General Tips for Growing a Native Garden

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This page provides a list of gardening tips, including cultivation, soil types, fertilising and mulching, and water-wise gardening, to make sure that your native garden is a success.

Cultivation

Many people think Australian native plants are difficult to grow, but they aren’t really. As with all plants, it mainly depends on matching suitable plants to a particular garden environment. If you grow indigenous plants (those natural to your area) that are suited to your garden's location and have healthy soil, these plants will grow quite easily.

However, there may be some groups of plants or individual species that are difficult to propagate or cultivate in your garden. For example, plants from different climatic zones to Sydney may be difficult to propagate unless their preferred growing conditions can be mimicked in the garden.

Growing difficult plants

Many difficult plants can be successfully grown in containers. Alternatively, you may need to put in substantial effort to alter soil conditions to suit them. For example, the Sydney Rock Rose, Boronia serrulata, is a small shrub found in sandstone areas but it is usually difficult to grow in the garden. In some cases, success has been had by creating garden beds with buried sandstone rocks and rubble and planting into this.

Soils

Australian soils are ancient and are generally low in fertility and organic matter. The distribution of many native plants is strongly influenced by the type of soil in an area, e.g. sandstone or Cumberland clays in Sydney, and its position in the landscape (ridge tops versus gullies, north versus south-facing slopes). Distribution will also reflect differences in combinations of light and moisture together with soil type.

Most Australian soils are neutral or slightly acidic with a pH between 5.5 and 7.0 but some, especially in West and South Australia, are alkaline (pH over 7.0). To find out what pH your soil has, speak to your local nursery, which may sell do-it-yourself soil testing kits or provide a soil testing service.

Modifying soil conditions

  • Clay soils - dig in compost or manure and add gypsum to make the soil more friable. Raising the soil level slightly will also assist drainage. Often the soil level only needs to be raised by about 30 cm.
  • Sandy soils - dig in organic matter and keep well mulched.

Fertilising

Australian native plants have evolved in poor soils and are very sensitive to artificial fertilisers, especially phosphorus. Generally, clay soils are naturally fertile and shouldn't require any added fertiliser, while sandy soils are low in fertility as nutrients leach out with fast drainage. Only use low-phosphorus fertilizers especially formulated for Australian native plants or mulch instead. Both clay and sandy soil types respond well to thick layers of organic matter used as mulch.

Mulching

What does mulching do?
Mulch helps to maintain soil moisture and reduces or eliminates the need to water artificially. In addition, as mulch breaks down, nitrogen and potassium are replenished in sandy soils. Mulch also provides humus (nutrient-rich earth formed when plant or animal material decays), which improves the soil, and can reduce weed growth.

What can you use?
Any organic material that is free of disease is useful. Use leaf fall, grass clippings and path sweepings as mulch on garden beds. See what is available at your local nursery or local council, and ask what they recommend. You could invest in a home mulcher and turn all your garden prunings into mulch, or a cheaper option is to just keep all garden clippings reasonably small and put them straight back onto the garden. Nothing needs to be wasted.

How much should you use?
Apply mulch to at least 100 mm in depth, which should last all year. Be careful that it isn't piled up against plant stems or trunks as this can encourage fungal growth and disease.

When should you mulch?
Mulch just after rain when the ground is already moist. This helps to keep the moisture in. How often you mulch will depend on the type of mulch you use, how quickly it breaks down and needs replacing, and the reason you are mulching. If for food, mulch twice a year in spring and autumn; if to retain moisture, a thick layer once a year should be sufficient.

Pruning

Many native plants benefit from regular pruning, especially tip-pruning (pinching off the growing tips). This helps to keep them compact and dense, which is most important when planting for small birds. The best times to do this depends on the plant and why you are growing it; if it is providing nectar, tip-prune after flowering has ceased; if seeds or fruit are the benefit, prune after these have finished.

Water-wise gardening

Many Australian plants use less water than introduced plants, but most still require some moisture to grow well. There are a number of ways to reduce the amount of water you use:

  • Plant small plants and encourage them to develop a deep root system by watering minimally (just keeping the soil moist) right from the beginning. As they mature, the deeper root system will allow them to survive on less water and tolerate droughts more successfully. Tube stock from nurseries are a good size to plant, are cheaper and will establish and settle into their new position faster than older plants.
  • Mulch with an organic mulch at least annually. This helps both to retain moisture and to prevent sandy soils from becoming water repellent (water is unable to soak in and runs off the top of the soil), through the action of micro-organisms in the mulch.
  • Plant appropriate plants that are suited to the conditions in your garden and don't require excessive care to keep them healthy.
  • Wetting agents or surfactants can be applied to the soil, which can help to reduce water repellence and help the soil to retain moisture. Discuss their use with your local nursery.
  • Install water tanks and gather your own water supply which is free of chlorine and other additives used in city water supplies. It can be used directly on the garden or in garden ponds containing fish or frogs.

Water-wise design

There are a number of garden designs which also reduce the use of water For example, if the soil in a garden bed is simply raised as a mound, over time it will pack down and water will not readily infiltrate and the plants will suffer. One more useful method is to build a system of raised beds and swales (artificial or natural hollows for drainage of surface water) so that the water gathers in the low areas and soaks into the raised beds. Designing and landscaping your garden to direct water either into garden beds or to capture it during storms in low-lying parts of the garden will make a big difference to your garden's ability to retain moisture in the soil.

Diseases and pests

Keeping your garden clean and healthy is the most important method of avoiding health problems in your plants. Healthy plants are less likely to get badly attacked by pests or diseases. Good gardening practices, such as keeping your soil healthy and using plenty of organic matter as mulch to help retain moisture, will help to ensure this.

Don't worry if a plant is looking less than perfect
If an Australian native plant is attacked by insects it might look a bit shabby, but for the plant, it may be like having a good prune. If left alone, they often recover and look much better for the trim.

Encourage insects into your garden
Some insects are leaf eaters or may bore holes in stems. But other insects will prey on these damaging insects and will eventually get rid of them. The more insects there are, the more likely you will be to have a balance of good and bad insects. You will also have more birds.

Encourage birds into your garden
The best controllers of insect pests are birds. Many birds are insectivorous, including most of the smaller birds and the honeyeaters. So, the more birds you have and the greater diversity of bird species that visit your garden, the fewer problems you will have with insect pests.

Grow indigenous Australian native plants
Australian native plants, particularly those that are indigenous (grow naturally) to your area, will usually have their own means of managing and overcoming pests and diseases. For example, many native plants also have their own defense mechanisms such as using sap to inhibit stem or trunk boring insects.

Avoid using sprays and chemicals
Try not to use sprays and chemicals unless you really have to. Generally the more you use the more you have to use, so once you start it is much harder to stop. Using a chemical may solve one problem but often creates another, such as toxic run-off. Of course, not all nurseries will give you this advice, as they want to sell the sprays and chemicals, but ethical garden advisers should.

What should you do when a problem arises?
Firstly, try and diagnose what the real problem is and what is causing it. Many books give advice about this or you can take a sample/picture of the plant to your local nursery and seek advice from their gardening adviser.

What about fungal diseases and root rot?
Many fungi are good fungi and some, known as mycorrizhae, have symbiotic (mutually beneficial) relationships with Australian native plants, helping them to survive in Australia's nutrient-poor soils. These can be encouraged by having a healthy organic garden free of chemicals and artificial fertilisers. However, some fungi do cause diseases, particularly of the roots, which may cause wilting or sudden death. These can be hard to treat. If you think this may be the problem, take a sample to your local nursery and get advice on the disease and its treatment.

Death by age
Not all plant deaths mean disease. Many Australian native plants are quite short lived, especially those which also grow quickly such as many of the Acacias (wattles). They may die slowly or quite suddenly. You can plan for this; if you have a favorite plant that you know may only live for a while, plan to keep planting them on a regular basis so you always have some in your garden.

Death by an unknown factor
Some Australian plants are very particular about their requirements and die for no apparent reason. Any one or a combination of factors could be the cause. One way of avoiding a repeat performance is not to try and grow that plant again or, if you really love it, you may need to provide it with very specific conditions. When you are trying out new plants in your garden, it is a good idea to only get one or two to start with. If they do well and thrive, buy more. If they don't, try something else.

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