How to use compost
Compost can be used either as mulch spread on the surface of the ground, or spread a 2.5cm layer
onto the soil and then dig in to the top 15-20cm. Coarser compost is the most suitable as mulch.
Do not leave compost too long (particularly in warm weather) before using it, as nutrients can be lost
Don't plant in pure compost alone. Compost is good for most plants, but doesn't have everything a
plant needs or may be too rich.
NO DIG TECHNIQUES
The ‘no-dig’ method involves building a slow working compost heap straight onto the surface of the soil
as a "raised garden bed", and planting direct into the pile. In the home garden, no-dig gardens can be a
very effective, easy growing method, once established the garden requires minimal maintenance. Esther
Deans in Australia has promoted this style of gardening through her best-selling gardening book: ‘Esther
Dean’s Gardening Book - Growing without Digging’ (no longer in print). The no-dig method has also been
popularised by the permaculture movement.
There are many advantages to be had by using techniques which do not dig or cultivate the soil at all.
Soil life is undisturbed, and as a result, develops a thriving, balanced community. Management
techniques in a no-dig system include mulching for weed control and moisture retention. Organic material
is spread on the surface and left for the abundant soil life to drag it down underground. Diseased plants,
such as mint with rust spores, can be flamed off in spring.
No-dig systems are often set up with raised beds. This confers added benefits. All cultivation, digging,
sowing, planting and so on, can be done from the sides, around the beds, without treading on the soil.
Soil quality therefore is particularly good in such a system.
No dig raised beds - One method
Although timber edges can be used to construct no-dig beds and may help to keep beds intact, this is not
really necessary. Beds can be layered straight on top of the soil, without the use of edging. Straw can
also be placed between the beds to create weed free pathways. Over time the straw in the paths will
decompose, this can then removed and replaced with new straw, the decomposed material is then used
to top up the beds.
A typical no dig garden could be made as follows:
1. Weeds are removed first by mowing, physically removing, burning or some other method.
2. Very thick layers of newspaper (uncoloured) is laid on the surface to inhibit further weed growth (up to
50 sheets thick is not uncommon).
3. A layer of straw or lucerne hay (weed seed free) is placed on top of the newspaper (at least 10 cm
thick). Other materials such as weed-free compost, grass clippings, or sawdust might also be used.
4. The straw or hay is covered with rotted manure to a thickness where the straw or hay can barely be
5. A further 8-12 cm of lucerne hay is placed on top.
6. The surface is sprinkled with blood and bone fertiliser, or chicken manure pellets. Small quantities of
these materials may also be mixed with the hay, sawdust or other materials.
7. Plants are planted direct into the top layer with a few handfuls of good quality compost around the
roots of each when planted.
8. Once the plants are harvested, the materials will have decomposed, just add more layers on top and
plant a new crop. Eventually you will have an amazingly fertile garden full of worms.
Building ‘no dig bed’ retainers.
Use timber to build four walls for each bed. Use a wood which will resist rotting such as red gum, jarrah
(in Australia), oak (very expensive) larch, or sweet chestnut (in UK). Avoid recycled railway sleepers
unless they are untreated. Old ones can contain high levels of creosote residue. Inexpensive pine can be
used, but treat with one of the environmentally acceptable products now on the market. Check with your
certification body to make sure that you are using an acceptable product.
The dimensions of the box can vary but commonly might be 20-30cm or more high, around 1.2 metres
wide and 1-3 metres long. The box can be built straight on top of existing ground whether lawn, bare
earth or even a gravel path. A slight slope is useful as it ensures good drainage. If the site is completely
level, it may also be necessary to drill a few holes near the base of the timber walls to ensure water is not
trapped. Weed growth under and around the box should be cleaned up before setting up the box. This
may be done by, mowing, hand weeding, mulching, or a combination of techniques.
Once built, the box can be filled with good quality soil and commercial (organic) potting compost or some
other soil substitute such as alternate layers of straw and compost from the compost heap. Another mix
could be alternate layers of graded and composted pine bark, manure and soil. The growing medium
must be friable, able to hold moisture, and free of disease and weeds (avoid materials such as grass,
hay, or fresh manures that may hold large quantities of weed seeds).
A commonly used watering technique in these beds is to set a 2 litre plastic bottle (eg. soft drink or milk)
into the centre of the bed below soil level. Cut the top out, and make holes in the side. This can be filled
with water, which will then seep through the holes into the surrounding bed. Mulching the surface may be
desirable to assist with controlling water loss and reducing weeds (Ref: Organic No Dig, No Weed
Gardening by Raymond P. Poincelot - publisher Rodale Press 1986 ISBN
0878576118 – may no longer
be in print)
Most Australian natives will perform better if fertilised. As plants burst into spring growth, (in particular)
they will draw heavily on nutrients in the soil. If inadequate nutrients are present, plant growth can
become stunted. This effect is subtle and not usually noticed until it becomes severe. The nutrient level in
the soil may drop as low as 30 percent below the optimum, before deficiency symptoms (such as
discolouration) appear in the leaves. By this time, the overall growth rate and general health of the plant
has been affected significantly.
What nutrients do plants need?
There are three major nutrients plants need for healthy growth: nitrogen (N), phosphorus (P) and
potassium (K). Nitrogen is responsible for green leafy growth; phosphorus is needed for roots, shoots,
flowers and seed development; potassium promotes stem growth and helps plants resist disease.
Plants also need smaller amounts of calcium, magnesium and sulphur, as well as minute quantities of
a group of nutrients called trace elements (such as iron, zinc, magnesium and boron).
Every plant variety has its own unique set of nutrient requirements. Some plants need more iron and less
phosphorus, others need more phosphorus and less potassium – there are tens of thousands of different
"ideal" nutrient conditions – one for each type of plant.
Choosing the right fertiliser
There is a vast array of fertilisers available and every one is different. Using the wrong fertiliser or the
right fertiliser at the wrong rate can create problems in your garden.
You can get concentrated, fast acting fertilisers (which will feed large amounts of nutrients to the plant
quickly), or slower acting, long term fertilisers - there are many possibilities in between these two
extremes. Avoid direct contact between the roots of a young plant and the stronger fertilisers. Usually a
slower acting fertiliser is more appropriate with planting, particularly in sandy soils where nutrients can be
leached out very quickly. Dynamic Lifter, Osmocote, Nutricote, or something similar is ideal for planting
most plants. Be sure to check the phosphorus content of any fertilisers you intend to use, and avoid using
large amounts of fertilisers containing more than a few percent of phosphorus. Commonly used fertilisers
that have high phosphorus levels include super phosphate, hoof and horn, and blood and bone. The toxic
effects of high phosphorus levels can be offset if balanced with high levels of nitrogen. Generally
phosphorus toxicity is more of a problem in container grown plants than in the soil, where phosphorus is
often immobile ("fixed") in the soil. The addition of fertilisers containing calcium (eg. gypsum, lime) can
make soil phosphorus more readily available. This can sometimes create toxicity problems.
So how do you choose the right one? For a start, it is helpful to know what the various fertiliser terms
Complete fertiliser – These contain a mixture of nitrogen, phosphorus and potassium. Some also contain
calcium and sulphur, and trace elements. The formulations vary according to the plant groups for which
they are designed, eg. flowers, fruit, large trees or lawns. They come in powdered, granular and water-
soluble forms and are a convenient way to provide plants with all the nutrients they are likely to need.
NPK fertilisers – Another name for ‘complete’ fertilisers (N means it contains nitrogen. P means it
contains phosphorus. K means it contains potassium).
Water-soluble fertilisers – These are powdered or liquid complete fertilisers that are applied as a dilute
solution. They generally have high nitrogen content and also contain trace elements. They are useful for
boosting plant growth but only have a short-term effect.
Slow-release or controlled-release fertilisers – These complete fertilisers are designed to release their
nutrients slowly, often up to 12 months. Some are in the form of plant pills others are covered with a
protective coating, eg. Osmocote and Nutricote. They are convenient, safe and easy to use but are more
expensive than other NPK fertilisers. Some organic fertilisers such as blood and bone or rock phosphate
also release nutrients over a long period of time.
Inorganic fertilisers – Artificially-made fertilisers; includes the NPK mixtures.
– A broad term for naturally-occurring fertilisers; includes animal manure and animal
by-products such as blood and bone, mushroom and other composts, green manures, seaweed and
worm casts. The nutrient content is variable, depending on the source of the fertiliser. Some
commercially prepared organic fertilisers such as pelleted manure may have nutrient levels listed on the
When you choose a fertiliser think about the following:
Convenience and ease of use
The type of plants you are fertilising and the time of year
The soil type (clay soils hold fertilisers better than sandy soils)
How quickly you want the plants to grow
How much you’re prepared to spend
Whether you prefer to rely on organic fertilisers.
ORGANIC versus INORGANIC FERTILISERS – which is better?
It makes no difference to the plants whether you apply artificial or organic fertilisers. They simply absorb
whatever nutrients are available in the soil.
BUT there are other important differences:
Inorganic fertilisers release nutrients quickly, producing rapid plant growth
Many inorganic fertilisers can burn plants if applied at high doses
Many inorganic fertilisers have a short-term effect and need to be applied frequently to maintain
Inorganic fertilisers can leave undesirable chemical residues in the soil
Most organic fertilisers are safe to use and won’t burn the plants (except some fresh manures which
should be aged before use)
Most organic fertilisers improve the texture and structure of the soil, thereby improving air and water
uptake (exceptions are powdered organic fertilisers such as blood and bone)
Some organic fertilisers don’t contain many nutrients – their main value is as a soil-improver
Most organic fertilisers if supplied on their own will not supply the complete range of nutrients
essential for plant growth.
Roots start growing before the shoots so feeding should ideally start a few weeks before the foliage
How much fertiliser to apply
Some Australian native plants are well adapted to poor soils, and may be sensitive to strong fertilisers. As
such it is always better to apply too little than too much. You can always add more, but you can't take it
out of the soil and put it back in the bag! In particular, many proteaceae plants are highly sensitive to
Always read the instructions on fertiliser packets. If applying fertiliser to young plants or less hardy plants
(eg. ferns and some indoor plants) you are better to put on less fertiliser.
There are a large number of ready made 'native' fertilisers available from your nursery, garden supplies,
or chain store. Check the labels on the packets or containers to see what the N. P. K. ratios are before
deciding which one/s to use.
Suitable Application Times for Established Natives (these times do not apply to natives grown outside of
Australia – but will vary in accordance with your local climate and seasons.
Problems may be caused in gardens where native plants are growing in or around lawns. Lawns need
regular feeding with fertilisers containing phosphorus, but the natives may be adversely affected by the
high concentration of phosphorus.
In such situations:
Be prepared to have a poor quality lawn
Use lawn fertilisers sparingly and be prepared for some deterioration in plant health.
Use lawn fertilisers which contain rock phosphate instead of superphosphate. This is not as
damaging to natives. It should still only be used sparingly.
Perform the self assessment test titled ‘test 2.2.’
If you answer incorrectly, review the notes and try the test again.
NATIVES ON LOW FERTILITY SOILS
Plants from the following genera have often been recorded growing successfully on low fertility soils (ie.
low in nutrients) in NSW and South West Western Australia. This can be a useful guide in helping you to
select plants for areas with low fertility soils, or in helping you decide how much to fertilise particular
plants. (NOTE: some species from these genera may grow just as well or better on fertile soils).
Actinodium, Agonis, Angophora, Astartea, Baeckea, Beaufortia, Callistemon,
Calothamnus, Calytrix, Chamelaucium, Darwinia, Eremaea, Hypocalymma,
Kunzea, Leptospermum, Melaleuca, Micromyrtus, Regelia, Thryptomene and Verticordia.
From the Proteaceae Family
Banksia, Conospermum, Dryandra, Franklandia, Grevillea, Hakea, Isopogon,
Lambertia, Lomatia, Persoonia, Petrophile, Stirlingia and Telopea.
From the Rutaceae Family
From the Myrtaceae family
Astrolasia, Boronia, Correa, Crowea, Eriostemon, Phebalium and Zieria.
From the Fabaceae Family
Bossiaea, Brachysema, Burtonia, Chorizema, Daviesia, Dillwynia,
Eutaxia, Gompholobium, Goodia, Hardenbergia, Hovea, Jacksonia, Kennedya,
Mirbelia, Pultenaea, Templetonia and Viminaria
From the Epacridaceae Family
Astroloma, Epacris and Leucopogon
PRUNING AUSTRALIAN NATIVES
Though not critical; many Australian natives will benefit from pruning. Some, like many Boronias, will
live and flower for significantly longer if pruned annually. Others can be rejuvenated and the foliage
kept denser and healthy if routinely pruned.
Remove dead tissue will improve both their appearance and health.
Infections (eg. bacteria, fungal diseases; and even insects) attack and gain a foothold in dead (or
weakened) plant tissues with relative ease; then once established, are able to multiply and spread
much more easily into the healthy parts of the plants. Regular pruning can thus be a major way of
controlling diseases in your plants.
Wood rots are a sign that the plant has an infection. Typical signs are soft, crumbling or splitting bark,
and branch dieback. A healthy tree will use its own defence mechanisms to prevent the disease
spreading, but where feasible, it is better to cut off the dead or diseased wood as soon as you notice
Some plants drop their flowers while they’re still fresh; others hold on to the spent flowers for weeks,
even months. Deadheading, the process of cutting off dead flowers from the bush - is beneficial for
When you cut off the dead flowers, you are cutting off dead tissue which could be harbouring
The pruning cuts encourage side shoots to grow so the plant will produce more flowers
You are removing unsightly withered flowers, improving the plant’s appearance
By removing the flowers, you are preventing seeds (and fruits) developing, so the plant has more
energy for growth and flower production.
Most flowering plants will benefit from deadheading, including soft wooded plants (eg. daisies). The
more frequent the deadheading the better, as it encourages more flowers and can reduce the risk of
Is annual pruning enough?
In most cases, an annual prune is sufficient for healthy plants. For most plants, up to one-third of the
growth can be removed at the annual pruning without stressing the plant. (NB. Many plants can
tolerate much more severe pruning – even to ground level; others won’t recover and are best given
frequent light trims.)
At the time of the annual pruning, you should remove any remaining dead flowers and seed heads, as
well as any dead or diseased wood.
In some cases more frequent pruning is beneficial to the plant. For example, although many people
prune roses only once a year, others also give a lighter prune in summer to encourage more flowers
and to cut out any dead or diseased wood.
The same principal applies to all other plants – if the plant is carrying dead wood or showing signs of
disease, don’t wait until the annual pruning to remove the affected parts. Remember, the longer the
diseased or dead wood remains on the plant, the greater the risk of the infection spreading.
Pruning tools should be sharp and clean. Wipe the blades with methylated spirits before and after use
to reduce the risk of spreading disease.
PRUNING TREES and SHRUBS
Native trees are generally similar to most other trees in the way they should be pruned.
Native trees are best pruned when they are young so as to establish well balanced forms which will
be strong when they reach maturity. For many trees there should be one main stem/trunk with other
major branches coming off that, and for others, the habit may involve multi-trunks. Be sure you know
the appropriate growth habit for the tree you are pruning.
Branching should not be at narrow (ie. sharp) angles. When two branches join at a sharp angle, the
join is a weak union and there is a greater likelihood that a split will develop at some stage in the
future, resulting in one branch falling. (If this type of forking is seen on an established tree, then one
side of the tree should be removed. Even if this looks unattractive n the short term, it will grow back
into balance and the tree will be much stronger for the operation).
When a branch is cut from a tree, the cut should be made along a very precise line to minimize the
chance of wood rots developing.
Avoid heavy pruning of Eucalypts. Pruning stimulates dormant buds (ie. epicormic buds) to shoot;
these shoots grow quickly but are only weakly attached to the main trunk or branches. They can
eventually become a problem (ie. falling branches).
How to cut a branch from a tree
Identify the branch bark ridge (ie. the swelling or area of folding on the inside of the crotch where
the two branches join).
Identify the collar of the branch which is to be removed (ie. a swelling at the base of the branch on
Make a cut on the underside, 300 mm or so above the collar, 30% of the way through the branch.
Make a cut on the top, 400 mm or so above the collar. Keep cutting until the branch drops, leaving
only a stub.
Now make a final cut to remove the remaining stub, cutting from a point on the outside of the
branch bark ridge, to a point on the outside edge of the collar.
What is compartmentalisation?
The tissue of a tree is made up of groups of cells forming compartments. Between each compartment;
there is a natural barrier to rot – if the plant is vigorous and healthy, the rot tends to spread through the
compartment, then stop - but if the tree is weak, it may move into the next compartment.
By keeping plants well fed and watered, and ridding them of pests and diseases, you are encouraging
the plants to compartmentalise the spread of disease.