Pentas lanceolata hybrids and cultivars
This shrubby perennial is an outstanding plant for Qld if you're looking for something that's easy to grow and produces flowers in the white/pink/mauve/red colour range over a long period.
Older varieties can grow over a metre tall, and will sprawl if not cut back occasionally. A good time to do this is just as they are coming back into vigorous growth in spring, but you might feel the need to give vigorous specimens an additional pruning once or twice during the warmer months.
Aome of the new varieties are more compact. Look for Butterfly, Graffiti and Kaleidoscope series.
Cutting back during the growing season may mean sacrificing some flowers, but they don't have to go to waste - put them in a vase in the house.
Newer varieties have been bred for a more compact form and will need much less pruning. You nevertheless might like to snip off the dead flower heads for is you want to be extra-neat.
Grow in full sun or semi shade. They are relatively undemanding with respect to water and fertiliser. They're perennial in the frost-free parts of Qld climate, but are treated as annual bedding plants in colder parts of the world
Pentas can be propagated from seed (allowing for that fact that seedlings may differ from parents), but cuttings are easy to strike.
The so-called "Giant Pentas" is another plant, Carphalea kirondron.