Four o'clocks are tuberous, tender perennials with pink, yellow, lavender or white flowers.  The flowers open in the late afternoon, typically around 4 p.m. or so, and then remain open until the next morning. 
Direct sow after frost, or start indoors 6-8 weeks earlier, pressing lightly into the soil since they need light to germinate.  Tubers may be dug and stored over winter.  Will self-seed.