Polystachya is a Mexican winter flowering salvia growing about 2m high. In Mexico there are quite a lot of colour variations but the usual one in Australia is a smoky blue. It starts to flower late autumn. It has been in Australia for about 25 years, longer than a lot of salvias.
Polystachya will grow in part shade but then the stems can tend to be floppy, sun might be best.
It can be grown from cuttings or seed.
Iodantha is a similar plant but deep magenta colour. Blue Bird is a bit brighter blue if it is in stock