Perennial
Purpletop vervain
Verbena bonariensis
A tall, airy herbaceous perennial with slender stems and small purple flower clusters from summer into autumn. It needs full sun and free-draining soil, may be lost in hard winters, and often replaces itself by self-seeding.
- Size
- 1.5–2.5 m high · 0.1–0.5 m wide
- Light
- Full sun
- Water
- Moderate
- Winter
- Needs protection
- Seasonal form
- Dies back
- Maintenance
- Low
Before planting
- Give it full sun and well-drained soil; cold, wet ground in winter is a greater risk than a dry, open site.
- Allow for height of up to about 2.5 m while keeping the planting visually light and narrow.
Why choose it
- Small purple flower clusters float above neighbouring plants on tall slender stems.
- The long flowering period is valuable in prairie-style and pollinator-friendly planting.
Care
- Cut old stems down in spring as new basal growth appears.
- In cold areas, use a dry winter mulch. Leave some seed heads for self-seeding, or remove them before seed ripens to limit unwanted seedlings.
Good to know
- Individual plants can be short-lived after hard frost, but self-sown seedlings often maintain the display.