Verbena hastata Seeds | Blue Vervain
LATIN NAME: Verbena hastata
COMMON NAME: Blue Vervain
Plant Profile
Blue vervain is a tall, upright perennial of wet meadows and riverbanks, with square stems that branch near the top into a candelabra of slender spikes. Plants reach 1-1.5 m in good ground, with opposite, toothed leaves that are rough to the touch, and small blue-violet flowers that open in rings from the bottom of each spike upward, so a single plant stays in flower for six weeks.
The flower spikes are thin and stiff, more architectural than showy, and they hold their shape when cut and dried. In the wild the plant grows in damp grassland, roadside ditches and the edges of ponds, and it will take a season of standing water far better than most perennials.
Verbena hastata is native to North America, from the east coast to the prairies, and it has followed ditches and disturbed ground westward. It is short-lived on dry sites and long-lived on wet ones, and it self-sows freely in bare damp soil.
Science & Biotechnology
The plant’s chemistry is dominated by iridoid glycosides, chiefly verbenalin and hastatoside, together with verbascoside and a small volatile fraction. Verbenalin has been studied for its effect on the nervous system and for anti-inflammatory activity, and the European vervain, Verbena officinalis, has a longer pharmacological record than the American species.
Verbena belongs to a family that also includes lemon verbena and the lantanas, and the family is unusual in accumulating iridoids rather than the alkaloids common in other medicinal groups. That chemistry is why vervain tastes bitter and why it has a long history as a tonic rather than a pleasant tea.
For growers, the useful biology is in the seed. Verbena hastata sets hard-coated seed with a dormancy that requires cold and moisture to break, which is why a spring sowing without stratification often fails while self-sown seedlings appear in autumn.
Uses & Benefits
In a garden the plant earns its place at the edge of a pond or in a rain garden, where its height and vertical flower spikes give structure that moisture-loving perennials often lack. It works at the back of a damp border behind astilbes and ligularias, and the dried stems are useful in winter arrangements.
Bees, small butterflies and hoverflies work the flowers steadily, and the plant is a larval host for several moths. Herbal use centres on the dried flowering tops as a bitter nervine, usually in tincture rather than infusion. Commercially the plant is a minor item, sold mostly to herb growers and to native-seed mixtures for wetland restoration.
Growing from Seed
Sow in autumn and leave the pots outside through winter, or give the seed four to six weeks of cold and damp in the refrigerator before sowing at 18-20°C in spring. Germination is uneven, and a second flush usually appears after another cold spell, so do not discard a flat that looks empty.
Plant out at 45 cm apart in soil that stays moist, in full sun or light shade. Water well through the first season; after that the plant looks after itself in any ground that does not dry out completely. Cut the stems to the base in late winter. Plants are short-lived, so let a few seed heads ripen where self-sowing is welcome.
Our Take
A plant for the wet corner that nothing else will take, tall enough to give the border a vertical line and modest enough not to dominate it. Let one seed head ripen and it will keep the colony going without being asked.
Related Reading
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