Salvia uliginosa is a frost hardy clump-forming perennial with mid-green leaves and steel blue flowers which are borne from late summer to mid-autumn. Best planted in moist soil in full sun or passing shade. Some shelter from cold, drying winds is advised.
Don’t be frightened by the suggestion that it grows to 6 feet. The structure of this plant is fine and vertical, and it can be cropped down in early spring, resulting in new stems.
In very cold areas, I would advise that you grow this in a pot, or plant out and bring in over very cold periods, although it does grow outside in many of the Cornish gardens we have visited.
The picture was taken at Picton Castle Gardens in Wales in September, with the plants growing in a border, so it’s fairly hardy! They seem to have put up with severe frost here over the winter.