West Texas cobalt sage is a marvelously distinct species that can be enjoyed by gardeners farther north, as long as they purchase the west Texas form, which is quite cold-hardy. This salvia has rigid stems with narrow, pungent leaves and resembles a bright green, upright grass for much of the growing season. In early fall, cobalt blue flowers burst open almost overnight and are a big draw for hummingbirds. Thanks to its deep roots, this wildflower is extremely xeric. West Texas cobalt sage grows to 4 feet tall.