The oft-misspelled Salvia guaranitica (a search for Salvia guarantica – note the absent “i”) is native to South America. This cultivar, 'Black and Blue', was selected for its nearly-black stems and calyces. Known commonly as blue anise-sage or sapphire sage, Salvia guaranitica is a popular and striking plant in gardens. Paghat has an as-always excellent article about Salvia guaranitica where you can learn more about this plant if you find yourself considering it for your garden.
I should mention that the orange in the background of today's photograph is from Kniphofia triangularis, another eye-catching ornamental.
Photography resource link: for inspiration, the photography of Robert Glenn Ketchum.