This spring, the National Garden Bureau announced that 2022 would be the Year of the Verbena. Their idea was clearly to present the annual verbena, the one that we grow in our hanging baskets and decorative containers. However, it made me want to tell you about one of my favorite verbenas, blue verbena.
A Native Plant With Ornamental Qualities
Yes, blue verbena (Verbena hastata) is a widely distributed North American perennial. Also called American verbena or swamp verbena, its distribution extends from southern Canada to Florida and New Mexico. It’s found in damp ditches and on grassy banks where it forms small colonies. Well, usually. Because it’s also found on the edge of rocky slopes and in drier soils.
It’s an upright grower and can reach up to 6 feet (180 cm) in height, although it generally remains more in the 3 to 4 feet (75 to 120 cm) range. The leaves, rather slender and with a rough texture, are sometimes used in traditional medicines (but don’t confuse this plant with common verbena, V. officinalis, the usual medicinal verbena).
Blue verbena has all the qualities you’d want in an ornamental plant. For example, it fits perfectly in the background of a perennial bed. Plus, the plant is sturdy and the foliage remains beautiful all season round. But what about the flowers?
Unique Bloom
Of course, it’s blue verbena’s blooming habit that charms me the most. Between July and September, the plant produces multiple clusters of upright spikes. Starting from the bottom and moving up, the small violet-blue flowers pop open one after the other like popcorn, rarely more than six or seven blooms per spike at a time. I find this gives it a certain humility. I mean, this plant is miles away from a big fluffy peony! Its constant yet modest flowering impregnates blue verbena with a sense of delicacy.
The flowers are visited by numerous pollinating insects and butterflies. And beekeepers consider it to be an excellent flower for honey production.
Naturalize It… Massively!
I consider this plant to be the queen of the naturalized prairie. It blends perfectly with other wild flowers such as swamp asters (Symphyotrichum puniceum), goldenrods (Solidago spp.), St. John’s worts (Hypericum spp.), white snakeroots (Ageratina altissima) and mulleins (Verbascum thapsus). It’s also ideal for revitalizing shorelines, pollinator gardens and revegetating ditches. And it’s deer resistant too!
Blue verbena will develop vigorously in full sun, especially in moist soil, its preferred habitat. That’s where it will best demonstrate its excellent cold hardiness (USDA hardiness zones 2 to 9). However, in the warmer and drier parts of its range, blue verbena tends to behave more like a short-lived perennial or even an annual. Luckily, the plant reseeds itself and can therefore find its own place in the garden over the years.
To avoid what could be a lot of unnecessary weeding, I recommend using it in a naturalized garden rather than in a well-maintained border. That way, you can let it grow where it pleases!
Even though it self-sows, blue verbena is far from being invasive. It just comes up modestly here and there. Looking through other author’s remarks, I found that nobody seems to complain much about it getting out of hand. On the contrary, they often recommend it as a good choice as a remplacement for other invasive plants!