Hummingbird Mint is a popular garden plant, celebrated for attracting pollinators and for its aromatic foliage. The common name covers numerous species within the genus Agastache, a member of the mint family (Lamiaceae). Determining if it is a perennial depends on the specific species or cultivar and the local climate. Agastache includes plants ranging from true herbaceous perennials to those often treated as annuals in colder regions.
The Zone-Dependent Perennial Nature of Agastache
The perennial status of Agastache depends almost entirely on the winter temperatures of its environment, defined by the USDA Hardiness Zone system. Many varieties are reliably perennial in zones 6 or 7 and warmer, where winter temperatures do not kill the root crown. For example, Agastache rupestris (Sunset Hyssop) is generally hardy in zones 5 through 9, while Agastache foeniculum (Anise Hyssop) can survive in zones as low as 4 to 8.
In colder zones, generally 5 and below, most Hummingbird Mints are classified as tender or short-lived perennials. These plants may survive a mild winter, but they often die back completely when the ground freezes deeply or stays wet for too long. Even in borderline zones, survival is not guaranteed, as the plant needs to enter a successful period of winter dormancy.
Optimal Growing Conditions for Longevity
To maximize the chance of Hummingbird Mint surviving the winter, especially in colder or wetter regions, specific growing conditions are necessary. Agastache species thrive in full sun, requiring at least six hours of direct sunlight daily for optimal growth and flowering. This light exposure also helps to dry the soil quickly, which is a major factor in winter survival.
The most critical requirement is well-drained soil, as wet winter conditions are a primary cause of root and crown rot. The plant prefers sandy or rocky soil that is lean and infertile, and it will struggle in heavy clay or overly rich, water-retentive soils. In regions with cold, wet winters, planting in a raised bed or on a slope can provide the necessary drainage. Leaving the spent flower stalks intact over the winter is also recommended, as the remaining stems can protect the plant’s crown from harsh weather.
Ensuring Return Through Propagation and Self-Seeding
Gardeners can ensure a steady supply of Hummingbird Mint year after year. Many Agastache varieties are prolific self-seeders, dropping seeds that will germinate and grow into new plants the following spring. Allowing the flower heads to mature and drop their seeds in the fall is a simple way to maintain a population, effectively treating the plant as a reseeding annual in cold climates.
For maintaining specific cultivars, division is a viable method of propagation. Clump-forming varieties can be dug up and separated every three to five years to rejuvenate them and create new plants. Taking cuttings is another reliable method, especially for tender or hybrid varieties that may not survive winter or come true from seed. Softwood cuttings can be taken from non-flowering stems during the growing season, typically from summer into early autumn, to root and overwinter indoors.