Verbena hastata

Verbena hastata, also known as Blue Vervain, is a large, hardy perennial that should be planted without hesitation. It stands out with its exceptionally long flowering period, upright and finely branched floral spikes densely covered with small purple flowers. Pollinators flock to it from dawn onwards. The foliage is bright green, composed of elongated and toothed leaves. This plant has something enchanting about it, combining abundant flowering, graphic appeal, and ease of cultivation. It thrives anywhere, in any ordinary, well-drained soil, whether moist, damp or occasionally dry, in the sun, and readily self-seeds in the garden.

Native to Canada and the United States, the Blue Vervain belongs to the Verbenaceae family. It colonises damp soils, riverbanks, wet meadows, and floodplains in its natural habitat. Depending on soil moisture, it can reach a height of 60 to 100 cm (24 to 39in), with a width of 50 to 60 cm (20 to 24in). It grows from a fibrous and rhizomatous stump, forming an erect, relatively narrow clump composed of occasionally branched quadrangular stems. The leaves are opposite, 10 to 13 cm (4 to 5in) long, 2.5 cm (1in) wide, lanceolate, veined, coarsely toothed, and bright green. From June to September, the stems branch out at their upper end and give rise to thin, pointed spike inflorescences, 10 to 15 cm (4 to 6in) long, composed of numerous red buds that develop into small purple flowers with five 5 mm (0.2 in) petals, resembling lilac. The buds, flowers, and bracts create a striking and splendid contrast. The flowers open from the bottom to the top. The flowering period is followed by the formation of small, hard, elongated fruits that contain seeds, which easily self-seed. Small colonies of plants, identical to the parent plant, are produced from the rhizomes.

Still relatively underused in our gardens, Verbena hastata is easy to grow, valuable for adding verticality to perennial borders, and delightful in country-style compositions. This plant stands out at the edge of a water feature, in a damp soil, as long as it is planted en masse. In a slightly wild scene, it emerges effortlessly from tousled or well-organized clumps of gauras and grasses (small Miscanthus, Eragrostis, Stipa). Paradoxically, it also performs well in drier soil, although it will remain smaller. Its delicate, highly graphic spikes contrast with the roundness of roses, complement lavender of the same hue, and its purple stems beautifully accompany the grey or silver foliage of Artemisias, the blond or metallic blue culms of Elymus magellanicus, or the rust colour of Carex buchananii.  Verbena hastata can also be used to prepare herbal teas. The ancients attributed aphrodisiac properties to it!