Sounds like a pest problem to me. I would start spraying them with some soapy water and try to keep them growing in a warm place. If you let them go dormant, there's a good chance they won't come back. At least that has been my experience with stressed heliconias.

Here is a link to another thread I have read. the pictures here are similar to what my heliconias are looking like however if you could give me some other possibilities that would be good so that I can hopefully get rid of the problem.

If it spider mites, what is a good herbal mix that I can use or make my self to kill them off as I do not like to use chemicals.

Cheers guys.

http://forums.gardenweb.com/forums/load/tropical/msg031821213555.html

Heliconias are very easy to grow especially Heliconia rostrata. They are very large plants which like hummidity and copious amounts of water. Could it be that your pots are too small and you are getting fertilizer burn or that they are staying too wet in your pots and you have root rot. Here in S.Florida(your climate is similar unless you are high up in the mountains) I grow Heliconia in the ground-they are far to large for pot culture IMO.
If you look at the undersides of the leaves you can see spider mites if they are there-tiny little dark redish specks and they cause the top surface of the leaves to have a silvery appearance. You can blast them off with the hose or if a heavy infestation spray the undersides of the leaves with an insecticidal soap- this is completely harmless, except to the spider mites. Either method you will have to repeat several times. Unless you have had a very dry summer I don't think it is likely to be spider mites-they are only usually a problem in dry weather.The only insect pest I have really noticed on Heliconia is the mealy bug. I have found these in the roots and in the axils of the leaves where they are attached to the stems, but the plants are so vigorous they they are not much of a problem.
I would take your plants out of the pots,wash off the soil and check for mealy bugs in the roots and leaf axils etc and cut of any rotten or dead roots and any rotten rhyzome. I would then plant them in the garden in either full sun or semi-sun in a spot where there is plenty of room, rich loamy well-draining soil where they will get plenty of water(the more sun the more water) and fertilize a couple of times a year(not till after they get growing, in your spring)-although I find they are such rampant growers that I don't bother to fertilize. The only problem for you now, at this time of year, is that they really prefer to be dug up,divided etc in the spring and you are now going into winter. However if they look like they are not happy perhaps it is better to do something!
After 1 year you should have some big lush growths so if you have had adequate humidity and given them plenty of water I would suspect root problems possibly caused by your growing method.
Heliconia rostrata can take quite a bit of cold so unless you are up in the mountains you should not have a problem.
Hope this helps and good luck.

Gatecrasher,

The climate around Noosa is ideal for growing a wide range of Heliconias so I that is not your problem. As for dying off over winter, it shouldn't happen. Heliconia rostrata and Heliconia stricta 'Jamaican Dwarf' shouldn't even show any cold marks on their leaves. Your Heliconia rostrata will need to 'overwinter' its growths for you to obtain any flowers. As said by one of the Florida people these are quite large plants and although they will flower in pots they do much better in the ground.

As for spider mite. I haven't ever really had a problem with it on Heliconias (and I have heaps of them). The only time I have found mites on any of my heliconias is when they have been growing under the eaves or under a plastic greenhouse. They have been on other plants in my garden (mainly Cordylines) but rarely touch Heliconias out in the open. If you do get them I like to use 2 methods to get rid of them.
1) Lux flakes mixed in warm water and sprayed on to the leaves smoothers the mites. Do this at 4 to 5 day intervals to destroy the breeding cycle.
2) Blast the leaves with the hose. This removes adult mites and I believe also removes the eggs.

Hope this helps,
Andrew.

BTW: you might want to look at the website of the International Tropical Foliage and Garden Society Inc at www.itfgs.org

Here is a link that might be useful: The International Tropical Foliage and Garden Society Inc

In Fiji we are growing Root strata Heliconias for the market as cut flowers. Can anyone tell me how to get rid of black marks on the flowers please. Also other types of heliconia with marks on their stems. I would appreciate any help thanks.