Any tree that size would need a HUGE pot. You could prune back a Eucalyptus, I suppose, but I'd be unhappy about keeping one in a pot permanently as I can't see it thriving. The trouble with any tree is keeping it to 5m. of course, and my feeling is that the size you want is too big for a pot.

Is there any mileage in erecting a trellis and growing something evergreen on it? I realise that you can't go to 5m, but it would at least help.

Agree with Spritz - whatever you grow in a pot will not attain the height you want. Eucalyptus, even if its stooled every year, will not be at all happy in a pot - it has a very long main root that goes down a long way, and it won't be able to put that out contained in such a way. The only possible exception is an absolutely enormous pot, such as trees are grown or transported in for exhibition purposes - these are shifted about by crane or fork lift trucks, usually, because they're obviously very heavy - the size of the container can be 5 feet deep by 6 feet wide. Even so, Eucalyptus would not be a good subject.

Hi! Sorry that I never got back to you both to say thanks for the advice.Better late than never! After looking several times back in 2010 and not seeing an answer, I won't bore you with the reasons for not having resolved my dilema, but I only just looked at this site again for a different question and was really interested to see the advice. Ironically I had literally just gone ahead with the pot and eucalyptus idea, but can see that it is probably not going to work. If the tree starts to look sickly I will replant it somewhere else in my huge garden where there is room for the roots. I had already done the trellis with a Rambling Rector rose on it, but still don't get the height. I might look at using some tall grasses/bamboo in the pot instead. Thanks again.

Bamboo is a good idea - The roots would be restrained! I love it anyway - in the winter, it's a joy when it sways about. Good luck, anyway, and I'm glad you came back!