Culture
Best grown in evenly moist, well-drained soils in full sun. Tolerates poor soils as long as drainage is good. Seed may be sown directly in the garden after last frost date. For earlier bloom, start seed indoors 6-8 weeks before last frost date. Set out seedlings or purchased plants after last frost date. Cold hardy in Zone 7 and warmer. Plants may persist in Zone 6 if planted in a protected location and allowed to self-seed. Plants more freely self-seed where reliably hardy and they have escaped gardens and naturalized in a number of areas.
Noteworthy Characteristics
Verbena bonariensis, commonly called Brazilian vervain, is a rapid-growing, clump-forming tender perennial. In St. Louis, plants typically form a 1-foot tall basal clump of serrate, lance-shaped, dark green leaves (to 5” long) from which rise erect, slender, wiry, branching, sparsely-leaved, 4-angled stems to 3.5’ tall bearing clusters (to 2” across) of tiny rose-violet flowers. The flowers are attractive to hummingbirds, butterflies, and other pollinators. Blooms mid summer to fall. Synonymous with V. patagonica.
Genus name comes from a Latin name used for some plants in religious ceremonies and also in medicine.
Specific epithet means of Buenos Aires, Argentina.
'Buenos Aires' features lavender flowers with more distinctly purple coloration compared to the species. Otherwise this cultivar shares all of the physical and growth characteristics of the species.
Problems
No serious insect or disease problems. Watch for powdery mildew.
Uses
Group or mass in mixed borders, meadows, cottage gardens.