mamosa

You can selectively prune out branches but like all shrubby members of the pea family, don't do all the stems as they often won't sprout back from bare heavy wood/branches.

Incidentally, do you know which exact species of Mimosa (Acacia) you have?

I will have to check with my wife as to the exact species.I will get back to you . thanks for your reply

I really wanted to stop it growing any taller and thought it would be best to pinch out the top.Could this be the answer?

Yes, just keep pinching the top out.

trhank you for quick reply.I will pinchout the top. It is growing really strong so we are hoping for some flowers next year.Thank you once again