According to Richard F. Dufresne, Salvia mexicana `Limelight’ may grow to 4 feet in full sun, with 18" spikes. He gives the hardiness zone as "8 (7?)".
Name: Derbeh Mar Vista (Zone 10b) Inherited my love of plants and gar
From a one gallon plant purchased and planted in July, 2015, my Limelight, when it bloomed in November, was six feet high by six feet wide. An amazing plant, and it is coming back gangbusters this spring!