Hi, welcome to GoY, look at the size of the root ball, you need to put it in a container which is at least 2" wider, to give you 1" more all round the root ball, you could increase this, but not more than 2" more room all round, Derek.

Thank you.

Thank you.
I did this and noticed it was infested with ants carrying little white sacks! I inquired at the garden centre who advised me to put a solution of liquid nipon unfortunately within a week my Cordyline looks like it’s dying, it looks very sad and leaves are turning yellow waiting to fall off. I have fed it since but it still looks very unhappy.
Can you help please?

Hi, firstly, ants don't like damp places, so it sounds as though the compost was too dry, secondly, did you put the liquid nippon straight onto the pot ?, I think with this, you put a few drops near the ant run, as a bait, so that the worker ants take it into the nest which kills the rest of them, if you put it directly on the compost I think it will have killed the plant, or at least tried to, I think all you can do now is take it out of the pot, check for any remaining ants, I doubt you will find any, but it's always best to check, scrape the stem with your finger nail in several places along the stem, to see if there's any green, [this may be quite difficult on a Cordyline], if there's no green, just brown dead stem, I'm afraid it's dead, and there's nothing you can do, if there is some green, I would remove as much soil as possible from the rootball, use a hosepipe if necessary, and repot into fresh compost, and wait to see if there's any response, which could take up to a year, if nothing has happened by this time next year, I would get rid of it, good luck, Derek.