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Cultivating Australian Native PlantsThe huge range and diversity of Australian plants means that care must be taken in selecting plants suitable for the conditions that they are to be grown in. This includes soil conditions and moisture content, weather conditions, air movement, position and root competition. A lot of Australian plants are tolerant of variation in conditions from where they naturally grow, and grafting of some selected species can extent this tolerance even further. Maintenance of Australian plants in gardens should not be ignored.
SoilsUnderstand your soil type Soil type is a most important factor influencing which native plants you will be able to grow successfully, so it is essential to know and understand the soil types in your garden before starting to select and plant suitable native plants. Our soils in Victoria are very diverse and it is possible in any one area to have many different soil types.
Most of us classify soil as gravel, sand, sandy loam, loam, clay loam or clay. How to determine your soil type One way is to take a sample to your local Department of Primary Industries office and have it analysed. Another method is to take a slightly moist sample in your hand and squeeze it: ...
Soil structure Soil structure refers to the way soil particles are grouped together. The particles in most soils consolidate into fragments of various sizes. Some soils, such as beach sand, have particles which do not cling together and therefore have no structure. Some clay soils cling together in one solid mass but also lack structure. Well-structured soils break up easily into fragments with definite shapes and sizes. These fragments, being irregular in size and shape, do not completely fill the space they occupy and result in a net work of open spaces and passages which are filled with water, air and plant roots. In fact, an average soil may consist of 40 to 60% open space. The structure of the soil is very important to gardeners. A well-structured soil will easily take in water through the spaces between the particles. Excess water will drain away through the spaces and be replaced by air. Most plants need air and water near their roots to grow well. As many native plants have deep-penetrating roots, it is advisable to take a number of soil samples, one at the surface, another 200mm in depth and the last at 400mm in depth. Surface soils may contain a lot more humus and be much more friable than those underneath. A friable soil is one which can be easily fragmented or broken up. Friable soils allow easy cultivation. These soils contain varying amounts of all sizes of mineral particles, together with organic matter. Will my soil support the plants I want to grow? Having determined your soil type, the next objective is to decide what native plants you want to grow and find out what is the soil type in which they grow naturally. This is very important as some native plants are very particular about soil type and are difficult to grow in other types. For example, Banksias from Western Australia mostly grow in deep sand that has excellent drainage. Soil type and structure are not the only considerations - Is your soil boggy, acidic or alkaline? Plants that grow in boggy soils will grow in well drained soils provided adequate moisture is provided in dry periods, but the reverse will not work. Plants that grow in alkaline soils will grow in acid soils, but the reverse will not work. Most plants around the southern and eastern part of Australia grow in acid soils, however in inland Australia the soils are more likely to be alkaline. A soil's degree of acidity and alkalinity is determined by measuring its "pH". pH measurements are expressed as a number on a scale from 0 to 14 where 7 is neutral, less than 7 is acid and greater than 7 is alkaline. Most soils have pH values between 3.5 and 10. In higher rainfall areas the natural pH of soils typically ranges from 5-7, whereas in drier areas the range is 6.5-9. Soils with pH values of 6.5 to 7.5 are referred to as ‘neutral’. Those with pH less than 6.5 are acidic, and soils with pH less than 5.5 are considered strongly acidic. The acidity of soil can be reduced by adding lime or dolomite, and alkalinity reduced by adding sulphur. To ensure the desired soil pH level is maintained, these treatments may have to be repeated at regular intervals. To determine the pH of your soil you can buy a soil pH testing kit, or take soil samples to your local Department of Primary Industries for analysis. Characteristics of different soil types Gravels have little ability to hold water, retain fertilizers and are naturally very low in plant nutrient. They make an excellent mulch, however, it is difficult for plants to survive in them unless clay and loam are added to hold moisture and nutrients. Deep rooted plants from gravelly soils, once established, will survive in them, because moisture is often present at depth. Sands have similar characteristics to gravel but do retain some moisture, especially as depth increases. Often sandy soils become more compacted as depth increases and tend to have more of a sandstone profile. Their drainage is excellent and many plants from sandy areas such as Western Australian Banksias have adapted to survive in these nutrient-deficient soils. The top 100mm plus of sandy soils can be water-repellent due to wind-blown particles. This can be overcome by digging in humus, clay or loam soil to give a much better water retention profile. Alternatively, the top 100mmm plus can be removed from the proposed planting area to expose the more porous sand below. Soil wetting agents can also be used. Near the sea, calcareous soils may be found which, due to their poor structure, accept very little moisture and it can be very difficult to establish a garden unless using local native plants. Loams are often found where market gardens were once established. Much of south-eastern Melbourne, which is now built on, consists of these soils. Whilst they have good drainage they do retain some moisture and allow the roots of native plants to readily penetrate downwards. Many native plants can easily be grown in these soils. Clays are heavy soils that can retain a lot of moisture, but when they dry out and crack they are hard to dig. They have plenty of plant nutrients. To make clay soils more friable, add gypsum at a rate of 1kg. per square metre repeating the treatment at yearly intervals if necessary. Ripping the soil when the gypsum is added will help it penetrate further down, and adding sand and humus also helps improve friability. Many native plants grow well in clay soils. Soil types across Victoria
The Mallee Most of the area consists of sandhills overlying limestone deposits. The soil is alkaline and poor in nutrients. The low rainfall makes it difficult to grow plants other than from inland areas. Along the Murray River the sands are more loamy and less alkaline and with the aid of
irrigation water the range of native plants which can be grown increases. The summers are
very hot with most of the rainfall occurring in the winter/spring period.
The Wimmera Much of the region has been cleared for farming as the soils are generally heavier. The northern part merges into the Mallee sands and to the west the sandy country is much flatter, with some high ridges. The latter have more loam content in them and combined with a higher rainfall to 500mm, are able to sustain taller shrubs and trees. A large area of the Wimmera consists of heavy clay soils which have a higher proportion of sand grit in them, enabling the sowing of cereal crops, etc. Most soils are still alkaline and the climate consists of hot summers and wet winter/springs, although rainfall can be very erratic.
Northern Country This region stretches from the Loddon River in the west to Yarrawonga in the east. It is mainly flat with numerous streams traversing the country side. The soils are mainly clays but clay loams to loams can be found in fruit growing areas. Along the major rivers there are some sandhill deposits which are excellent for growing Proteaceae species. The summers are hot and generally dry and the winter/springs wet, although the rainfall can be very erratic.
North Eastern Region There is a great variety of soil types here as the region extends from the flat country of the river systems as they flow north to the Murray River, to the alpine areas of Mount Hotham. Here are also the granite outcrops of the Warby Ranges, Strathbogie Ranges and the ranges of the Beechworth and Cudgewa areas. The lower slopes of these ranges often have deep loamy soils with underground moisture. The flat country is generally made up of clay soils but as the streams head back into the hills, better clay loams appear. East of the Strathbogie and Beechworth Ranges, the hills consist of richer clay loam soils and taller trees and shrubs occur. The rainfall is considerably higher. Also in the hills there are some volcanic outcrops of rich red brown friable clay loam soils which sustain lush vegetation. The exposed alpine area is covered in snow in winter and consists of shallow soils in amongst outcrops of shales and schists. Below the snow line the soils become friable clay loams to loams and support forests with thick deposits of leaf and bark matter. The slopes are steep, the rainfall high and much more uniform throughout the year.
Central Highlands This region takes in much of the Great Dividing Range from the Grampians in the west to the high country around Mansfield. The Grampians is a sandstone region and soils around the perimeter slopes consist of loams, which will support a large range of native plants. Further east there is a wide range of rock outcrops from shales to granites and soils vary from clays to loams. Interspersed, and particularly to the north of the great divide, are the goldfield soils characterised by the box ironbark forests and clay loam soils, which have been so extensively dug over that much of the original loam soil has been replaced with clay loams mixed with quartz. In the Kinglake, Gordon/Macedon areas, rich volcanic soils are encountered. The region has a wide variance in rainfall. The northern slopes are characterised by cold, wet winters and hot dry summers whereas the southern slopes have cold, wet winters but the summers are milder, due to westerly changes and some moisture.
Western Plains The volcanic plains of the western district consist mainly of heavy grey/black soils with volcanic rock outcrops. Combined with a higher and more regular rainfall they tend to be more friable at the surface, but crack extensively in summer. Towards the South Australian border the soils are derived from marine deposits and are more sandy to clay loam formation. Along the coast, coastal sand dunes have been formed and at Tower Hill the ash bed has broken down to very friable grey soils.
The Otways and Strzelecki Ranges Here sedimentary rocks have been uplifted and then eroded to form mountain ranges. The soils are generally friable loams to clay loams, rich in humus in forest areas. The area experiences high rainfall and cold winters and plants need good drainage to do well
in these conditions.
Eastern Ranges and Gippsland Lakes District From Warragul to Mallacoota the ranges rise up to join the Alpine areas. The soils are mainly friable clay loams giving way to rocky shale outcrops near the snowline. Interspersed are some volcanic red/brown soils as found on the Errinundra Plateau. Most of this area is national park or forest reserve. Along the river valleys, clay loams have been formed in the Latrobe and MacAlister river systems but near the coast and further east the river systems consist of more loamy soils. Rainfall is high in the mountains north of Warragul but further east, rainfall declines to 700 mm and long periods without rain can be experienced.
Melbourne / Geelong Region
Tips for Growing Australian PlantsMost prefer well drained soils
When adding soil, thoroughly mix it into the existing soil
Eliminate weeds from the planting area
Group together plants needing similar conditions Plants needing full sun rarely survive in shady situations Avoid over watering Most grow well without extra fertiliser
Use mulches and groundcover plants
Lightly prune immediately after flowering
Rejuvenating an old garden? >> Learn from Tony Cavanagh's experiences Low water usage gardening >> How Jan Hall copes with unreliable rainfall and minimal water on tap
Planting NativesThe time to plant natives depends on your climate and the type of plant. Autumn is generally the best time, as it gives the plant time to establish itself before the next summer. Some areas of Victoria, however, are subject to frosts below 2 degrees C and cold conditions. In these areas it is best to plant in the spring after the cold has abated. Also, some native plants are hardy to cold weather and frosts and hence can be planted in the autumn after reasonable rains have occurred. Recommended planting times
If in doubt as to when you should plant, consult your local APS District Group, native nursery, or look to when native plant sales are on in your area as this is a good indication of the best time to plant.
Pruning NativesPruning is an important part of garden maintenance. It is often overlooked and many times when we do start to prune the plant has already grown leggy and hence takes a lot longer to recover its overall greenness and looks unsightly initially. Why prune Promote healthy growth Increase the number of flowers Shape the plant to our liking Extend the life of the plant
Remove diseased wood and damaged material Help small plants to survive long hot summers
When to prune Best time is after the plant has flowered or if you want flowers for indoors - cutting off flowering branchlets is a good method of pruning. Tip pruning can be carried out all the year. It consists of pinching or cutting out the tip of the plant to promote bushiness and increase the number of flowering stems. Trees may require some shaping when they are young - so that you do not have limbs stretching out where you do not want them. Shrubs benefit from regular pruning as it promotes bushiness and the production of more flowering stems. How to prune Correas can be pruned by taking the hedge clippers to them and Anigozanthos species (Kangaroo paws) can be cut right back to 25mm above the ground. Some species such as Banksias must be pruned above the lowest green foliage as they will not reshoot from a leafless stem. When cutting off thicker stems on Grevilleas and Hakeas etc, cut them on an angle and just above a leaf node as this is where the new growth will come from. Make sure your cutting tools are always sharp, and kept clean by regular washing in a disinfectant, otherwise disease organisms could be introduced through damaged tissue.
Plant PropagationThe average home gardener using simple tools and methods can have a lot of fun propagating plants. ASGAP, our national body and the University of New England, have comprehensive information on how to propagate plants - just follow these links
>> Propagation from seed
Precautions Against Frost Damage
Most of Victoria is liable to frost at some time of the year. Areas along the Great Divide and the adjacent slopes are amongst the most frost-prone parts of Australia. Local knowledge is important in planning for frost because features of the landscape such as valleys and hills can channel or divert cold air as it flows downhill, creating microclimates which are significantly more or less frost-prone than the surrounding region.
Further Advice
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Soils are classified into a number of types depending on the particle size. Soil scientists define size classes as: gravel, sand, loam, silt and clay. Gravel particles are larger than 2mm and others go down in 10-fold jumps in fractions of mm.
It is not possible to detail all the soil types to be found across a geographic region as they are
too numerous. Here we will deal with the major soil types. For more precise information on the soil types where you live, consult with your local APS Victoria 
Frost damages many plants and may even kill them, therefore steps to minimise damage need to be a consideration for every garden or plantation.