Blue Giant-hyssop
Agastache foeniculum
Last reviewed: July 2026
Agastache foeniculum is a native prairie forb blooming blue-purple from June through September across the northern Great Plains and upper Midwest. This drought-tolerant wildflower attracts bees, butterflies, and hummingbirds.
Light
full sun
Water
medium
Size
24"–48" H × 18"–24" W
Bloom
Jun, Jul, Aug, Sep
Native to
CO, IA, ID, IL and 9 more states
Pollinators
bees, butterflies, hummingbirds
Deer
Resistant (per Prairie Moon Nursery)
Blue giant-hyssop is an upright perennial herb with fragrant, mint-scented foliage and dense spikes of small blue to purple flowers. It blooms continuously from June through September, creating an attractive vertical accent in sunny gardens. This native plant forms neat clumps and has a tidy, structured appearance that works well in formal landscapes.
Growing Blue Giant-hyssop
Grow Blue Giant-hyssop in full sun and medium water. Mature plants reach 24 to 48 inches tall and spread 18 to 24 inches wide. Expect low maintenance to keep it looking intentional in a front yard.
In an HOA neighborhood
Blue Giant-hyssop is an HOA-friendly choice. Maintenance level: low. Tidiness: 4 out of 5.
Works well in: front yard, foundation, street edge, mid zone.
- May self-seed if not deadheaded
Wildlife value
Excellent pollinator magnet that attracts bees, butterflies, and hummingbirds throughout its long blooming season. The seeds also provide food for goldfinches and other small birds in fall.
Common questions
- When does Blue Giant-hyssop bloom?
- Agastache foeniculum blooms from June through September, producing spikes of blue to purple flowers that are highly attractive to pollinators.
- What pollinators visit Blue Giant-hyssop?
- This native wildflower attracts a diverse range of pollinators including native bees, butterflies, and hummingbirds. The tubular flowers are particularly well-suited for long-tongued pollinators.
- Where is Agastache foeniculum native?
- Blue Giant-hyssop is native to the northern Great Plains and upper Midwest, including Colorado, Iowa, Illinois, Minnesota, Montana, North Dakota, Nebraska, South Dakota, Wisconsin, and Wyoming.
- What growing conditions does Blue Giant-hyssop prefer?
- This prairie native thrives in full sun and tolerates a wide range of moisture conditions from dry to moderately wet soils. It is quite drought tolerant once established.
- Is Blue Giant-hyssop HOA-friendly?
- Blue Giant-hyssop is generally an HOA-friendly choice in the right placement, with low maintenance.
Native range data from the USDA PLANTS Database and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Ready to grow Blue Giant-hyssop? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
Not sure where to start? Take the 2-minute yard quiz