Salvia splendens Dark Purple
Some flowers can be just too dark, am thinking of the all black Pansy for example, which can make them difficult to place in a garden. They need a bright companion, as shown here where they are planted with Tithonia 'Fiesta del Sol', to lift the mood from the sombre tone which they evoke.
Silver foliage plants make for a sophisticated match also, so this Salvia could look good surrounded by the old silver dust bush, a Senecio or Cineraria species. Salvia splendens have few pest or disease problems though snails are partial to young seedlings. They tolerate heat and dry well but need regular removal of spent flowers to keep blooming for months.