It is considered a perennial in southern zones, 10 and 11. In colder areas of the country it's often treated as an annual and discarded at the end of the season and purchased anew the next year. If grown in ground, you might be able to mulch it heavily in hopes of keeping it alive but if growing in a container, it can be overwintered indoors. It can also be propagated by seeds or taking stem cuttings to root for new plants.