If you are able to pot it up in a big tub, and trim some of the oldest roots off, it could last a year or two--assuming you kept it from serious frost! Balled and burlapped, maybe a couple of months. Just laying on the ground, maybe 2-3 weeks though it would probably be looking pretty sorry by the end.

Thank you for replying- escpecially so late!
Don't think I made myself very clear (prob half asleep ;-) but I've put it in the ground where I would leave it if it lived...........I think the main things that worry me are that 1. I was expecting a massive root ball and it was only about the size of a football and 2. I also have its 7ft brother to consider. He could go back in the ground at the other end of the garden too if he would make it. What do you think, worth a try?!

Your question made me laugh - "how long have you got?"

This is only a guess, but I'd say it's worth a try, but would be better if you could leave it til the spring. I'd think that the one you moved will be extra vulnerable to the cold this winter because it's just been moved.

Really thorough watering is very important for transplanted shrubs and trees. You need to get the water in deep where the roots are.

Thank you Beattie. Unfortunately I don't have until spring, I have about 3 weeks to decide 'do or die' literally! I will continue to chuck a 7 litre bucket of water at it every day and cross my fingers. How should I protect from cold as its so big? So far I never have, Its previous location was in a small bed under membrane and about an inch of gravel and I now wonder if that protected the roots from frost and I ought to try and fashion something similar for it in its new place this year?

If it's got to be moved whatever happens, I think you should replant it and hope. The fact that it's 7 feet tall means that the top growth hasn't been killed by frost, or at least not for the several years it would take to get to that height. So the membrane, gravel etc on the ground have not affected its survival either way, so far.

What have you got to lose? Dit it up and replant it and hope that the long range forecast for this winter is wrong (as it normally is) and that we only have a mild winter.

I find they are not very easy to kill off. Mostly you loose the greens and some stem.
One in the memorial gardens lost everything to ground level last winter. We sawed off all of its trunks to 18 inches and left it.
Now it has regrown green on all the trunks.

Unlike woody plants, things like Cordylines don't have to have a big root ball when they are dug up, but it helps reduce the shock. Shock in semi-succulent plants like that is a slow motion sort of thing, though. I would at least prune off about 1/3 of the leaves, starting with the oldest ones, to slow the processeven more.