Brazilian vervain (Verbena bonariensis), also known as purpletop vervain, produces dense clusters of lavender-purple flowers atop slender, 4- to 5-foot-tall stems from early or midsummer to frost. It self-sows freely.
Brazilian vervain tends to be perennial in Zones 6 or 7 to 10; elsewhere, it makes a showy annual. Butterflies love it, and it’s nice as a cut flower too. Best in full sun; it can take a bit of shade but may be somewhat sprawling and prone to mildew if it doesn’t get enough light. Be aware that Brazilian vervain can reseed to the point of becoming aggressive or even invasive in some areas (particularly in Zone 7 and south).
Harvested in fall 2019. At least 50 seeds.