Fragrant, trumpet-shaped summer flowers open in late afternoon, hence the common name four o'clock. Frosts kill these bushy plants to the ground, but in mild-winter areas they'll resprout from large, tuberous roots the following spring. Sow seeds in fall or spring; plants also self-sow freely. Treat as annuals in the Upper South.
M. jalapa. FOUR O'CLOCK, MARVEL OF PERU. From Peru. Erect, many-branched shrub forms a mounding clump 34 ft. high and wide. Deep green, oval, 2- to 6-in.-long leaves; sweet-scented, 1- to 2-in. flowers in white, red, yellow, magenta, and many intermediate shades. The hard black seeds are often exchanged by gardeners seeking particular flower colors. 'Broken Colors' bears streaked and freckled blossoms of raspberry-red, orange, lemon-yellow, and white, all on a single plant. 'Limelight' has bright green foliage topped with magenta flowers. 'Salmon Sunset' is soft orange with a pink star, and the Marbles series features color variegation in the blooms. 'Baywatch' is a giant, reaching 69 ft. tall, with large blooms in palest yellow. Regular water.
M. longiflora. SWEET FOUR O'CLOCK. Native to western Texas, Arizona, and Mexico. Grows 3 ft. tall and wide. Medium green, oval, pointed leaves are about 2 in. long. Blossoms are very slender, 4- to 6-in.-long tubes that flare open at the end; they are white flushed with rose or violet and have prominent magenta stamens. The fragrance is particularly sweet, excellent for the night garden.
M. multiflora. DESERT FOUR O'CLOCK. Native to the southwestern U.S. Forms a bushy mound 13 ft. high and 35 ft. wide. Gray-green, roundish to heart-shaped leaves to 3 in. long. Rose-pink or magenta, 2-in.-long flowers have a musky, sweet scent.