Orange tree.

how long would you give an orange tree to start behaving.

We planted one at least five years ago, possibly seven.
it didn't grow much for ages, then started to grow, and was covered in blossom. Smelt divine. Some of the oranges formed, most dropped off. By the end of two months they had all dropped off.
We thought it might be a bit immature, so gave it another year, same thing happened, and again the next year.
This time it was white with blossom, the wee oranges formed and most fell off, but we had about a dozen that were growing to the size of large marbles. We were getting excited. Then they dropped off, one by one, and now there are none, yet again. It's about two metres tall now, I think it's had it's last chance, we have so little garden that is actually SOIL, that I could well do to utilise that ground better than a recalcitrant orange tree that thinks it's here as an ornament

I had oranges my first year. Not many, but a few. Produced ever since.
They will drop some, all can be a sign of stress. Watered regularly? Feed yearly?

Funny thing about citrus, is that they will drop their fruit like you describe, if they're too wet, OR too dry. they prefer free draining soil with regular watering. Also, you haven't mentioned what you feed it, don't get swayed by the popular 'pee on it' theory, or the old epsom salts one either. Use a specific citrus fertiliser at least 3 times a year (Spring, Summer, Autumn)

It WAS well fertilised with citrus fert, and it WAS watered regularly. The thought occured to me that it may have been too well looked after,

BUT IT IS NO MORE.

We made the decision to take it out, so out it came. Not ten minutes ago.

Now I have somewhere to plant the lillies that came out of the copper and need to be in soil for a season. My opinion entirely.

Thankyou to those who replied. it was disheartening to read of a tree producing frut the year after, and if I remember rightly, we also haqd fruit in the second season, and prolifically after that, in a house where the soil was so good that if you stood still for ten minutes you'd have roots on the bottom of your feet. Maybe our sandyish seaside soil is not suitable for citrus, but the feijoas love it.