6 Basic principles of garden building and management
This is not a chapter about how to build sheet-mulched garden beds. While it does have some hints about garden building techniques, the chapter focuses on design principles such as integrated pest management, stacking and guilds, as well as discussing the importance of soil.
We have already discussed how a permaculture design is a combination of techniques and strategies - how we build the gardens and why we place them there. Keeping this in mind, we should now realise that the garden areas should be:
• mainly perennial - mostly herbs and some vegetables, such as eggplant and globe artichoke, which last several years.
• self-perpetuating - allowing nature to take its own course by letting some vegetables self-seed each year. This may not be possible in very small gardens.
• diversified - place in the system as many different plants and animals as possible. Diversity is the key to successful gardening and forage systems.
The garden beds we build are organic ones. This means that we don’t advocate or use chemical sprays for pests, we use compost and mulch as natural fertilisers for our growing plants, and we practise sound garden management and husbandry to minimise disease.
Organic and biodynamic farming systems have been shown to be viable, although they may not exceed or match the yields of traditional chemical farming methods. Organic produce usually gives a higher return for the crop, and with lower input costs, these food production techniques are seen as appropriate gardening and farming strategies. Organic and biodynamic food may not be produced in large quantities, but the quality is far better and more nourishing than chemically produced food. The secret to healthy food is healthy soil.
A plant’s ability to ward off disease is strongly dependent on the health of the soil. Soil is alive! Healthy soil contains a good balance of nutrients and elements, living organisms, humus (decaying matter), water, air and soil particles. This allows plants to obtain the necessary substances they need for growth, repair and disease immunity.
The mining of minerals from the soil by plants and the subsequent replacement and cycling of these minerals, with the creation of productive healthy soil, is one of the key design strategies in permaculture. The soil is the key to successfully growing food crops.
Soil is a combination of different particle sizes. It is a mixture of sand, silt and clay, the differences of which are shown in the following table.
The best soil for gardens is loam which contains about 20% clay, 40% silt and 40% sand. Loam also contains organic matter. This is essential for sustainable fertility, as it improves the structure, field capacity, exchange capacity and many other features of the soil.
Table 6.1 The classification of soil particles.
| Particle | Size (mm) |
| clay | < 0.002 |
| silt | > 0.002 < 0.02 |
| sand | > 0.02 < 2.0 |
Figure 6.1 The composition of different soil types.
Clay soil is usually heavy, becomes waterlogged easily, and any holes dug for plants create wells full of water which eventually kills most trees. Clay is important in holding and then releasing water and nutrients to plants, but too much can create poor soil structure, depending on the chemical nature of the clay. For example, if the clay forms an impermeable barrier, it waterlogs easily. However, if the clay forms a crumbly structure the soil may be rich in nutrients.
It might be all right to say that you can easily change soil, but if you have lots of clay the expense of adding gypsum or sand or breaking the clay up can be prohibitive, depending on the local availability of gypsum or the area that needs treatment. Small areas where the house vegetable gardens are can be treated, but large areas would be impractical.
Clay has a high cation exchange capacity. Ions loosely held by the clay particles are exchanged with others from the surrounding soil and plant material. The exchange capacity of the clay depends on factors such as the soil pH, the types of ions held by the clay and the amount of organic matter present. For example, in highly acidic conditions (low pH) iron and aluminium ions are released by the clay, resulting in potentially toxic levels of these elements for plants in the soil. Figure 6.2 shows how zinc and calcium ions, for example, are exchanged with hydrogen ions from the plant roots.
Figure 6.2 Clay binds positive ions (cations) strongly to its surfaces. These cations can be progressively released to plants by exchange with hydrogen ions.
Sand doesn’t have these cation exchange properties anywhere near the same extent. It can be gutless, with low water-holding capacity and high leaching.
Sand has good drainage. The larger particles, and large pores between these particles, allow water and air to move through it easily.
Silt has a balance of the properties of sand and clay, with reasonable water-holding and water-releasing ability.
The other major component of soil is organic matter. Land owners often have to work to increase the organic matter content in the soil. Once the soil becomes “alive” again with the proliferation of organic matter and organisms, such as bacteria, fungi and earthworms, then nutrients become available to plants, plants are healthier and resist disease, and crop production increases.
Furthermore, more water can be stored in the soil. Even sandy soils store about 0.8 mm of water in 1 cm of soil.
However, soils with high organic matter can store 3.5 mm of water for every centimetre of soil, so there is a very good case for building up our soils with humus and organic matter.
Mulching is one way to improve soil fertility which mimics natural forest systems. Organic mulches of chipped plant material, for example, can be spread about 5 cm thick over the garden beds. The mulch slowly breaks down and the action of micro-organisms and macro-invertebrates, such as earthworms, releases nutrients to the soil.
Mulch protects the soil, keeps the soil cool, allows greater water infiltration and reduces water loss by evaporation. Mulch also prevents erosion during thunderstorms with torrential rain, and the lower temperatures under the mulch keep microbes and earthworms happy. The soil should always be covered, and areas for growing living mulches, such as mustard and clover, should be considered.
Mulches can be made of both living and non-living material (organic and inorganic, respectively). Rocks and plastic can be used to cover the ground, but mulches of organic matter, including newspaper and cardboard, and shredded plant material, are much better in most cases. Organic mulches are best as they will, in turn, break down and provide greater levels of nutrients for plants. (Using rocks as a mulch is a design strategy in desert regions.)
The most important contribution of organic mulches is the lignin and other substances that they contain which are transformed into humic acid. It is the continuous production of humic acid that has sustained the fertility of rain forests for thousands of years due to its powerful chelating properties. That is, nutrients are held within the humic acid structure and thus are made more readily available to plants.
Figure 6.3 Weed-free, deep litter leaf fall from Acacia saligna. Mulches reduce weed growth.
A large range of mulches is usually available. Each has its own particular use and you should use the mulch best suited for the job. For example, if you want to get rid of a lot of invasive weeds, then black plastic or some other lightproof membrane is ideal, while to cover an established garden bed, full of herbs and vegetables, then only a plant-based mulch, such as shredded tree primings, should be used.
Wherever the ground is permanent sod or mulched the soil structure improves. However, where the surface is tilled or left bare by using herbicides, soil structure becomes unstable, with low porosity and higher risks of erosion and degradation.
Figure 6.4 Water dropping onto bare ground causes soil to be lost by erosion. Mulch protects the soil and minimises topsoil loss.
Mulch is great for almost every situation. However, a mulch layer on the garden beds in frost-prone areas during the colder months is not appropriate, as we have discussed in Chapter 3. Mulch prevents heat loss from the soil but frost tends to settle on the mulch and plants in the garden. Bare ground is a better alternative for these times because heat can radiate from the soil surface at night, minimising frost damage.
Soil conditioning and treatments
Permaculture is about restoring and rejuvenating the land, not mining it. Even though permaculture concerns itself with holistic, integrated design, it is not important to include every known strategy for improving the soil in the design, nor could every idea be put into practice.
However, sometimes soil needs to be changed. You may often notice that particular weeds are flourishing where you don’t want them to be, or your plants look yellow and weak.
These weeds and many other plants can be used as indicators of soil health. Their presence suggests that the soil could be acid, wet, clay-based, sandy, nutrient deficient or some other condition. For example: in Western Australia, sorrel (Rumex spp.) and soursob (Oxalis spp.) suggest acidic soil; blady grass (Imperata cylindrica) or barley grass (Hordeum leporinum) suggest salt contaminated soil; while castor oil plants indicate recently cleared land and bracken fern a recently burnt area. The following table summarises some of the plants used as soil indicators.
Once an assessment of the soil has been made you can then decide how the soil needs to be conditioned or treated. Soil conditioning is the gentle changes you make to the composition, nature and structure of the soil. Frequently, it involves loosening the soil and/or adding amendments to change acidity, alkalinity or chemical composition. A full soil analysis of the types of minerals present is the only means of accurate soil nutrient amelioration and balance.
Table 6.2 Plants as soil indicators.
| Plant | Soil indication |
| Clover (Trifolium spp.) | low N |
| Salad burnet (Poterium sanguisorba) | alkaline soil |
| Fat hen (Atriplex hastata) | high fertility |
| 1 Stinging nettle (Urtica urens) | cultivated soil, high fertility |
| Sheep sorrel (Rumex acetosella) | sand, acid soil, low in magnesium |
| Plantain (Plantago spp.) | cultivated, wet, clay soil |
| Wild radish (Rapranus raphanistrum) | low fertility |
| Dock (Rumex spp.) | wet, acid soil, low in magnesium |
| Horsetail (Equisetum spp.) | wet, clay, acid soil |
| Bracken fern (Pteridium aquifolium) | low K and P, acid soil |
| Chicory (Cichorium intybus) | cultivated soil, clay |
| Barley grass (Hordeum leporinum) | salty soil, water table near surface |
Soil conditioning can occur by several methods. For small urban properties, a garden fork pushed into the soil and moved slightly to and fro will cause air and water to freely enter the soil. Alternatively, deep-rooted plants, such as daikon radish, comfrey and dandelion, or larger tree species, such as Acacia spp., will have the same effect, but slower.
Finally, let earthworms do the job for you. Place a layer of compost or mulch on the soil surface and let the earthworms do the rest. Earthworms are nature’s gardeners.
In some countries, such as those in the UK, Europe and America, large animals such as moles and gophers, and insect larvae, supplement earthworm activity by their burrowing habits. In the drier areas of Australia (and in some other countries) where earthworms are seldom found, ants replace earthworms in the ecosystem. Ants fill an important niche in the cycling of matter.
For small acreage and broad scale farms, mechanical aeration with chisel ploughs (for example, Wallace plough and Yeoman’s plough), or even a stump jump scarifier, can be used. These slice through the soil, cutting deeper each season, breaking up the compacted soil without turning it over like a conventional disc plough.
Figure 6.5 For suburban backyards, a garden fork or deep-rooted plants help improve aeration and drainage.
Mechanical machinery should not be used on steep slopes. Instead, the use of deep-rooted trees, such as pine and oak, will improve soil structure. These types of trees create soil while others, such as eucalypts, deplete the soil of its nutrients. Ploughing should be done along the contours as part of the keyline system of land management, which is discussed in more detail in Chapter 9. If you wanted to plant a tree shelterbelt you would make only one run at the deeper cut (50 cm or more). Chisel ploughs can be used, but it is more common to “rip” the ground to a depth of about one metre using a bulldozer, pulling one to three rip tynes. This single, deep cut allows seedlings to become better established by sending down roots more easily in search of water.
Figure 6.6 Chisel ploughs are used, with increasing depth of cut over a couple of seasons, on both small and large farms. This improves aeration and drainage, breaks up compacted soil and permits plant roots to penetrate deeper into the soil.
As much as possible, minimum tillage should be practised. Heavy machinery and large numbers of stock easily compact some types of soils and this needs to be examined. Unfortunately, minimum tillage often implies the use of herbicides. By planting clovers and other leguminous plants, and using crop and soil management strategies, herbicides are not needed.
Many farmers (and gardeners) plant green manure crops which are easy to grow in most local conditions and which produce large amounts of plant biomass. These plants can be turned into the soil to improve its quality, and increase nitrogen and other nutrient levels. Other types of plants, called cover or catch crops, trap nutrient run-off and protect the soil. These plants can be harvested, by slashing for example, and used as a source of mulch and for compost making. Table 6.3 lists a few examples of green manure and cover crops which can be grown in particular seasons.
Finally, there are soil additives that you can use to ameliorate the soil. You might want to change acidic soil to become neutral, improve drainage and water and root penetration in clay, or provide particular natural fertilisers to improve soil fertility.
Table 6.3 Green manure and cover crops.
| Season | Plants |
| Summer | cow pea*, lablab *, Japanese millet, sorghum, vetch * |
| Autumn | lupins*, canola, faba beans*, oats, field peas*, barley |
| Winter | oats, canola, mustard, faba beans *, barley, field peas*, rye-corn, sub-clovers*, medics* |
| Spring | cow pea*, vetch*, canola, sorghum, pinto’s peanut*, mustard, buckwheat, lupins* |
* legumes. All other green manure crops listed in the table are non-legumes.
For example, areas near coastal regions often have sands which are typically leached and low in nutrient content. Sometimes, these sands lie over limestone and are thus alkaline (high pH). Some amelioration, by adding acidifying substances such as sulphur and slow-release fertilisers to improve the nitrogen and phosphorus content, needs consideration before planting is undertaken. Some of the more common soil treatments are shown in Table 6.4. Many others, such as magnesite and rock phosphate, are not discussed.
So important is the soil to our very well-being, that I believe when the structure of our soils collapse because of over-stocking, chemical damage, over-burning, erosion and nutrient exhaustion, so will the human society, which over-works the soil, collapse.
Your garden should be a place of harmony between all of the elements in the system. Why is it that many gardens are riddled with pests and everything else has a feed of the vegetables you planted? You never get to pick fresh fruit and vegetables, so you just give up. Sound familiar? Maybe it is time to try integrated pest management.
Integrated pest management is a holistic approach to pest control. It is used in conjunction with the five principles for a healthy garden. These are:
1. Develop a sustainable polyculture.
The concept of sustainable polycultures was discussed in Chapters one and two. Basically, we want to grow a range of different plants that have different functions (niches) in the garden. For example, scented herbs and attractive flowers can be used as borders of garden paths. You could consider beds which have a seasonal theme such that different beds flower in spring or summer, or arrange plants such that there are always some in each bed which are flowering all-year-round. These herbs and plants may also repel pests and some will have medicinal, culinary or other uses. Flowers are also important for adult ichneumon wasps and hover flies which must have nectar before parasitising pests with their larvae. The orchard area is another place where polycultures can be developed. For example, you could underplant orchard species with:
a. companion plants for pest control - such as nasturtiums, tansy and rue. Plants should complement others nearby.
b. ground cover to smother weeds and utilise the area - such as sweet potato, melons and pumpkin.
c. green manure crops to slash or turn in - such as clover and mustard.
Table 6.4 Soil amendments.
| Substance | Uses |
| Gypsum | improves drainage in clay and supplies essential protein-building “sulphate” |
| Dolomite | changes acid soil to alkaline, contains calcium and magnesium |
| Limestone | changes acid soil to alkaline, contains calcium |
| Rock dust | ground rock for sources of most nutrient elements |
| Blood and bone | organic fertiliser, high nitrogen and phosphorus content |
| Seaweed (kelps, not sea grass) | good source of trace elements, all-round fertiliser, high potassium |
| Worm casts | excellent, balanced fertiliser |
| Sulphur | changes basic (alkaline) soil to acid |
| Wood ash | from fires, contains high potassium levels (caution: very alkaline when fresh) |
| Lime | changes acid soil to alkaline, contains calcium |
| Sheep and pig manures | high levels of nitrogen, phosphorus and potassium |
| Cow and horse manures | slow release fertilisers, lower nitrogen content |
| Poultry and pigeon manures | very high nitrogen content. Pigeon manure contains the highest broad spectrum of all trace elements |
| Bentonite | expansive clay to increase water holding capacity of soil and cation exchange capacity of light sandy soils |
There are many other ways in which complex ecosystems and polycultures could be set up. Why not experiment!
2. Use a diversity of strategies.
Some pests find food by the chemicals produced by the host plant. If you plant lots of the same type of vegetables together (as a monoculture) then the chemical signal is much stronger. This means you attract more pests.
Getting rid of garden pests naturally is difficult. You must use a range of strategies or you will be doomed to failure. The next few pages illustrate some ideas.
Organic growers use crop rotation as a strategy against pests and disease. The rotation of annual crops limits pest and disease attack and reduces over-exploitation of particular nutrients which would be mined year after year from the same soil. Many pests have part of their life cycle in the soil. By changing the location of particular plants each year you can disrupt this cycle. For example, in the same patch of ground you might plant carrots in the first year, then tomatoes in the second year, then silverbeet in year three, potatoes in year four and so on.
Figure 6.7 Sawdust barriers discourage snails and slugs.
3. You don’t have too many pests - you haven’t got enough predators!
Aphids might be a problem for lemons or roses but they are seen as an opportunity by ladybirds. This philosophy ensures that we see the solution, not the problem. We look at problems differently and, in this way, decide that we don’t have a snail problem, but we do have a duck deficiency.
Figure 6.8 Grease on the base of trees discourages climbing insects. It is best to place the vaseline on a band rather than directly on the bark.
Permaculturists design for predators. We develop strategies to attract predators to the garden and let nature control the pests.
4. Don’t allow any … icides near your garden.
Pesticides, insecticides, fungicides and weedicides kill useful predators as well as the pests. Avoid them! There are lots of alternatives.
For example, if mildew is a problem look for the cause. Consider shifting the plant into a breezeway or don’t use sprays or sprinklers for watering. If you have to treat a plant for mildew use a “tea” of some combination of chamomile, stinging nettle, comfrey or horsetail. All of these contain silica which inhibits the growth of fungus.
Figure 6.9 Crop rotation breaks the life cycle of some garden pests.
5. Nurture the soil.
Get the plant Nutrition right and you eliminate most disease problems. It really is as simple as that. Healthy plants living in healthy soil do not get diseased easily and can ward off disease. There is much we do not know about how plants resist disease organisms, but we do know that they can, given the correct minerals and nutrients they require.
Figure 6.10 Use natural predators to eliminate pests.
Figure 6.11 Umbelliferous plants attract predators to the garden.
Figure 6.12 A pond also helps in pest control.
Figure 6.13 Adequate pest control requires a range of different strategies.
Figure 6.14 Make pest traps in the garden. This is much better than spraying pesticides.
Too often we forget that in the living world, and in our own garden, we are the most serious pests. We compete for food with a whole host of other animals, and we must become smarter about how we can obtain and satisfy our needs and look after the other creatures at the same time.
Figure 6.15 Companion planting ensures a healthy garden.
Many native peoples throughout the world practice sustainable forage systems. Vines, shrubs, herbs and trees are all grown together in a technique commonly known as stacking.
Figure 6.16 Practice sound management techniques in the garden.
Stacking also occurs in nature. In any natural forest, you will find plants stacked together - tall trees have understorey shrubs and small trees, and grasses and herbs occupy the ground level. Below the ground, root and tuber plants proliferate.
Stacking allows as much as possible to grow in the smallest possible area. Dense plantings such as these suppress weed growth and soil erosion, and ensure that all ecological niches are filled by plants you need for your garden.
The degree to which stacking occurs depends on limiting factors such as the amount of water, light and nutrients. You would expect, for example, to find a denser grouping of plants in a well-watered garden than in a natural, dryland climate area.
Stacking uses vertical growing space more effectively. You should arrange or stagger plants according to height, tolerance to shade and so on.
For example, grape vines can be grown over a fig tree. Pumpkins and melons can be grown up and over a shed wall and roof - all utilising the free space available in a system. You can use trellis, fence, tree trunks and walls to obtain more vertical growing areas.
Figure 6.17 The principle of stacking.
Using the principle of stacking allows other possibilities. For example, you should aim to have successive crops of edible foods throughout the year - a variety of fruit trees such that you are always picking some fruit any time, any season. Furthermore, you don’t have to wait to plant the next season’s vegetables until you’ve cleared and finished picking that season’s crop.
Time stacking is a technique where new seedlings are planted or come up as the previous crop is finishing.
There is less waiting time between one picking time and another. For example, you can grow silverbeet, onions and globe artichokes together. The silverbeet grows the fastest and is harvested within eight weeks. The artichokes take about four months to grow and flower, and finally the onions plod along and can be harvested after six months.
After the silverbeet is harvested, you can replant new seedlings and so the process continues. I will add that silverbeet can be harvested over a long time if you only pick one or two leaves from each plant at any one time. New leaves will regrow and so harvesting continues for quite some time.
Figure 6.18 An example of stacking in a temperate-Mediterranean climate.
Designing leads to the selective placement of objects, both living and non-living, in the system. The placement of living elements occurs as we try to maximise the benefits to each species. In this way, guilds are formed. A human-made guild is modelled on the functional, symbiotic diversity we so often see in nature.
Guilds are thought of as harmonious assemblies of several species around a central element (either a plant or animal). For example, for an orange tree, herbs such as lavender and rue would be planted as understorey to repel pests, and nasturtiums as ground cover (also repels insects) and to smother weeds and grasses. Clover and vetch can provide nitrogen in the soil, and an albizia tree is also planted nearby to attract ladybirds to eat aphids.
Figure 6.19 An example of an orchard guild.
Ducks or chickens can be occasionally let in to eat slugs, snails and insect pests. (Poultry will devour nasturtiums and graze clover, but leave most of the other plants mentioned.) The albizia will also provide wind protection, nitrogen for the soil and mulch for the orange tree. This is an example of an orchard guild.
A guild, then, is an assembly of many different organisms, both plant and animals, which complement each other. It is an extension of companion planting which many people are familiar with, but it can involve animals as shown in the rock guild below. Here, a lizard eats pests in the garden, then seeks shelter in the rocks which, in turn, absorb heat and radiate it to create a warm microclimate for growing plants. This system is mutually beneficial to the plants and animals found there.
Figure 6.20 A rock guild.
Here are a few hints on particular aspects of gardening. Designers will be able to use these ideas as well as incorporating some of them in their own gardens.
• The Clayton’s garden bed when you don’t have a garden bed. Grow your vegetables in plastic or hessian shopping bags (double plastic) with holes in the bottom. This conserves more water than a conventional garden bed.
• There is a need to collect seed from your vegetables and herbs. In the garden, some of these plants should be allowed to complete their life cycle so that they flower and seeds are produced.
Figure 6.21 Shopping bags make ideal garden beds.
• Plant trees and understorey shrubs at the same time. In many cases understorey shrubs cannot establish themselves under existing tall trees.
• Garden beds should only be as wide as your reach, so that you don’t have to walk all over the beds to harvest. Often, a bed one metre wide or one and a half metres wide will allow you to have access all the way round the bed.
Paths are also narrow, usually up to half a metre wide. Sometimes paths have to be wider for wheelbarrow or wheelchair access.
• Bare-rooted tree species are much cheaper and readily available. Many deciduous trees, which are dormant in winter and can be transported without soil, are sold bare-rooted. They are planted straight into the garden at the onset of winter.
As the winter breaks and the warmer spring weather arrives, these trees start to bud and grow.
• Bear in mind that you have more success with some vegetables than others. If this is the case, you may have to change your diet and learn how to use more of these vegetables and less of the ones that you can’t seem to grow.
• Sometimes, wherever mulch is used the soil becomes non-wetting. Water simply runs off its surface and doesn’t penetrate.
To solve this problem you have to get water into the root zone. A piece of pipe or modified cool drink bottle can be positioned alongside the tree and drippers or other irrigation devices can be placed into the bottle. Water percolates down, deep into the soil, minimising loss by evaporation in dry areas.
Figure 6.22 Plastic bottles can be recycled as water suppliers to the root zone.
Alternatively, water repellency is reduced by adding and mixing the clay bentonite to the organic mulches you place around the base of trees.