You would be able to get away with Heliconia angusta Red, Yellow and Orange forms, Heliconia spissa 'Mexico Red', Heliconia schneideana, Heliconia subulata. these would almost be certain contenders for your area. I have been told that Heliconia rostrata will grow in the warmer parts of the eastern suburbs of Sydney.

Andrew.

Thanks for the suggestions, I'll give it a try.

Concerning gingers, it depends whether you mean it in the narrow sense, i.e. Zingiber officinale, or the broader sense of all members of the ginger family.

I suspect Z. officinale is marginal in Sydney, liable to rot off in autumn and best overwintered indoors wothout too much water. It's possible that some of the other Zingiber spp. may adapt better.

Hedychium would be the genus with the largest number of cold-hardy species. There are even enthusiasts in England who grow some outdoors.

Alpinia also has species that grow vigorously in Sydney, including most of the Australian native spp. But I doubt that the spectactular A. purpurea will do well here, though it may just survive in warmer spots.

I have found that Globba winitii overwinters surprisingly well in Sydney and comes back vigorously every year. This was widely sold as an indoor plant a few years ago.

And Curcuma spp. are also worth trying. Turmeric, C. longa, puts out lots of foliage but never seems to flower (does it in the tropics even?). C. australasica from N. Qld is reported to flower here. I would love to get hold of C. alismatifolia from the hills of N Thailand. In Bangkok parks I have seen it planted in beds like tulips, producing a similar effect when flowering.

There are quite a few other smaller gingers that are cold hardy, e.g. Roscoea and Kaempferia spp.

I have various Gingers growing on the Central Coast. They need a sheltered spot and seem to be doing very well.
Curcuma australasica,enjoys a fair bit of shade and has flowered superbly. The Costas species do well here as well.

I am sure that you could grow many of the less tropical Heliconias in Sydney, particularly if H. angusta does well there. To add to the list of the more cool-hardy Heliconias to seek out, these have all done well for me in northern California coastal conditions, where we do occasionally get colder than you... I never had much luck with growing any of the H. angusta cultivars as outdoor specimens here, and I think it was our lack of summer heat and a little too cool winters, they didn't seem to like it below 12C, and that is right around our typical summer night temps, so they never really took off, but also refused to die.

H. latispatha, H. spissa, H. bougaeana, H. matthieseae, H. aurantiaca, H. scheideana

All of these come from higher elevations of southern Mexico into Central America, and will take some frost and cool nights just above freezing without damage. However, none of them are the classic tropical looking species with really large flowers, except that H. bourgaeana does come close. There are certainly more species that are worth trying as well, but these would be a good start.

As to gingers, there are also many of the Hedychiums that do well, with H. gardnerianum, H. flavescens, H. flavum, H. greenei, H. densiflorum, are fairly common and do well in subtropical, warm temperate climates. Of the Alpinias, A. zerumbet and A. zerumbet variegata are two of the easiest here in northern California.