Agastache
Family Lamiaceae — Genus Agastache
Agastache, commonly known as hyssop or hummingbird mint, is a genus of aromatic perennials that have become indispensable in pollinator and xeriscape gardens. Their long spikes of tubular flowers bloom from midsummer through frost, providing vital nectar for hummingbirds, butterflies, and bees during the late-season period when many other nectar sources have faded. The aromatic foliage, reminiscent of anise or mint, adds another sensory dimension to the garden.
Quick Facts
Bloom Time
Agastache flowers from midsummer through frost, producing dense spikes of tubular flowers that are irresistible to hummingbirds, butterflies, and bees. The blooms appear continuously on new growth, and deadheading prolongs the display. Many species also feature aromatic foliage that releases fragrance when brushed or crushed.
Size and Growth Habit
Agastache grows 2 to 4 feet tall with an upright, bushy habit. The square stems (characteristic of the mint family) carry aromatic, toothed leaves. Flower spikes can reach 6 to 12 inches in length and are produced continuously throughout the blooming season on new growth.
Hardiness Zones
Agastache species vary in hardiness. Western natives like A. rupestris are hardy in Zones 5 through 10, while eastern species like A. foeniculum extend to Zone 4. Hybrid cultivars generally perform well in Zones 5 through 9. Good drainage is more important than cold hardiness for winter survival.
Light Requirements
Agastache demands full sun with at least 6 to 8 hours of direct sunlight daily. It evolved in open, sunny habitats and produces the most flowers and most aromatic foliage in full sun exposure.
Soil and Water Requirements
Agastache thrives in well-drained, lean to moderately fertile soil. It is highly drought-tolerant once established and performs poorly in rich, moist soils, which promote soft, floppy growth. Excellent drainage is critical for winter survival, as wet winter soils kill more plants than cold temperatures.
Pruning
Deadhead spent spikes to encourage continuous blooming. Cut plants back by one-third in late spring if they become leggy. Leave dried stems standing through winter to protect the crown, then cut back in early spring when new growth appears.
Summer Care
Summer is agastache's glory season. Water sparingly — overwatering is the most common mistake. Enjoy the constant parade of hummingbirds and butterflies visiting the flowers. Plants are remarkably self-sufficient in summer heat.
Winter Care
In colder zones, ensure excellent drainage to prevent winter crown rot. Leave dried stems standing to protect the crown from freeze-thaw cycles. A light gravel mulch around the base improves drainage. Avoid heavy organic mulch, which holds moisture against the crown.
Companion Plants
Pests and Diseases
- Powdery mildew: Can occur in humid conditions. Ensure good air circulation and avoid overhead watering.
- Crown rot: The primary killer, caused by wet winter soils. Ensure excellent drainage.
- Agastache is generally pest-free. Its aromatic oils deter most insects and browsing animals.
Common Varieties
Toxicity
Non-toxic to pets and humansAgastache is completely non-toxic and in fact several species are used as culinary and medicinal herbs. Anise hyssop (A. foeniculum) leaves make a pleasant tea with an anise-like flavor. All species are safe around children and pets.
Care Difficulty
Agastache is a low-maintenance perennial that thrives on neglect in well-drained soil and full sun. The key requirement is excellent drainage, especially in winter. Once this is provided, agastache rewards with months of continuous bloom and constant pollinator activity.