Plant Spotlight – Verbena bonariensis

Few plants were as fashionable as Verbena bonariensis over the last two decades. As gardeners everywhere grew to appreciate its many good qualities it became the archetypal ‘designer’ plant. And then, in the eyes of many, it was overused; an unforgivable garden cliché.

Overused maybe, but Verbena still possesses all of the good qualities that made it so popular in the first place, good qualities that are no more diminished by familiarity than those of penstemon or foxgloves, or any other often-used garden plant.

In fact, Verbena was prized by prescient gardeners long before it became a universal trend. Beth Chatto describes it in her famous ‘Dry Garden’ in 1978:

“Verbena bonariensis sends up tall (5ft/1.5m) wiry branching stems topped with tufts of mauvish scented flowers. They seed about, so accidentals would probably place themselves ideally among something I have not yet considered.

There are dwarfer ones too, most of them fairly violent shades of purple and magenta. They could look jewel-like in the late summer and autumn, rising among Ballota pseudodictamnus and Jackman’s Blue Rue.”

They are South American and not entirely hardy but this ‘seeding about’ that Chatto describes mean that they usually remain an ever-present in the garden regardless, with young plants emerging all over in spring, even if the original plant succumbs to a particularly cold winter.

Cuttings can be taken too (in late-summer/early autumn), as extra insurance, but are rarely necessary if plants are planted in a suitably free-draining, sunny position in the first place. Besides, nursing cuttings through the winter indoors could be argued to prove no less effort than providing established plants with adequate protection in the first place.

They grow well at Winterbourne, in the Walled Garden and on the Terrace, favouring our dry, free-draining soil and sheltered spots surrounded by warm walls and wind-breaking hedges. So happy are they in certain places, that they have even become somewhat of a menace, seeding themselves where they are not wanted, such as the cracks between paving stones and bricks.

Verbena combine so effortlessly with anything and everything that they can be u

sed almost anywhere providing that the conditions are right. They look great with other airy grasses and perennials that sway in the breeze like the giant oat grass, Stipa gigantea, or cool-blue Russian sage, Perovskia atriplicifolia.

This year we have tried growing them at the centre of big terracotta pots on the Terrace, in combination with daisy-like Osteospermum ‘Tresco Purple’ and neon-pink Salvia ‘Hadspen’. They’re planted around our Dipping Pool too, poking through grey-leaved lavender, and in the Arboretum Lawn Borders with huge ornamental cardoons and giant fennel.

Maintenance is easy, just cut them back when the frosts arrive to about 6 inches above ground level where they’ll reshoot from again the following spring if they survive. If you don’t cut them back, they shoot from much higher up the plant, become top heavy, straggly, and fall over. Much better to start again from the ground-up each year.

Several related species are becoming similarly popular. We’ve successfully grown Verbena rigida for a number of years now. It is much shorter, about 2-foot-tall, and with richer, stronger-purple flowers. Like V. bonariensis it needs to be cut back and allowed to re-shoot from the base, but will only do so if conditions are mild, or it is planted with adequate protection. Extra consideration should be given to the latter – It is even more tender than its better-known cousin.

We’ve also trialled (but much less successfully) the scrambling Verbena tenera ‘Sissinghurst’. A prostrate species, it does well pushing its way through other plants and poking out its bright-pink flowers. But on its own we have found it too sparse in growth and habit to fill containers or large, open spaces, and needs very regular deadheading to promote prolific flowering.

Verbena bonariensis is still the best and most useful species for gardens in our climate, and is far too good to give up on simply because we have come to know it so well. It is so easy to grow and cheap to reproduce from seed, and pollinators love it too. No wonder it became so popular!