Tibouchina {Blue Moon} $15

T[bouchinas originated in South America, where they grow over a wide diversity of climates, and that means they'll do the same in Australia. They don't like hard frosts, but give them a warmish spot and they'll do well from Melbourne to Cairns.

They do need pruning, otherwise they will grow into a fairly large tree. Afer they finish flowering, prune the plant back. Delaying the pruning means you throw the whole flowering season out of kilter and this will result in spasmodic flowering.

Tibouchinas do well because there's not a pest or disease that comes near them. If you've got one I'll guarantee you'll be thrilled to bits..