Purpletop vervain

Verbena bonariensis

Description

Purpletop vervain is a short-lived perennial from South America that grows with a highly distinctive upright and open habit. Clusters of light purple flowers occur in late spring on 3-6 ft. tall branches that often ascend above other plants in the garden. This unique perennial grows well throughout the Inland Empire in sunny locations and with low amounts of supplemental water. It is combined with other flowering perennials and butterfly plants in mixed plantings, along borders and in small masses.

Plant Type: Perennial
Foliage Character: Evergreen
Habit: Upright, Open
Growth Rate: Short-lived, Fast
Foliage Color: Medium green
Flower Color: Lavender
Flower Season: Spring
Soil Adaptations: Well-draining soil, Clay
Exposure Adaptations: All day sun, Heat, Frost, Drought, Aridity
Function: Wildlife value, Flowering accent plant, Attracts butterflies, Borders, Banks
Height: 3 ft. – 6 ft.
Width: 3 ft.

Watering Schedule: Low 2

For most situations, we recommend watering deeply every 2 weeks after establishment.

Learn how to apply this watering schedule to your landscape on our How to water waterwise and California native plants page.

Important Notes

These are general guidelines. Always observe and adjust as necessary for your landscape.
If it rains over 1” you will likely not need to water for at least another two weeks. Before watering again, check the soil. It should be significantly dry at least 4” below the soil surface before watering.
To save water, in many cases you can go longer in between waterings during the winter, often up to 3-4 weeks between watering for well-established plants. Two weeks after watering, check the soil approximately 4” below the surface. If it is still significantly moist, you can wait longer before watering again.
In most cases, if you have a “smart timer” or weather sensitive irrigation controller, you may use these features to save some water in in the fall and winter. If you are using automatic weather adjusting functions, continue to allow the timer to run every two weeks. It will adjust the number of minutes it runs to account for the cooler weather.
It is important to group plants with the same water needs together in the landscape to avoid needing to over or under water plants when running your irrigation system.

Prune out spent flower stalks or leave them on to develop mature seeds if you want Verbena bonariensis to lightly seed itself around the garden. After blooming, plants flower stalks along with leaves will eventually begin to look leggy and ragged. When this happens, cut almost all the way to the ground, leaving just a few buds at the base of the plant. Plants will grow back reinvigorated. At certain times of the year, these plants often develop a white fungus on the leaves called powdery mildew. In general, there is no need to resort to fungicides, as the plants are simply prone to the infection and can usually survive it with no problems. If the powdery mildew is significant, simply cut back to the base, as explained above, to remove infested parts of the plants and stimulate new growth. It is best to throw out mildew infested material rather than compost it or keep it on site as part of the mulch layer. Good air circulation around plants and keeping foliage dry helps discourage powdery mildew (S). References