If they're meant to live outdoors and go dormant to rest up for spring, leave them there. They won't survive otherwise. If they're not normally used for bonsai (for the reasons you gave, and which I agree with), why look for a hard time - there are so many other trees out there.

From my understanding, they go dormant in nature from dry spells, and if they're used as a large container plant, they might go dormant if being brought inside during the winter. They don't necessarily NEED to go dormant from what I've read, though.

Anyway, barring turning it into a true bonsai, are there any bonsai techniques I could use to keep the tree a more manageable size?

Prune old woody circling roots (in favor of a higher up shallow bowl shape of new feeder roots - a process that can take a couple of years or more as you only want to take off 1/3 to 1/2 at any time). When you prune branches, try to keep an uneven number as it adds more interest and tension. Cut them back sharply (but above bottom-most growth on each in case they don't bud back well below that). I don't know how brittle or not the branches are in terms of wiring, so if you want to bring them down use little weights instead. Think about having 3 branches at different levels, which will look Oriental and leave room for the flowers and leaves - leaves should reduce somewhat over time, but each early summer try snipping their stems to see if they grow back in smaller (once mature) - just do a few this year in case they don't do well, and never completely defoliate in any one season). Always make sure you're growing it in a mix with lots of grit and some perlite for fast drainage, and stay away from peaty potting soil that stays soggy and compacts in time.

Hi
Have tried to dwarf several DR which is commonly used as a yard plant here. Worlds most elegant tree without a doubt
but real washout as a dwarf lol.
First it is a LARGE tree 40x50 easily . Second if not allowed to gain size will not develop the elegant bearing
IME will not flower under 10 feet at all.
All the characteristics that make it so beautiful are lost.
I gave up on them but still have a very rare white form
that I can't bear to part with. lol
IME you have much better luck with some of the relatives
Jacaranda or Colvillea. much more ammendable to severe pruning but I suspect not under 10 feet.
gary

I live in the central part of Mexico (Queretaro) and there are a lot of Delonix Regia here that grow in parks. I've seen a lot of them with just 5 feet tall with lots and lots of flowers, so I really think they can be made as a bonsai, but the fact if the flower or not will depend on the weather, it is very hot here during spring/summer and not so cold in winter (10 Deg Celsius at the lowest). Take a look at the attached URL.

Scroll down... you will see it

Here is a link that might be useful: Bonsai Delonix Regia

My experience with Bonsai who have a tendency to grow stiff,unbranching is too...wait many years. Sooner or later they will start to show the adult form branching. Just keep topping,don't worry if it replaces a single stem with another single stem,keep topping,wait it out. If the tree is healthy dont give up! one year you will see the change..Time is the remedy.

During my holiday to Tenerife September 2007 in take seed to home that i had found nearly hotel of a Phoenix canariensis and unknown palm tree in the garden of H10 Las Palmeras Hotel in Playa de las Americas. I buy seed of Flamboyant tree in *Villa Las Flores* I grow Delonix Regia in a container, It survive indoors durning winter in Netherlands, some of plants in their second or third year survive indoors. http://hi.baidu.com/jer0enr0land/album/item/2acc91fd48af9eaffd037ff7.html

I've kept one alive out of two through winter in Canada indoors in a a 10 inch pot. One died. The other I moved until I found it's happy spot. It Lost all it's leaves but kept the top few sets. The tree kept growing and dropping it's leaves at an equal rate until spring. I will most likely cut it back soon now that it's branching everywhere that it lost leaves during the winter.

Hello, I bought some delonix seeds 2 weeks ago and soaked them in warm water 24 hours. Those that didn't swell I returned to fresh hot water.
The outer skin started to peel and I also scarified those.
One seed in particular had a bump on it so I planted it into a pot of normal seed compost on a heat mat. Being impatient after a few days I got it out of the compost and found it had a very long root but no cotyledons which seemed to be trapped in the shell. The outer skin had also gone mouldy. In a panic I peeled with some difficulty the skin off and found a strange inner plastic looking skin which I also peeled to reveal the cotyledons.
I have replanted the whole thing and await with baited breath. I then "skinned" the rest which also had mould on the outer skin and have planted those.
I have no idea what to do should they sprout because here in the U.K. the weather is not suitable for some tropicals but I have enjoyed the challenge!