Blue Vervain is a valuable native Canadian species found in moist meadows, wetlands, roadsides and ditches. It produces a colourful show of tubular blue flowers on spikes from mid July through September. Flowers bloom on each spike a few at a time progressing from the bottom up. It is both very fast growing and easily grown from seed. While blue vervain is often included in wetland remediation mixes, it also makes a great addition to the formal perennial border. This tall plant grows from 90-120 cm (3-4′) high, does best in full sun to partial shade and will readily self seed in moist, deep organic soils.
How to Grow
3,500 seeds/gram. When direct sowing outdoors, due to seed dormancy caused by a hard, impermeable seed coat, the seed is best sown in late fall This allows the seed to be naturally stratified over the winter. Indoors, sow seed March 1st in a soil-less mix. Before sowing, nick or file the hard seed coat to improve germination or after sowing seed, water the growing medium and place in a freezer or outside for 4 to 6 weeks. It is best to just press the seed into the growing medium as it needs light to germinate. After cold stratifying, bring the container back to the warmth, place under lights and maintain a temperature within the medium of 20 C (70 F) for the 5-10 day germination period. After germination grow on under lights at a slightly cooler temperature then harden off and transplant outdoors to a sunny spot with moist to wet soil.