiments, observations, results and understandings, followed lastly I’ll be talking you through how to make bacterial and fungal dominated, living (potting mix) mediums.

Be aware that in this case, these understandings of ecosystem mimicry are being applied to a nursery system. But, they are not only limited to a nursery setting. The understandings of ecosystem mimicry can be applied in many other permaculture systems.

How do plants in nature collect the necessary nutrients for healthy plant growth and how does that differ from current fertilisation?

To break down a very complex subject, nutrients are mined or consumed by a diverse array of microorganisms which exist symbiotically within the rhizosphere (the root system of the plant). The plants communicate in their own way with microorganisms and tell them what nutrients and how much they need. The microorganisms then collect and feed the nutrients to the plant, in exchange for sugars exuded by the plants roots.

Current nursery practice short circuits this natural process of nutrient collection with water soluble NPK fertilisation. These water soluble nutrients are taken up by the feeder roots when the plant unwittingly absorbs water. This action force feeds the plants the basic spectrum of nutrients in a large burst. This puts stress on the plant by diluting the sap and degrading cell walls, and by fertilising in this way it neglects other much needed micro and macro nutrients needed for healthy plant growth. All of which creates an unhealthy plant and an opportunity for disease and pests (more on this here).

The problem that arises with water soluble fertilisation is that the plant is no longer naturally regulating its nutrient uptake, as discussed previously. As a result, to prevent nitrification (overdosing on nitrogen), the plant has no choice but to put these overabundant nutrients towards an unnatural flush of leaf stem and flower growth, to the long-term detriment of the plant’s development.

With proper understanding of the natural form and character of a plant’s growth, you can observe the negative implications of this process on the plant. These would include: overlapping leaves and branches, leggy stems without tapering, plants flowering out of season and the plant fruiting well before its natural time. These actions are not part of the plant’s natural character and if exhibited at a juvenile age will have long-term implications in its adult life. The form a plant takes in its juvenile age will be its form that it continues into its adult life. Crossing branches will become rubbing branches, causing an opening for pest and disease and also creating an unnatural canopy structure, resulting in a reduction of potential yield. Leggy stems that weren’t given a chance for proper lignification, due to their unnatural growth, will be without tapering and will have a greater chance of breaking in the outside environment. Two dominant leaders (two dominant trunks) in plants that do not exhibit this form will result in an eventual spilt.

I have observed firsthand with my experiments in a nursery setting that if we work with nature, instead of confronting it, we can facilitate optimal natural conditions for the production of the highest quality of plants. That in turn will provide us with the greatest yields and consistent and increased rates of growth and survival. In my experiments, I observed consistent ideal form, vigour and success rates of plants under experimentation with living mediums that are high in a broad spectrum of available nutrients (not water soluble nutrients) and a diverse spectrum of soil microbiology, compared to that of the controlled test plants grown in a sterile, fertilised medium. It is our greatest stubbornness that we think we know what and how much a plant needs. Plants know what they need and when, to achieve their ideal form, growth and health. Our job should be to help facilitate this natural process by ensuring that a broad spectrum of available nutrients and a diverse spectrum of microorganisms are available.

How does nature suppress disease and what are the implications of current nursery practice for disease suppression?

In nature, symbiotic microorganisms act as a plant’s external immune system, fighting against parasitic microorganisms (soil born disease). Studies have shown that a plant under attack from soil born diseases will devote up to a fifth of their acquired energy into feeding beneficial microorganisms. They act as the army defending their host against the invasion of parasitic microorganisms.

To truly understand the parasitic microorganisms that we call disease, we must understand their role in nature. Microorganisms that cause disease are nature’s method of maintaining the balance of diversity and strength of species within ecosystems (more on this see video here and post here). Parasitic microorganism’s ‘diseases’ are unlikely to succeed in attacking a nutrient-rich, healthy plant, which is host to a diversity of beneficial micro-organisms. Disease occurs in nature when a single species of plant becomes too numerous in a single area or ecosystem — because they require the same nutrients from the same microorganisms they begin to compete with themselves for the eventual limited supply of those nutrients. The net result of this struggle is a nutrient-deficient, unhealthy plant that is susceptible to damage by disease. Once the plant succumbs to disease, the floodgates are open. Disease spreads to adjacent plants of the same species, which are also deficient in nutrients due to competition. This trend continues until only the genetically superior or isolated nutrient-rich plants are left, thus returning the ecosystem back to its natural balance of diversity.

Within a healthy ecosystem, one rich in diversity and flush with microorganisms and nutrient dense healthy plants, disease outbreak is unlikely.

Therefore we should rethink our perception of plant disease. Our current mindset sees it as a war to be conquered with fungicides and the like, which is merely treating the symptoms and causing greater damage without addressing the real problems. Only after understanding the problem in its truest form can we go beyond to the solution.

Current nursery practice uses a sterile soil medium, devoid of soil microbiology, with the goal of preventing contamination by parasitic soil organisms — it’s an attempt to maintain a controlled environment that limits the loss of plant stock. In my research and the experiments that followed, this understanding became counterintuitive. A sterile soil medium creates a void and an ideal environment to which parasitic organisms are attracted and where they subsequently find no limitation for their spreading. It is an extremely delicate system that requires vast amounts of fungicide and a sterile nursery practice to keep in check.

In my experiments I observed a higher success rate of germination of tree species, germinated in a living soil medium, than that of the controlled stratified/scarified seed subjects. It’s my belief that fungi hyphae have a necessary role in scarifying the seed husk, and in activation of the germinating embryo, than we currently understand. In all cases the success rate of germination and survival was far greater than the controlled subjects. It is my understanding that the symbiotic relationship with microorganisms formed during and post germination of the living medium trees came at its most important time in the trees’ growth. The protection of disease and nutrient uptake is most needed in that critical juvenile growth period, both of which are not accessible in the sterile controlled subjects.

The living medium subjects that went through this germination process were always almost identical in ideal form and vigour. That being said, when the results of the experiment were not perfect, the low percentage that was lost to disease exhibited the interesting characteristic of the disease not spreading. As they were from the same batch of prepared living soil medium, it would suggest a possible genetic weakness inherent in the plant itself.

There is a current practice of inoculation of single strands of scientifically studied beneficial microorganisms into a sterile medium to assist with plant growth. It is my opinion that although this is a step in the right direction, it still exhibits the same mindset — that we think we know what’s best for the plant. We have come a long way and yet we have only scratched the surface in understanding the diverse interplay and roles of different microorganisms and their relationships with plants. If we supply the maximum diversity of different micro-organisms, the plants have the capacity to find the symbiotic relationships with the microorganisms they wish to form them with. The other organisms that we might not completely understand might have other significant roles in maintaining a healthy ecosystem within the soil. It has been my observation that this understanding only works with healthy plants, with a medium that creates healthy habitat for microorganisms. An analogy would be that you wouldn’t form a partnership with a business which is failing. Why would microorganisms form partnerships with unhealthy plants unable to supply the necessary sugar exchange?

Another observation is that the plants that were part of the living medium experimentation had a greater success rate post transplanting. One of the reasons for this success was the inoculation of beneficial soil organisms within the transplanted pot, and which would spread to the surrounding soil post transplanting. This inoculation spread micro-organisms which would later work to form ideal humus rich topsoil and a diverse ecosystem of soil micro-biology, ensuring the healthy future growth of the plant.

How are living mediums different from your traditional potting mix and how do you make it?

The recipes should be easily understood and created by anyone with the basic hands-on experience of permaculture gardening or nursery work, and for those with horticulture or nursery backgrounds. I’ll talk to you now on how the mixes are similar to that of your traditional potting mix, in that the initial goals are the same — to create a medium that retains moisture, but drains well, and keeps air porosity high and facilitates the slow release of nutrients. However the difference you should take into account is that you are not only creating an ideal habitat for plant growth but an ideal environment for microorganisms and natural sequences to flourish.

Fungi dominant compost and vermicompost act as a substitute for vermiculite. The water stable aggregates within living composts, in my experience, have a far greater water retention capacity than that of vermiculite. The combination of course river sand and compost particles creates a soil matrix which forms a balance of water retention and drainage. The addition of biochar and course river sand creates the needed air porosity, and in my experience, biochar, for this medium, is a far superior substitute for the non-renewable perlite. As well as maintaining air porosity it creates a massive surface area which acts as a habitat for microorganism as well a plethora of other benefits. The paramagnetic gravel or rock dust (preferably granite) acts as thermal mass heat retention to create a levelled temperature within the medium. This also creates microclimate and habitat for microorganisms, as well as a number of other complex functions and nutrients.

Though observation and experimentation I have found the living medium was not subject to sour soils. The medium improved over months rather than degraded, the microorganisms balanced the pH and broke down the remaining organic matter within the medium, creating humus. The ideal environment within the living medium attracted beneficial insects and worms which in unison with the microorganisms prevented the collapse of the oxygen exchange rate and compaction by creating micropores within the pot. To my great excitement the living medium attracted other needed elements to create a living ecosystem within the pot. Life attracted life.

To simplify, there are two basic recipes, one is for trees and perennials that prefer a fungi dominate medium, and a medium for annuals that prefer bacteria dominance. These recipes can be tweaked to suit the plant and the conditions of their surrounding environment.

The bacteria-dominated medium consists of 28-day hot compost with a broad spectrum of available nutrients. This is then sieved through a 1cm2 wire mesh, to eliminate any larger material. This material is then placed through a vermiculture (worm) compost to create vermicompost. Once the vermicompost is ready, mix 8 parts of it with 8 parts of coir peat (coconut fibre pith), with 2 parts course river sand, 1 part finely crushed paramagnetic gravel or rock dust and 2 parts finely crushed biochar. These ratios and ingredients are not dogmas. I find when people get too caught up with the ratios problems arise. It’s all about the feel. I suggest you experiment with a small bucket first and use the ratios as a guide. The feel you should be aiming for is a perfect loam — add water, see how it reacts, then adjust accordingly. Write down your revised ratios and calculate for the amount you wish to create.

The fungi-dominated recipe consists of a 90-day hot compost, with a broad spectrum of available nutrients and a maximum diversity of micro-organisms. I will state that not all composts are created equal, and high quality compost with a maximum broad spectrum of micro-organisms and available nutrients is needed for the success of this system. The compost is then sieved and separated into two different grades, 1cm2 or less and larger material. The larger material is very important as it acts as the slow release of nutrients that feed and house the microorganisms, that in turn feed and protect the plant for the months following.

Add 9 parts of the larger composted material followed by 3 parts course river sand, 1 part biochar, 6 parts finely sieved compost, 1 part paramagnetic gravel or rock dust — in that order. The medium should be mixed thoroughly between adding ingredients.

The same previously mentioned rule about developing a ‘feel’ for the correct recipe is needed for the fungi medium also, as the compost may vary greatly depending on the compost structure. Always make a test batch in a bucket or large container first and use the ratios as a guide. The feel you are aiming for is forest humus. It should be spongy but should crumble into peds (breadcrumb-sized particles) once compressed and moved through the fingers. Adjust ratios accordingly, then write down your result, calculate and apply on a larger batch.

As this is a living medium I suggest you prepare it just before use, or if there is leftover medium treat it as you would a compost pile — water it, avoid waterlogging and keep it out of direct sun.

In my next article I will be discussing how to create ecosystems within a nursery, and how with the use of companion planting and the introduction of beneficial insects and animals you can control pest and weeds.