I got this plant when it was basically a barely rooted cutting and it was back when my garden had no ground cover so I was just hoying plants in willy nilly, better than weeds was my reasoning.
Please see this photo....
I've had it in the garden for 5 years and cut it back quite a bit each year, it grows over the steps very quickly. For the first time, last year, it flowered. I think it was because we had a really long spell of heat. It had never flowered before and my wife and I were thrilled.
We haven't seen it in any other garden here in SW Scotland.