There are many types of fruit trees that will grow and thrive in the southern hemisphere climates of Australia--it is simply a matter of selecting the proper fruit-bearing tree for the proper region and climate that you wish to grow it in. These trees are not particularly difficult to grow, but it does take a bit of planning to ensure that you are getting the best results out of your fruit trees every year.
Choose fruit trees that are appropriate to the climate in which you are living. As a general rule, citrus and deciduous fruit trees do well throughout the sunnier and warmer parts of Australia. Once you get into the cooler climate areas, such as Melbourne, you can have success with some of the tropical varieties of fruit trees.
Plant several varieties of the same type of fruit tree near one another. In order for most fruit trees to bear fruit, they require cross-pollination from similar fruit-bearing trees, so as long as you live in a portion of Australia with a reasonable bee population, then you shouldn't have a problem. If you do not have space for multiple trees, then make sure that you get self-pollinating trees when purchasing the sapling from your local nursery.
Place a layer of mulch around the base of the fruit trees once they are planted. The mulch will discourage the growth of weeds and other vegetation that would compete with the fruit tree for root space and soil nutrients. It is best to refresh your mulch twice a year--spring and fall--every year for the life of your fruit tree. Don't forget that due to being in the southern hemisphere, the seasons in Australia are opposite of what most people from the northern hemisphere are used to.
Protect your fruit trees. Insects and various forms of wildlife can be detrimental to the growth and well being of your fruit trees. To prevent this, it is best to spray your trees once a year, generally in winter, with a vegetation-safe insecticide. Again, keep in mind that winter in Australia falls during what most people in the northern hemisphere are used to as summer. For wildlife problems, you can place tree guards around the base of the trees to keep larger fauna from eating the bark and make sure to harvest in a timely manner to keep from attracting smaller, tree-dwelling pests.
Prune your fruit trees yearly. Pruning of fruit trees is best done during the winter-- July or August in Australia--while the tree is dormant. Yearly pruning will help assure that your fruit tree remains healthy and producing at optimal levels.
Wait patiently. Fruit trees generally take several years to begin producing fruit. It is best to check before beginning to see the maturation cycle of the particular fruit tree you want to plant.