Spring's probably best, so that it has a season to establish before the rough weather arrives, but you'd need to ensure its kept well watered throughout the spring and summer for the first year or two.

Bamboo, I have one in a pot which I cloak in fleece in the winter. Do I really need to do this? The tree is about 5 years old.

I note you live in the South - if you're not far from the coast, probably not. Otherwise, if you have it in a southfacing, sheltered position, out of harsh north and east winds, again possibly not - but who knows how it would have coped last winter, so in most winters, I'd say no, but we never know what kind of winter we're going to get. It's not snow so much as cold temperatures which may cause the compost in the pot to freeze, so on balance, I think I'd bubblewrap or fleece the pot to be sure, or at least have it handy in case we get a nasty dose of freezing weather.

Thanks Bamboo. I'm in the Weald, north of the South Downs and about 24 miles from the coast so think I'll continue the wrapping to be on the safe side.