Lavender Hyssop (Agastache foeniculum), also known as Giant Blue Hyssop or Anise Hyssop, is an upright, clump-forming perennial of the mint family . It is typically found in prairies, dry upland forested areas, plains and fields. It grows to 2-4 feet tall. It is noted for its mid- to late summer bloom of lavender to purple flowers in terminal spikes and its anise-scented foliage. Square stems are clad with ovate to broad-lanceolate dull green leaves (to 4 inches long) with toothed margins. Flowers appear in many-flowered verticillasters (false whorls) which are densely packed into showy, cylindrical, terminal flower spikes (3-6 inches long). Gaps sometimes appear along the flower spike. Individual, tiny, tubular, two-lipped flowers (each to 1/3-inch long). The flowers bloom in scattered locations along the spikes for about 1-2 months from mid- to late summer. The flowers have no floral scent but the leaves have a licorice-like fragrance. During this time, calyx of each flower remains somewhat colorful. The flowers are replaced by nutlets that are oval-shaped and smooth. The root system produces a taproot.
Typical habitats include openings in dry upland forests, upland areas of prairies, scrubby barrens, and thickets.
Members of the mint family tend to be highly attractive to bees, and lavender hyssop is no exception – in fact, it happens to be one of the most attractive plants for bees and supports a diversity of pollinators. Historically, mass plantings of lavenderhyssop were established in parts of the Midwest and Canada specifically as a “honey plant” to support apiaries. While bees probe the deep tubular flowers for nectar, skippers, fritillaries, and the occasional hummingbird may also visit the plant.
Easily grown in average, dry to medium moisture, well-drained soils in full sun to part shade. Best grown in full sun. Performs well in moist soils, but good soil drainage is essential. Plants tolerate dry soils, particularly once established. Deadhead spent flowers to promote additional bloom. Plants will spread by rhizomes and will easily self-seed in optimum growing conditions.