How to create your own ecosystem
Imagine a garden in which all the plants co-operate with and support each other, living harmoniously throughout the seasons of the year, with no need for artificial pest or weed control. This garden would produce abundant food, flowers and foliage while requiring minimal maintenance. It sounds fanciful, yet this is what occurs in nature.
Of course, natural ecosystems evolve over thousands of years, with a diverse array of plants and animals responding to the challenges placed on them. We hardly have the time to let a garden evolve in the same way. So how can we construct a garden that allows us the time to enjoy this natural abundance?
Understanding the wants and needs of our plants is part of the solution. Just as important is the consideration given to the threats that challenge or the advantages that benefit our plants.
Multiculture, not monoculture
Modern agriculture has developed monocultures whereby one plant species is cultivated to the exclusion of others. It has served us well in the short term, but over hundreds of years productivity is lost and in many instances has resulted in degradation of the soils that support it. We rely on machinery to till the soil and apply fertilisers, herbicides and pesticides. If a disease, pest or even natural event occurs, it threatens all the plants equally. Our home gardens tend to reflect this form of agriculture. We have become accustomed to the aesthetics of multiple plantings and in doing so have become reliant on the same herbicides, pesticides and cultivation techniques that our farmers use.
If you wish to reduce your use of chemicals in the garden, the initial step is to decrease your use of multiple plantings (of the same plants). In some instances, this will not be desirable. You may still want to have a lawn of one species or a uniform hedge. But if you integrate these features into a well-planned, diverse garden, you can reduce or even eliminate your chemical use. You are thus reducing your costs and the cost to the planet in terms of oil. Another benefit, though not always the case, should be a reduction in the labour required to maintain the garden.
Follow the sun
How do we assess the threats or advantages? Start by orientating yourself with the north. It’s important to understand the cycle of the sun. In the southern hemisphere it will be overhead in summer but will angle in from the north in winter. The further south you are, the greater the northern angle. So the northern side of a plant will receive more direct sunlight in winter, as will the soil. This may be desirable for a plant that needs warmth in winter, but not so for a plant that wants a cool or shady aspect. If you face north, the east is to the left and the west to the right. As nights are generally cooler than days, the morning sun from the east is warming up the garden, while the afternoon sun may be cooking it, particularly in summer.
Observe also the reflective surfaces affecting your garden. Metal fences, light-coloured walls, white shadecloth and water reflect light and heat. You may wish to block this light or utilise it in lower light conditions.
Darker features will absorb light and heat. If these are of a solid nature, they will also store heat and may radiate this heat at night. Try to use these features to your benefit with cold-sensitive plants nearer to them.
Next, look at any slopes or raised features in the garden. Air behaves as a fluid “like water”. Being denser, cool air drops and will flow down to the lowest point. If it becomes trapped, you may have a frost hollow. Raised garden beds will remain warmer in cold conditions. This becomes more important the further south you are.
Note the winds
Now, go for a walk. It’s vital to know the prevailing winds in your area. They may be desiccating in summer or bring driving rain. Wind is also the “magic carpet” to transport many plant seeds, insects and other creatures into your garden. Fire, noxious odours, pollution, salt and even noise are all affected by winds.
Wind may be channelled along gullies and valleys or sweep across open areas. Roadways and built structures also form pathways for the wind. Solid surfaces may magnify the wind, while open features such as trees, bushes and shadecloth will suppress wind. Understanding your local wind patterns is important in the placement of plants.
Go with the flow
On this walk, also look at where water may flow towards or away from your garden. Does it drain away or does the soil become saturated? Will it cause erosion? Water is vital to all plant life, but it can be a carrier of disease, pathogens (soil pests), herbicides and pesticides. If desirable, can you harvest water by directing it to your garden? Are there water features that provide habitat for frogs, toads or mosquitoes? Do the local birds, reptiles and bees rely on this water? All these are mobile and may visit your garden. You may want to add your own water feature to extend this habitat.
Talk to the trees
The trees in your area are important features. They will harbour wildlife and block wind and light. The wildlife may be desirable or not. Micro-bats can consume large quantities of insects, as will some birds. Fruit bats, possums and fruit-eating birds may be less desirable. Possibly of greater importance, especially in drier areas, is the water that trees consume. A large gum or pine tree will have a root run extending out two to three times its height and thus may dry out a large area when water is scarce.
And the neighbours
Finally, look at your neighbours’ gardens. Better still, talk to your neighbours. Find out what their chemical use is and also what weeds and bird- and insect-attracting plants they have. Aerial spray drift can be a serious problem, as can the movement of chemicals in water underground. Do they have plants that block the wind or sunlight? What are they growing successfully and how are they achieving this? It may take some time to find out all this, but the more you can find out the more successful your garden is likely to be.
Armed with all this information you can now go back to your own garden. The plants you choose will vary enormously, so let’s start with some basics. Start with plants suited to your area and soil type. If you are unsure, seek advice from neighbours, local garden centres or written material. Local libraries carry a range of gardening books and will usually acquire books if requested. The internet is a wealth of information — sometimes too much, so stick to accredited sites.
Companion planting is also an effective way to get the most from your garden and plants.
Most herbs have insect-repelling and -attracting properties. Placing these near another plant may not be required if you want to attract more mobile insects, for instance bees. It may be of more use to place one or two bee-attracting plants in a position open to the sun for warmth that is protected from the wind and close to some permanent water, particularly in a drier environment. In my garden, lavender performs this task admirably, as it flowers year round so the bees have a constant supply of pollen, even in the cooler months. They also have permanent water to visit in the drier months.
Plants with open flowers, such as daisies, dandelion, parsley, dill, coriander and the like, provide pollen as a valuable food source, not only for bees but also for many of the beneficial parasitic wasps that prey on insect pests. These plants should be spread throughout your garden as many of these wasps are tiny and will fly only short distances. Larger predators such as lacewings and hoverflies also feed on the pollen. Many of these plants are seasonal, so choose from a range of them. By allowing them to flower, you will produce your own seed, which you can sprinkle around your garden and even share with neighbours and friends. You can thus become a seedsaver and a local resource!
Not so bad insects
Insect-attracting plants may also attract less desirable species. In nature’s balance, they are food for other animals both big and small and so should not be considered totally undesirable. However, there may be times of the year when the pest species get out of control. Many plants can be used as “trap plants”. These plants may be sacrificial, as the nasturtiums in my garden are. I allow cabbage white butterfly caterpillars to feast on them while keeping the caterpillars off my cabbages and other brassicas. This provides a food source for the parasitic wasps that attack the cabbage white caterpillars.
There are many other examples of this concept with aphids on sow thistle and a host of other plants, harlequin bugs on sunflowers and so on. It should not be necessary to spray with broad-spectrum chemicals in any garden as you will also kill off the beneficial insects, mites and spiders.
Insect-repellent herbs rely on their scent to confuse or repel insects. Many are perennial, so require permanent placement. If you have prevailing winds that bring in the bugs, look to place them at the first point of contact as well as throughout the garden. Larger shrubs such as wormwood, rosemary and some of the natives such as tea-tree won’t welcome new arrivals. Lower-growing herbs such as thyme, oregano and the alliums, onion and garlic can be spread through your garden. They can also be placed along borders for a visual effect.
Below the surface
Broad, soft-leafed plants are generally soil-building. Worms utilise the leaves as food. This greatly improves the health of soils as worm casts are not only nutritious but contain many beneficial bacteria and fungi for plant growth. In addition, many of these are deep-rooted and bring minerals to the surface. When these roots die off, worms will eat them, following them down, aerating the deeper layers of the soil.
Biodiversity has as much effect below the soil as above. Many plant roots also prevent the spread of pathogens below the soil surface. Marigold is well known for its unpleasant effect on soil nematodes, which attack other plants’ roots. Mycorrhiza, the non-pathogenic fungi in the soil, provide nutrients to plant roots and also share nutrients between plants. Biodiversity and healthy soils assist this.
Bring on the skinks
Habitat for vertebrates other than birds is an important aspect of any bio-diverse garden. You may wish to construct a rockery to encourage local skinks and geckoes which, along with frogs, make very useful additions to any garden. In drier areas, a frog pond is a must. In wetter areas, plants such as bromeliads and orchids will provide habitat for frogs. Being active during the wetter periods means they are generally very effective in clearing up slugs and snails by consuming their eggs. Of course, they consume a wide variety of beneficial and pest insects. Tadpoles will also eat mosquito larvae in ponds, as will fish.
So you can see that the basics of companion planting rely on providing a diverse habitat for the various organisms in your garden — plant, bacteria, fungi and animal. We will never replicate the complexity that nature achieves. However, in moving towards this complexity you can certainly reduce your reliance on pesticides and herbicides. In doing so, I trust you will be making it a safer place for all.
Read about it
- Companion Gardening in Australia by Judith Collins
- Companion Planting in Australia by Ken Gilroy
- The Garden Guardians by Jane Davenport
- Roses Love Garlic by Louise Riotte
- Designing and Maintaining Your Edible Landscape Naturally by Robert Kourik
- The Seed Savers handbook by Michel and Jude Fanton
Harry Harrison is a veterinary surgeon with an passion for the natural world and is thus a permaculturalist and organic gardener. Community gardens, seed saving and the Rare Fruit Society of South Australia also make up his world. email contact firstname.lastname@example.org
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