Verbena bonariensis

Verbena bonariensis is a very useful plant. This long flowering beauty flaunts its sprays of fragrant flowers from mid to late summer with airy purple flowers on tall, slim delicate stalks that dance in the wind.
The tall, narrow stems provide useful height in an herbaceous border; it is particularly effective if grown in a mass. The plant has an airy, see through look to it, so it can be put in the foreground of a border despite its height.

Verbena bonariensis can be planted alongside a variety of different perennials, including grasses. It works well in a number of garden settings, such as cottage and contemporary gardens. Try it in tropical plant schemes alongside cannas, bananas, ginger lilies and bamboos. It is a graceful counterpart to larger flowers and invariably compliments the landscape without overwhelming any of it.

Brazilian verbena is a superb butterfly plant, rivalling even buddleja and is a sight to behold when the butterflies are fluttering gleefully about it. It makes an excellent cut flower and will flower the same year from an early sowing. This Verbena has a quiet, modest charm that is forever appealing.

• Awarded the RHS Award of Garden Merit
  It has been awarded the Royal Horticultural Society’s Award of Garden Merit (AGM).

Timing:
Verbena is perennial in frost-free growing conditions, but is often grown as an annual and discarded at the end of the flowering season. It can be sown directly, but results are far greater if the seeds are given favourable conditions during raising. Sow early spring for flowers the same year. Sowing to flowering approx 16 to 20 weeks.

Sowing:
Sow seed at 18 to 21°C (64 to 70°F) in autumn or early spring.
Pre-treatment. Seeds will germinate quicker if they are given a period of cold before planting (to mimic spring like temperatures). There are two methods - either place the seeds with a little moistened compost in a plastic bag and place in the fridge for two weeks, then sow as usual. Otherwise, sow then place the entire tray in the fridge.
Sow very finely onto the surface of pots containing moist seed compost. “Just cover” with a sprinkling of sieved soil (1/16th in) and cover the container with dark paper or similar as the seeds need the dark to germinate. Place the container in a dark place. Maintain an optimum temperature of 15 to 18°C (60 to 65°F)
Keep moist, watering from the base of the container but do not saturate the compost.
Germination is erratic, usually around 14 to 28 days, but may take up to 90 days to finish germinating (especially if seeds haven’t experienced cold stratification). Remove the cover once they begin to germinate to allow air to circulate (otherwise they may suffer from damping off) and reduce the temperature to around 15°C (60°F), keep in light but not strong sunlight, a warm kitchen windowsill is often sufficient.

Transplanting:
Thin (prick out) seeds as they become large enough to handle, leaving the seed trays in tact for other seedlings that may germinate later. Use 7cm (3in) pots containing well drained compost mix. You can add 10 to 15% horticultural sand (that doesn’t contain salt) to a regular compost to achieve this.
Harden off young plants gradually for 10 to 15 days before planting out, Pinch back when first planting to encourage branching. Plant 60cm (24in) apart in a sunny position in ordinary garden soil. (Verbena is susceptible to the fungus mildew if planted in a wet, shady locale.) In very poor soils it is worth incorporating some organic matter into the soil before planting.

Cultivation:
Water deeply to encourage roots to grow deeply, resulting in a healthier, more drought tolerant plant. Avoid overhead watering if possible. Where the plant is grown in partial shade the stems may need to be supported, if this is necessary use natural materials such as brushwood or twiggy pea-sticks. Remove the faded flowers for a better following flowering.
Verbena bonariensis can suffer dieback if cut back in autumn, so it's best to leave the plant until spring and cut back the old growth when you see the new shoots emerging at the base. Because it is borderline hardy, plants may be damaged by severe winter frosts. In winter mulch around the base of the plant with a deep, dry mulch to help protect the plant.
It is a short-lived perennial that self-seeds; the resulting seedlings are stronger and more drought-tolerant than those that are transplanted. Any plants lost to frost are normally replaced by their offspring. Its habit of growth is such that it can grow almost anywhere without really interfering with existing plantings and planting schemes.
They prefer dry, light and airy cultivation. Give the plants space and transplant any self sown seedlings that are growing near to each other.
Verbenas do not require a particularly rich soil or fertiliser but will benefit from a light feed in spring.

Plant Uses:  
Wildlife, Bee and Butterfly gardens. First year flowering, Cut flower. Low-maintenance gardens and herbaceous borders. Cottage and contemporary garden schemes.

Cut Flowers:
Cut flower stems can be harvested, when the small flowers outside are just open. Vase life: 8-10 days. Cold storage is possible.

Wildlife:
Verbena bonariensis is beneficial for attracting wildlife, particularly butterflies. It attracts: Brown Argus, Comma, Essex Skipper, Green-veined White, Large White, Meadow Brown, Painted Lady, Peacock, Red Admiral, Small Copper, Small Tortoiseshell, Small White and Hummingbird Hawk-moths.

Origin:
Verbena bonariensis is native to South America where it grows throughout most of the warm regions, from Colombia and Brazil to Argentina and Chile. It is said to have been brought to England from Patagonia in 1834. The genus Verbena contains well over 250 species plus many garden hybrids.

Nomenclature:
The genus name comes from the Latin Verbena, a classical name for certain sacred branches, probably of Verbena officinalis of Europe. The species, bonariensis was named for the city of Buenos Aires, in South America where it was first discovered.
Sometimes, the common name 'Brazilian Verbena' or 'Brazilian Vervain' is found for this species. However, this is misleading and the result of a mix-up with V. brasiliensis, the 'true' Brazilian Verbena, which has been erroneously referred to as V. bonariaensis by several botanists.
Verbena bonariensis is member of a genus of perennial herbs which are sometimes known by the ancient name Vervain which is thought to be derived from the Celtic words fer, meaning 'to remove' and faen, meaning stone, referring to its use in treating bladder stones.
It has the common names of Argentinian Vervain and South American Vervain which reflect the origin of this plant.