Salvia azurea var.grandiflora
Growing from North Carolina and Tennessee south to Florida and Texas, this is a tall, quite gangly salvia that flowers towards the end of August and September.
It's tendency towards waywardness can be much improved by shearing by half in early June, to promote a tidier look.
Untrimmed it can be trained upwards against a wall or similar.
Needs to be grown in a sheltered, sunny spot with sharp drainage.
Drought tolerant and good for a walled garden.
Photo: Andrey Zharkikh from Salt Lake City, USA, via Wikimedia Commons
Well drained, shelter