Blue vervain (Verbena hastata) is an upright biennial. This wildflower grows 3 to 5 feet tall and spreads 2 to 5 feet wide. The reddish-green stems have flat sides and are covered with fine hairs. The green leaves have toothed edges. Five-inch flower spikes are covered with violet flowers in June to September. This long blooming wildflower is found growing wild in prairies, meadows, soggy thickets, marshes, ditches, fence rows and pastures. Blue vervain attracts butterflies to your flower garden. This flower thrives in USDA plant hardiness zones 3 to 7.
Remove grass, weeds, shrubs and debris from a planting area with full to partial sun exposure. This reduces the competition from other plants for soil nutrients and water.
Loosen the soil by turning it over with a shovel. Spread a 2- to 4-inch layer of compost over the soil. Work this into the soil and break up any dirt clods with a garden hoe. Rake the soil smooth and level.
Dig a hole deep enough to hold the blue vervain rootball. Remove the blue vervain plant from its container and place it in the hole.
Fill the hole with soil and gently firm it down around the blue vervain plant. Plant the rest of the blue vervain plants 12 inches apart.
Pinch the stem tips back to encourage the growth of more branches for denser, fuller plants. Sprinkle the area with water until the soil is wet.