Which climate you live in will affect what you can grow in your garden or window box!
The international climate zone system is designed to identify the minimum expected temperature of an area. It is the same system as used in the northern hemisphere.
Some plants require very specialised environments while others are more tolerant.
However special attention should always be paid to cold areas as many plants are not frost hardy and will simply keel over and die if a frost gets to them.
Most plants in the GardensOnLine database will grow in average Australian conditions, but trying to grow certain plants in the wrong zone is just not worth the effort.
Use this chart of Australia to identify your zone.