Verbena bonariensis

By Sharleen Pratt, Master Gardener

Verbena bonariensis Courtesy of pixabay.com

I was very intrigued by the plant known as Verbena bonariensis.  This particular Verbena is often shown growing in gardens on the British show Gardener’s World.

I managed to find seeds this spring from William Dam Seeds Ltd.  The package instructed me to start seeds 8 to 10 weeks before the last frost, however, due to a huge demand for seeds the past few years, my package arrived quite late and I was unable to start the seeds until well into April.  At the best of times, Verbena can be an erratic germinator and I was only successful getting one seed to germinate.  However, this one plant was a huge success and I will definitely be trying again next year, although I may be lucky to find some seedlings in my garden.

This plant is one of about 250 species in the genus Verbena. Most are not in cultivation.  It is native to Brazil and Argentina.  Bonariensis means ‘from Buenos Aires, Argentina’.  ‘Buenos’ means ‘good’ and ‘aires’ means ‘air’. It is a perennial in zones 7 to 11, therefore, is grown as an annual in the Peterborough region.  In some milder climates such as California, it can be considered a weed. Verbena bonariensis, also known as Tall Verbena or Brazilian Verbena has stiff upright branching stems.  It reaches a height of 3 to 6 feet and spreads 1 to 3 feet and is unlikely to fall over.  The stiff square and rough stems hold clusters of lilac-purple flowers from early summer right through to late fall.  The deep green, lance-shaped serrated leaves form a mounded rosette at the base of the plant.  The flowers are borne in rounded clusters 2 to 3 inches across.  The cut flowers last a long time in flower arrangements.  England’s Royal Horticultural Society Floral Committee awarded V. bonariensis an Award of Garden Merit (the Society’s symbol of excellence given to plants of outstanding garden value) “because of its attractive flowers and uncluttered habit.” They can make an unforgettable display and although they are tall plants, they have an open and airy appearance which lends them to being tucked in between other plants or even creating a dramatic appearance at the front of a border.  They sway in the breeze and are very attractive to butterflies, bees and other insects.  They prefer full sun to part shade in well-drained soil.

Our very hot summer did not affect its performance and knowing that they are drought tolerant once established is another plus for this plant. There are little known pests or diseases, although powdery mildew can sometimes be a problem.  White spots on the leaves do not seem to have much impact on blooming.

If you leave the flowers to develop seed heads for the birds, the plant may self-seed the following year.  As this was my first season with this plant, I will have to wait until the spring to see if my conditions are good for self-seeding.  I understand that they may not appear until late spring.

It is also possible to cultivate through cuttings and you can find out how to do this in this short video by the very well-known British gardener Monty Don.

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