This is a shrubby salvia to 1-1.5 m in height, with large, rich purple flowers and greenish, purple-tinted calyces, from late spring till autumn, so it is good value in the garden. It may need some support from cradle stakes or other plants. It is pretty with pink flowers such as Pentas, roses, or bright pink salvias. It looks good with silver or purple foliage, or with red or orange flowers such as Canna or lion's ear (Leonotis leonurus) for a more vibrant look. It can tolerate some shade. It should be pruned very hard in late winter, and the occasional stray stem can be removed to tidy it during the growing season. Its parents are said to be Salvia guaranitica and Salvia gesneriiflora 'Tequila'.
Postscript: I eventually removed my plant. I had grown it for many years but I got tired of its untidy, sprawling habit. A better-behaved plant is Salvia 'Amistad', which has the same vibrant purple flowers over a much longer time period.