They tend to flower in the second half of summer, attracting butterflies and bees. More importantly their flowers are long-lived and durable. Most come from South America and, although they have a short-lived tendency, they often come through harsh winters if given good drainage.
Hardy perennial verbenas
This angular, willowy verbena produces a strong, straight stem topped by a flat head of orange-eyed, purple flowers. These are at their best in August and September, just when the butterflies really need them. The flowers persist, long after the nectar supply has dried up, leaving a dark and dramatic seedhead. In some gardens V. bonariensis (literally verbena from Buenos Aires) seeds down too prolifically, while in others it rarely does.
It is always short-lived, probably lasting about four years, but it can come through a hard winter well as long as the soil is reasonably drained.
Verbena bonariensis is easily grown from packets of seed and, if sown by March, it will flower in the same year. Its willowy straightness provides a strong vertical, so this is one plant that should be used en masse and woven through other perennials. I have seen it grown among the bright-red peony-flowered dahlia the 'Bishop of Llandaff'. The strong stems acted as stakes so that no bamboo canes were needed and they enhanced each other richly (up to 6 ft/2m).
This much shorter verbena reaches roughly a foot in height( 30 cm), but it has much more vibrant flowers held in a candelabra formation. The tiny purple flowers pop up at the end of the branching stems over months and this is often one of the last flowers in the garden in November.
Verbena rigida is also easily grown from seed and generally plants bounce back after a hard winter, although shoots may not reappear until late May. There are lilac forms and 'Polaris' is a pale, almost grey, form.
This taller verbena shares the same candelabra head arrangement as V. rigida, but the flowers are much more tapered and stiffly erect. It reaches four feet in height (1.2 m) on good soil, but it must have good drainage to overwinter. The pink form, 'Rosea', is extremely attractive and it’s often used with prairie planting among echinaceas and grasses. A fine upright seed head follows and eventually (just like V. bonariensis) it turns jet black.
This purple verbena produces slender heads of flowers, rather like a Timothy grass, and purple flowers appear in a ring round each head. It’s willowy and unusual, but very eye catching (90 cm/3 ft).
Tender varieties of verbena
Looking very like a large bedding verbena, this mauve-flowered form was found by gardening journalist Peter Seabrook. Although siad to be hardy, I have lost plants in bad winters. Give it a warm, well-drained position.
A ruby-red. tender verbena that provides a perfect contrast to silvered foliage.
Mid-pink verbena originally from the Kent garden of the same name. Fragrant flowers on a graceful plant.