This course is designed as a foundation for people working as gardeners, and for some can be a stepping stone to developing a garden maintenance business, or to further studies leading to a career in horticultural management, education or media.
You can start any time, work at your own pace and study from home, while traveling or wherever it suits.
There is a direct relationship between plant health, growth and soil organic matter. It is well known that plants growing in soil with little or no organic matter grow very poorly. The key for any garden, any landscape or any vegetable plot is the organic content of the soil.
Plant growth is directly affected by the type of soil the plants are grown in. The majority of plants depend on soil to provide nutrition, physical support (i.e. a place for roots to anchor), water and air. The exceptions to this are those plants that are known as epiphytes. These grow in such places, as tree trunks, on rocks, on or fallen logs.
Soil is made up of:
- Water containing varying amounts and types of nutrients (and other chemicals) in solution.
These "particles" are further divided into:
- Mineral particles of various sizes including clays, silts and sands.
- Organic material in varying states of decomposition.
- Living organisms mostly microscopic, but also including insects, earthworms, nematodes, etc.
These things affect the soil's ability to grow plants. It is possible to grow some plants in soils without living organisms, organic matter or mineral particles; but plant roots must have air, water and nutrients. Generally, however, you will require some amount of each of the above components to get the best growth from your plant.
MAINTENANCE OF SOIL
Soil is constantly affected by all that goes on around it. Its physical properties can be affected by traffic and handling. Its chemical properties can be changed by things added to soil, and by plants removing chemicals. These will in turn affect the biological properties of the soil.
One of the main problems with changing physical properties is the reduction of air in the soil.
There are two basic ways this happens.
- With changes in drainage patterns by altering the landscape so that water will run to certain areas and sit there.
- By the soil being compacted by traffic or such practices as cultivating the soil when it is wet.
These problems can be solved by avoiding compaction due to walking on or digging soil in wet conditions, putting drainage pipes in for waterlogging and by aerating the soil by digging it over when reasonably dry and incorporating organic matter. Lawns and similar areas where digging is impracticable can be aerated by removing small cores of soil at regular intervals. Sand can be incorporated into the soil by means of cutting slits in the soil surface, and then adding sand that has pore spaces of around 10-30%.
Gypsum is commonly applied to hard packed or poorly structured clay soils. It has the ability to cause clay particles to aggregate together in small crumbs (or peds), thereby improving structure. It is also used to reclaim saline soils with high sodium levels (known as sodic soils). Gypsum contains around 23-25% calcium and approximately 15% sulphur - it will not affect soil pH to any great extent. However it should not be used on non-sodic soils and soil structure will be compromised as a result.
Nutrient levels can be exhausted with time, as plants take up what they need and by leaching from watering. This can be easily rectified with fertilisers. Additions to the soil in the form of contaminates may take a bit more work. Lighter spills of non-toxic substances can be washed out of the soil by excessive watering, but spills of heavier substances (such as lime, pesticides or petrol) may require the removal of the affected earth before the substance spreads and changes the soils properties (e.g. pH).
When Soils are Appropriate, Plants are Healthier
When plants are healthier; they can fend off attack by pest and disease; recover better when damaged or affected by harsh weather. A big part of good garden maintenance is maintaining good plant health; and a major way of maximizing the plant health is to ensure soils are in a condition that best suits the plants growing in them.
Matching the plant species to the soil you grow it in, is just as much a part of good practice; as it is to improve the soil through management of it's physical and chemical properties.
If your soil is acidic, for instance; it is more appropriate to grow plants that love acid soil, rather than change it from being acidic. Similarly, if it is too wet, too dry, ar too alkaline; choose to grow the plants that are appropriate to the soil, rather than changing the soil.
WORKING WITH LIME SOILS
Some soils have a higher pH than others (i.e. they are alkaline), and that can severely restrict the type of plants which will grow there.
In very simple terms, pH is a measure of the balance between particles which have a negative electrical charge and those with a positive charge.
On a scale of 1 to 14, a soil with a pH of 7 has an even balance of negative and positive particles. Soils below 7 are acid. Soils above 7 are alkaline, and are commonly called lime soils because it is most often lime in the soil that causes them to be alkaline.
Lime is commonly a problem in the following places:
- Coastal Soils in coastal areas which contain a lot of shell grit are usually alkaline.
- Limestone soils Soils in areas containing a lot of limestone (eg: Around Adelaide, extensive areas in South west Western Australia, near Mildura in Victoria, etc.).
- Old building Sites Cement & plaster are often dumped on building sites.
These materials can be covered up when building is done lime leaches out into the soil and surrounding areas become alkaline. etc.
Dealing with lime soils:
You can either...
a/ Change (lower) pH
This can be achieved in the following ways:
- By adding acidifying agents to the soil such as powdered sulphur. For soils that are alkaline due to the presence of limestone or shell grit you will need regular long term applications of such additives. For soils where builders rubble, etc. is the problem you may need to apply additives for several years until the lime present has been completely counteracted.
- The incorporation of organic matter into the soil and the use of organic mulches will generally lower pH levels. This method is slower acting than the previous method, but generally longer lasting. There are also additional benefits of increased nutrient levels, improved soil structure, etc.
b/ Use lime loving or tolerant plants
Shrubs that grow in Lime Soils
- Arbutus unedo
- Atriplex nummularia (Saltbush)
- Banksia ashbyi
- Banksia ornata
- Brachyscome iberidifolia
- Brachysema lanceolatum
- Callistemon Harkness Hybrid
- Calocephalus brownii (Cushion Bush)
- Calothamnus quadrifidus
- Caryopteris (Blue Spirea)
- Casuarina humilis
- Chamelaucium uncinatum (Geraldton wax)
- Chrysanthemum frutescens
- Clianthus formosus (Sturt's Desert Pea)
- Correa alba
- Correa decumbens
- Correa mannii
- Diplolaena (most)
- Echium candicans
- Epacris impressa
- Eremophila glabra
- Grevillea ilicifolia (NB: Most Grevilleas are not suited)
- Grevillea leucopteris
- Grevillea pauciflora
- Grevillea vestita
- Hibiscus syriacus
- Juniperus horizontalis
- Juniperus Pfitzerana group varieties
- Juniperus sargentii
- Leptospermum lavaegatum
- Melaleuca hypericifolia
- Melaleuca nesophila
- Melaleuca wilsonii
- Myoporum insulare (Boobialla)
- Solanum rantonnetii
- Tecomaria capensis
Trees Which Grow in Lime Soils
- Araucaria heterophylla
- Banksias (Most W.A. types)
- Brachychiton populneus
- Brachychiton rupestris
- Casuarina cristata
- Cercis siliquastrum
- Eriobotrya japonica (Loquat)
- Erythrina (Coral Tree)
- Eucalyptus camaldulensis
- E. cladocalyx nana
- E. lehmannii
- E. forrestiana
- E. gomphocephala
- E. leucoxylon rosea
- Juniperus chinensis
- Juniperus communis
- Feijoa selloana (Guava)
- Malus sp.
- Fraxinus oxycarpa
- Melia azaderach
- Pittosporum phillyraeoides
- Populus sp.
- Prunus sp.
- Punica (pomegranate)
LIME LOVING PLANTS ON NON LIME SOILS
Many of Australia's most spectacular plants are from South west W.A. where soils are frequently acid sands on top of limestone. Many of these plants are difficult to grow in the eastern states. Some have been grown successfully, however, using a method known as the limestone underlay technique. This is simply placing a 10 15 cm layer of crushed limestone, limestone chip, or builders rubble high in cement, plaster or mortar, below 25 30 cm of top soil. The high pH of the underlying layer is believed to inhibit fungal diseases such as Phytophthora cinnamomi (dieback disease).
AFTER THIS COURSE
Lots of people become gardeners, but few become good gardeners - largely because most tend to assume gardening is something that requires relatively little skills.
Gardening does however require a basic understanding of plant identification, pruning, mowing lawns, using fertilisers and controlling pests and diseases
- If you don't know the plants you are dealing with you will plant them in the wrong place and as a result, they won't look as good, or live as long.
- If you don't know the difference between a good plant and a weed, you may be removing good plants and not removing weeds
- If you prune plants in the wrong way or at the wrong time, you can kill them, or cause them to not produce flowers or fruit.
- If you mow lawns incorrectly, you can encourage weeds, pests, or cause the lawn grass plants to become sick or unsightly
- If you don't know about pests and disease, you are likely to overlook problems, or misdiagnose them when they are insignificant and that can lead to problems that are more difficult and expensive to control.
People do want to employ gardeners but all too often, they will dismiss a gardener or avoid employing one, because these issues (and others like these) become a repeated concern.
If you do this course you will have the knowledge to avoid making mistakes like this, and that will make your skills a very marketable commodity.
How Will You Benefit from this Course?
- Build self confidence to do jobs you may have avoided in the past
- Fast track business or employment opportunities in gardening
- Save time -no time and money lost traveling to college
- Take control over when, where and speed of your studying
- Support from a team of experienced professional horticulture tutors who have worked across both Australia and the UK
- Learn to understand garden maintenance. Make better decisions, be more productive and effective in all you do.
- Build connections with industry and become aware of new products, ideas, techniques and opportunities.
- As a graduate, receive free career and business advice from our horticultural staff -yours for the asking.
- Start a lawn mowing or garden care business
- Buy an established gardening business
- Get a gardening or groundsman job
- Acquire knowledge and skills that will make you more attractive to employers or clients
- Work in a plant nursery, landscape or other gardening business
- Work in allied trades, horticultural sales or marketing