40 degrees is as far I would push a tropical and if its windy 45 degrees

i would agree,40 is about the lowest,but where are you going to keep it in the winter?
this is a VERY fast growing tree,that will grow more than 6 feet a year,and will not flower,so i have heard,outside the tropics,until it is at least 15 years old!
but,with that said,it has FABULOUS leaves!

I soft prune my poinciana to keep it managable.
Last year it was a 7' bean pole, now its about 6.5' tall with about a 5' spread and multi-branched.

I'm not concerned with flowers, I just love the foliage.

Rob

Yea...it is a beautiful tree. I have royal poinciana and jacaranda seedlings of the same age. Both are about the same size in height but the royal poinciana has a much nice "spread"...it kind of looks like the "african" trees from the disney movies. Even without flowers, it is stunning. I plan on keeping one in a pot and making a bonsai into another.

Thanks for the input everyone! Mine is in it's first year, so hadn't thought to much about how big it will get.. I planned on keeping it in a pot also, cause it is a pretty cool looking tree..

I have 2 RP seedlings that are growing very fast in pots. They are about 10 inches tall. I was wondering, what is the best size for transplanting in the ground.

Thank you.

Here's my 5 year old Royal Poinciana. It has survived 2 winters in the ground here in south Orange County, CA. Its surrounded by Caesalpinia pulcherrima (Pride of Barbados) bushes.

it can take at least 30 degrees F. my mom had a huge one that died last year in a bad winter, i think low 20's.

I think Poincianas are not so worried about minimium temperatures of about 40F in the winter months but low day time temperatures in the order of 60F which slowly kill the tree over the winter months. This is based on seeing the tree's performance in Brisbane (50F to 73F in winter) as opposed to Sydney (48F to 63F during the same period). In Brisbane Poincianas thrive and grow everywhere but in Sydney they struggle and rarely become mature flowering trees. However there are a few exceptions on the northern beaches and in the Gosford area. In general I think the key is having a daytime temperature of above 68F during winter and an absence of below freezing temperatures at night.