Spring is the best time - I'd risk cutting off that long stem now, but then I'm in London, where its much warmer for longer and winters aren't usually as bad. Don't know where you are, so I'll leave it up to you. Olives, by the way, should be in full sun, preferably in a south facing position, just in case yours isn't so placed.

Thanks for the response that's what I was thinking. I'm in leicester so not much further north. The taller stem is growing a lot more dense so once cut off it might encourage the rest to grow.

Thanks again.

I can't help but have the feeling that this tree isn't getting enough sunlight, and that's why its produced a long top leader, in an attempt to get more light. If that's the case, cutting it off won't help enormously.

Secondly Leicester is a way different microclimate than London because London is a heat sink, its so built up. I wouldn't cut one even in London right now if it was in a very open area without much paving round about, but in a built up area in, say, a southfacing garden in front of a warm wall, then yes, I'd risk it.

Hi,First of all well done for putting in an Olive tree,every garden should have one.My son bought my wife one for her 50th, 11 years ago.He bought it home in a pot in the back of his car and as I had a spot in the garden left open when I got rid of my greenhouse, stuck it in there and left it to its own devices.To date I have cut it back twice,the last time about 4 years ago when I reduced it to about a third and looking at it now will give it a good,hard chop next Spring,again reducing it by about a third.I love the silvery foliage all year round and as I have several bird feeders in it, it is ideal for them. If you look at my photos you will see just how big it can grow.Forget about harvesting Olives as you can,t just eat them off of the tree, if that was your intention.I live in Hampshire with a nice,sunny, south facing garden but have seen these growing Abroad in some sparse conditions so hopefully yours will be OK.I personally would leave it alone to become more established,it didn,t do mine any harm, kerryvw.