Identifying Small Seedlings in the Central Texas Garden:
Verbena bonariensis seedling
Verbena-on-a-Stick, or Purpletop Vervain, (Verbena bonariensis), is a tall and slender-stemmed perennial with rosy-lavender flowers that attracts many insects to the garden. The seedlings from last year's plants grow slowly through the average Central Texas winter and then begin their upwards spread in the spring. Verbena bonariensis can grow from 4 to 6 ft (120 cm) tall and can spread to 3 ft (90 cm) wide. At maturity, it will develop a woody base and in mild climates may last for several years. The fragrant lavender to rose-purple flowers bloom in tight clusters on slender, square stems from mid-summer until fall frost. Leaves are lance-shaped with a toothed margin and are several inches long. It is an excellent plant for dry conditions, once established, and takes little care.
This interesting plant has a main rosette of larger leaves and tall stems carrying fewer, smaller leaves with a main "head" and side shoots with tufts of flowers, very sought after by butterflies and other small pollinating insects. Another good feature of V. bonariensis is that because it is light and airy in looks it may be planted almost anywhere in the flower bed without hindering the view of plants behind it.
The name 'bonariensis' refers to Buenos Aires, Argentina, an area of early collection, but it can be found in many parts of Central and South America, and has escaped cultivation in the Southern United States. Generally the plants thrive in zones 7-11 but can be grown as an annual in colder climates.
Once planted it usually comes back again with no effort on the gardener's part. There will be a modest number of seedlings - a surplus may be disposed of, or transferred to more appropriate places in the garden.
It performs as a tender perennial hardy in USDA Zones 7-11 and can be grown as an annual in areas where it is not winter hardy and will bloom in the first year when grown from seed. The long spaces between nodes give it a sparse appearance but allow it to intermingle and coexist with other plants.
This plant grows best in a well-drained soil. It prefers full sun to partial shade and needs regular moisture to look its very best. V. bonariensis has a reputation of being rarely attacked by insect pests, but is sometimes susceptible to powdery mildew. Verbena-on-a-stick can be propagated from herbaceous stem cuttings. The seeds need no pre-treatment.