Mark A. Miller
Plant Common Name
There are about 20 to 30 species that make up genus Agastache, which is part of the mint family (Lamiaceae). Commonly called hyssops, they have been long grown in floral beds and herb gardens and are admired for their beautiful summer flowers as well as their pungent, fragrant stems and leaves. All of these herbaceous perennials are native to North America with the exception of one species found in eastern Asia. Most are short-lived, existing in the garden for only three or four years before dying.
These bushy, upright, herbaceous plants are wonderfully fragrant and have square stems lined with pairs of opposite leaves, characteristics typical of mints. The aromatic leaves are sometimes hairy with toothed margins and are held on distinct leaf stems (petioles). The tubular, two-lipped flowers are summer blooming and borne in whorls on spikes at the end of the branches. Flower colors including white, lavender, red, orange, pink and apricot. The fragrant blooms may be attractive to bees, hummingbirds and butterflies. Small nutlet fruits filled with a few seeds follow the flowers.
There are several species and cultivated varieties popular in modern gardens. Anise hyssop (Agastache foeniculum) is a tough perennial native to the northern United States and Canada. It grows well in most sunny, well-drained gardens. The hybrid hyssop, ‘Black Adder’, is a tall, bushy, herbaceous perennial that produces long spikes of dark purple flower buds that open to powdery violet-blue. The two southwestern species, orange hyssop (Agastache aurantiaca) and sunset hyssop (Agastache rupestris), are drought tolerant, colorful and highly fragrant. Their tubular orange and mauve flowers are hummingbird favorites.
Hardiness and culture depend on the species, but most hyssops prefer sunny sites and average garden soil with excellent drainage. Once established, they are often drought tolerant, though regular watering will encourage better growth and flowering. Eastern species should be deadheaded to promote additional flowering later in the season. Some species readily self-sow around the garden.
Hyssops are excellent choices for sunny mixed borders, wildflower plantings and herb gardens.