ID please

Needs to be at the back of the border. It can get rather tall if you let it.

It's the tall plant, left of centre, above the grasses. A very architectural plant.

 

@Snorky85 It's west facing with a 6ft fence behind it (you can just see it). So it doesn't get sun until around lunchtime.

We used to cut some of ours down each year as they grow quite quickly but now we remove about one third of stems per year and cut back anything on the remaining ones that have dead flower heads.

You can just see it in this picture in October 2017 when it was in its first year in the ground. Mrs Shiney did it from cuttings and was probably in its pot for two years. The ground there has lots of garden compost and horse manure. Some others that we have in the garden don't grow as vigorously as they're in shady areas with poorer soil - but they still grow happily, but thinner, to 6ft.

 

It will go nicely in your garden and you can keep it under control if it's getting too big.

 

The golden leafed variety looks quite impressive as well. We have found that it tends to grow more compact and the flowers not quite as big - but a good contrast.

 

Very nice. Once settled in it should grow quickly.

Even when pruned they still come back well. We removed one third of the stems from this one in the Spring and it's growing like mad.