Poincianas like a very dry dry season and a wet season in the summer. They tend to grow and flower best when they're away from gardens and aren't getting any irrigation. Losing the leaves over the winter (dry season) is normal. Having some leaves come back in the winter is a good indication it's getting too much water (any water). The Poinciana supplier should have advised you about that as I assume he helped you plant it where it is.

Hi thanks for your reply. There are quite a lot of poincianas in my suburb and all are completely covered in foliage. He advised that i should water it a few times a week to help it cope with transplant and that in this area poincianas don't really drop all their leaves and are in fact only semi-deciduous as the drop and grow new leaves at the immediately. This is evident by the fully leaved poincianas all around. Also we've had a fair bit of rain this winter and temperatures haven't been below 10degrees Celsius at night and 20 during the day. I will stop the irrigation water and see if it perks up.

There's always a difficult balancing act between watering and over watering after transplants. There's always some damage to roots. Infections can get in and the damaged root system can't take up as much water as it used to. But 10 months should be a reasonable time to have settled in. I'm near Darwin so today (mid winter) maximum temperature was 35.1C, minimum was 17.9C. Last rain was in April so it's very dry now. Poincianas are totally leafless, but when we get towards the end of the dry season they'll be totally covered with flowers and still no leaves. When the leaves come the flowers start to fall off. The best displays of flowers are from trees away from gardens so their roots don't pick up any water seepage. Where they do get some irrigation they don't lose all their leaves and they have a poor showing of flowers. Common wisdom here is that Poincianas need neglect to perform their best.