In theory, over time, up to 1.5m x 1.5 m. If you can find somewhere it likes to grow, I've never managed to get one to survive, never mind reach that size...

I had one of these for about 15 years or more and it grew to the size Bamboo suggests. It was planted in the most unlikely spot in a tiny patch of soil next to a fence and also by my back door. I loved that shrub more than any other I have had since; the perfume was delicious and although it wasn't tall, it grew in width. I'd read that they can suddenly die for no apparent reason and that's what happened to my beautiful girl. I know that if I planted another I would be so much more careful about planting and probably wouldn't have such a lovely result. Good luck with yours Marian.