How to create a pest-free, beautiful organic garden?
© Frances Michaels
There are a series of simple strategies that can be used to create relatively pest-free, beautiful gardens.
These strategies will only work if your attitude to gardening includes a willingness to learn about the
beneficial interactions possible between plants and other forms of life. You also need an acceptance that
'perfect' plants are not the ultimate aim in gardening, and an understanding that every insect is not out to
get you. Creating vibrant, living ecosystems in our backyards will reward us with gardens that are rich and
abundant, full of many forms of life.
Gardens that are regularly sprayed with pesticides, fungicides and herbicides, fed with large amounts of
nitrogenous fertilizers and that have bare soil, actively create the conditions for pest explosions and lack
the natural controls that prevent pest build-ups.
Strategies to reduce pests naturally
1. Plant Selection
Good design is based upon the selection of plants suited to the climate and soil. Getting this right in the
first place will reduce later pest and disease problems. As an example, the time of the year that rain falls
can affect plant health. Plants that evolved in a winter/spring rain regime with a hot/dry autumn tend to be
vulnerable to disease problems if the rain falls at a different time of the year. Grapes Vitis vinifera
tree lucerne Chamaecytisus proliferus
and figs Ficus carica
all evolved in a Mediterranean
climate with a dry summer and will suffer fungal attack in a subtropical climate with a predominantly
2. Healthy Soil
is a major factor in pest balance.
protects the soil and creates habitat for insect
predators such as ground beetles, centipedes and spiders. Organic matter increases biodiversity within the
soil by providing food and habitat for beneficial microorganisms.
is a useful strategy for vegetable gardens as it prevents the
build-up of soil-borne diseases and balances nutrient uptake. This is the practice of growing vegetables from
different plant families in beds the following year. So tomatoes, potatoes or eggplants would not follow each
other as they all belong to the same plant family, Solanaceae.
are crops grown specifically
to build nitrogen and organic matter levels. When used as a crop rotation they can break disease cycles
including root-knot nematodes
root-rot fungal pathogens
are dug into the soil, chemicals
released from the decomposing plants suppress these diseases. Find information on
organic nematode control
3. Attract Insect Eating Birds
Birds such as Robins, Wrens, Honeyeaters, Pardalotes, Willy Wagtails, Thornbills, Flycatchers, Warblers and
Treecreepers are primarily insect feeders and help to control pest problems, including
. To attract birds provide
safe nesting sites, free from predators and with privacy. Dense plantings of native shrubs, in out-of-the-way
corners of the garden will provide important nesting sites for smaller birds, and as a bonus, can be chosen to
provide nectar to attract nectar feeding birds such as Honeyeaters. Including prickly shrubs gives added
protection from cats.
Suitable shrubs include:
- Grevillea species including Grevillea 'Ivanhoe', G. aspleniifolia, G. banksii,
G. 'Boongala Spinebill', G. 'CoastalGlow', G. 'Honey Gem', G. hookeriana, G. 'Kay Williams', G. 'Moonlight'
- Hakea species including Hakea gibbosa, H. salicifolia, H. corymbosa,
H. sericea, H. teretifolia
- Leptospermum species including Leptospermum polygalifolium, L. 'Cardwell',
L. 'Copper Glow', L. petersonii
- Melaleuca species including Melaleuca linariifolia, M. nodosa,
M. styphelioides, M. squarrosa, M. brassii
In an urban landscape nesting sites for birds that require hollow trees are few and far between. It can take
150 years for a tree to develop a hollow large enough to house owls, parrots, gliders, possums and small
insect eating bats. Provision of nesting boxes by urban residents can meet an urgent need, and help to maintain
a rich diversity of wildlife. Small, insectivorous bats are nocturnal feeders, and play an important role in the
control of night flying insects, including
. Sugar Gliders mainly eat insects,
such as leaf-eating beetles
; they also feed on sap-suckers
that excrete honeydew, such as scale
4. Water In The Landscape
Water is an essential element in the landscape, whether it is a birdbath or small pond. Providing a reliable
source of water for birds allows them to nest in the garden. Birdbaths should be placed close to a nearby
refuge of densely foliaged shrubs, to allow easy escape from predators. Fitting any cats with multiple, small
bells, or a mirrored collar, help to prevent decimation of the wildlife population, as does restricting their
Small ponds encourage useful predators such as frogs, which need water to breed. Frogs are very active
nocturnal animals that devour large numbers of pests. Dragonflies prey on flying insects as adults; their
aquatic larvae feed on mosquito wrigglers and other water life. Avoid introducing goldfish to ponds, as they
will eat the tadpoles. Native Pacific Blue-eye fish and Rainbowfish will do less damage to the tadpoles whilst
still helping to control mosquito wrigglers.
5. Know Your Friends
The vast majority of insects occupy ecological niches without ever affecting people, less than 1% of the
resident population of a garden could be considered pests. In fact, many of them are beneficial, being either
predators or parasitoids of other insects. When a predator controls a pest it is termed 'biological control'
and there are a variety of strategies for improving the effectiveness of biological control in the garden.
Being able to recognize the 'good bugs' and adopting an 'innocent until proven guilty' attitude is a useful
beginning. Some of the common 'good bugs' found in the garden are:
- Centipedes, consume slug and snail eggs, and insects pupating in the
ground e.g. fruitfly.
- Spiders are all predatory and are very important beneficial insects;
some such as the Wolf spider actively hunt.
- Predatory mites, these are abundant in the upper layers of the soil,
where they feed on insects and mites, such as Red Spider.
- Ladybeetles, both the adults and larvae feed on aphids, mealy bugs,
scale and other small insects.
- Wasps are nearly all either insect predators or parasitoids. Parasitoids
are the most effective pest controllers as they can lay many eggs within the body of an insect. Many of the
wasps that are important for pest control are tiny.
- Ground beetles feed on caterpillars, grasshopper eggs, aphids, scale and
Other important predators are Lacewings, Hoverflies, Robber Flies, Tachinid Flies, Ichneumons and Assassin Bugs.
To increase the number of beneficial insects in the garden, try to provide them with food and shelter. Avoid
spraying chemical pesticides and reduce the use of 'organic' sprays. Whenever a pesticide is used to control a
pest problem it also kills large numbers of predators, disrupting the ecological balance. Many adult predators
are nectar-feeding, so provide food for the 'good bugs' by growing flowers that are suitable. These are known
as insectary plants and include:
Queen Anne's lace
and daisies. An attractive collection of these
plants is available as the Good Bug Mix
Providing beneficial insects with shelter can range from rocks and logs as part of the landscape, to keeping
the soil mulched, to incorporating perennial plants such as hedges, into the garden design. This will also
increase the habitat for lizards that feed on beetles, cockroaches, grasshoppers, moths, silverfish, slugs and
By regarding the pest alone as the problem, the opportunity is missed to see the real cause of pest problems,
and to design our way out of them. The real problem is that our gardens are often devoid of habitat, regularly
sprayed with biocides and full of plants that are not adapted to their environment. To solve our pest problems
naturally we simply need to establish a garden using the principles of natural ecosystems.