As the heat intensifies many of the frost-tender species that where planted out in late May are reaching their full glory. A great example of such a species is Verbena rigida which, in early summer, produces short straight stems with bristly leaves and small heads of rich, dark purple flowers. This verbena slowly spreads and intermingles with other plants, where it forms small drifts - it can be used to great effect amongst other herbaceous perennials or in containers.
At RHS Garden Hyde Hall you can find this lovely verbena in the Herbaceous Border where it blends in brilliantly with the purple colour scheme and in the Dry Garden where it survives the heat and low rainfall.
- Common name
- Slender vervain
- Height & spread
- 45-60cm (18-24in) x 40cm (16in)
- Tuberous perennial
- Moist but well-drained, moderately fertile soil
- Full sun
- Frost hardy to -5oC (23oF)
Verbena is a genus of about 250 species of annuals, perennials and subshrubs mostly growing in open woodland, prairies, wasteland and roadsides in North, Central and South America.
Verbenas are long flowering, but very few are fully hardy. They are grown for their flowers which are bright and showy.
This species comes from southern Brazil and Argentina. It makes a lovely garden plant with its upright spikes of fragrant bright purple or magenta flowers that appear in summer. On average it grows to about 60cm (2ft), with rough, stalkless oblong leaves.
As a half-hardy perennial this plant is ideal for providing late summer colour at a medium height in formal and informal garden settings.
- Grow in moist but well-drained. moderately fertile soil in full sun.
- Areas that are prone to extended frosts should be mulched in winter for protection.
- Slugs, aphids, thrips and leafhoppers may be a problem.
- Sow seed in autumn or early spring. Alternatively, take stem-tip cuttings in late summer.
- Divide perennials in spring.
The RHS Herbaceous Plant Committee awarded Verbena rigida an Award of Garden Merit in 1993 and reconfirmed it after another trial in 2001.