Verbena bonariensis

Tall Verbena will grow to be about 24 inches tall at maturity extending to 4 feet tall with the flowers, with a spread of 24 inches. When grown in masses or used as a bedding plant, individual plants should be spaced approximately 18 inches apart. It tends to be leggy, with a typical clearance of 1 foot from the ground, and should be underplanted with lower-growing perennials. Although it's not a true annual, this fast-growing plant can be expected to behave as an annual in our climate if left outdoors over the winter, usually needing replacement the following year. As such, gardeners should take into consideration that it will perform differently than it would in its native habitat.