Originally Posted by spiked1

It also depends how big you want them to grow.
When I was in Sydney which is pretty close climate wise to NZ north island,
I would sometimes plant in december or early january coz I didn't want them growing so tall that the neighbours would see them and I would still end up with 5' or 6' plants.
But if you want huge plants then spring is the go, as soon as the cold nights are gone.
Hope this helps.