Images Depict Mature Plants
Black Adder Agastache
Agastache ‘Black Adder’
Black Adder Agastache is a pollinator plant with real presence. The dark buds and purple flower spikes stand out in a sunny border, and the fragrant foliage makes it practical for deer-prone gardens. Plant it where the drainage is sharp, repeat it in groups for the best hummingbird and butterfly show, and resist the urge to overwater or overfeed it.
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Dark Purple Agastache for Pollinator Gardens, Hummingbirds, and Sunny Borders
Black Adder Agastache Adds Dark Drama to Sunny Gardens
Black Adder Agastache is a long-blooming perennial grown for its nearly black buds, smoky violet-purple flower spikes, and fragrant green foliage. Also known as Agastache Black Adder, Black Adder Giant Hyssop, or Black Adder Hummingbird Mint, this upright perennial brings strong vertical color to sunny borders from summer into early fall.
The flower spikes have a deeper, more dramatic look than many lighter blue Agastache varieties. Dark buds open into tubular purple blooms that stack along bottlebrush-style spikes, creating movement, texture, and rich color in pollinator gardens, cottage gardens, dry borders, and mixed perennial beds.
A Pollinator Magnet for Hummingbirds, Bees, and Butterflies
Black Adder Agastache is one of those plants that makes a sunny garden feel alive. The nectar-rich flowers attract hummingbirds, bees, butterflies, and other beneficial pollinators throughout the warm season.
Plant it where you can enjoy the activity up close, such as near a patio, walkway, porch, or seating area. Repeating Black Adder in groups or drifts creates a stronger flower display and makes it easier for pollinators to find. It pairs especially well with Coneflowers, Black-Eyed Susans, Yarrow, Catmint, Salvia, Bee Balm, Russian Sage, and ornamental grasses.
Fragrant Foliage Deer and Rabbits Tend to Avoid
Black Adder Agastache has aromatic foliage with a minty, anise-like scent when crushed. That fragrance adds another sensory layer to the garden and helps make the plant less appealing to deer and rabbits than many softer perennials.
Use it in sunny beds where you want reliable color with better browsing resistance. No plant is completely deer-proof, especially during heavy pressure, but aromatic perennials like Agastache are smart choices for homeowners who want flowers, pollinators, and lower-maintenance performance.
Full Sun, Good Drainage, and Strong Heat Tolerance
Plant Black Adder Agastache in full sun for the best flower production and strongest upright habit. It can tolerate light shade, but too much shade may reduce bloom and make the plant less sturdy.
Well-drained soil is essential. Agastache performs best in average to lean soil that does not stay wet, especially through winter. Once established, Black Adder handles heat and dry spells well, making it useful for sunny slopes, low-water landscapes, dry borders, and well-drained container plantings.
Long Blooming Color with Simple Seasonal Care
Black Adder Agastache blooms over a long season, especially when spent flower spikes are removed. Deadheading helps keep the plant tidy and can encourage additional blooms, while the upright stems continue to add structure to the border.
In colder climates, leave some stems standing through winter to help protect the crown and provide garden texture. Cut back old stems in late winter or early spring, before new growth begins. Avoid wet winter soil and heavy fertilizing, both of which can reduce long-term performance.
| Hardiness Zone: | 6-9 |
|---|---|
| Mature Height: | 2 to 3 Feet |
| Mature Width: | 1.5 to 2 Feet |
| Sunlight: | Full sun preferred; tolerates light shade |
| Soil | Average to lean, very well-drained soil |
| Water | Water regularly during establishment; drought tolerant once established |
| Bloom Time / Color | Summer into early fall; smoky violet-purple to blue-purple flowers emerging from nearly black buds |
| Foliage: | Fragrant green foliage with minty, anise-like scent when crushed |
| Ornamental Features | Nearly black buds, purple bottlebrush flower spikes, fragrant foliage, upright habit, long bloom season |
| Wildlife Value | Attracts hummingbirds, butterflies, bees, and other beneficial pollinators |
| Resistance | Generally considered deer resistant and rabbit resistant; drought tolerant once established; heat tolerant |
| Landscape Uses | Pollinator gardens, hummingbird gardens, cottage gardens, sunny borders, dry gardens, herb gardens, mass plantings, containers, meadow-style plantings |
How to Care for Black Adder Agastache
Be sure to read our planting instructions to ensure a healthy and happy Black Adder Agastache Plant for years to come!
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How should I plant Black Adder Agastache?
Plant Black Adder Agastache in full sun with well-drained soil. Dig a hole about twice as wide as the root ball and just as deep as the container. Set the crown level with the surrounding soil, backfill with loosened native soil, and water thoroughly after planting. Space plants about 18 to 24 inches apart so each clump has room for mature growth and good airflow. Avoid low, wet areas or heavy clay that stays soggy through winter. If drainage is a concern, plant in a raised bed, slope, berm, or container.
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How often should I water Black Adder Agastache after planting?
Water Black Adder Agastache deeply after planting, then keep the soil lightly moist while the roots establish. During the first growing season, water when the top few inches of soil become dry, especially during hot or windy weather. Once established, Black Adder Agastache is drought tolerant and usually needs less supplemental water than many flowering perennials. Water deeply but infrequently during extended dry spells, and avoid frequent shallow watering or soggy soil.
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When should I fertilize Black Adder Agastache?
Fertilize Black Adder Agastache lightly in spring only if the soil is very poor. A thin layer of compost or a modest application of slow-release balanced fertilizer is usually enough. Avoid heavy feeding. Agastache often performs best in average to lean soil, and too much fertilizer can encourage soft, floppy growth. Full sun, sharp drainage, and moderate watering are more important than frequent fertilizer.
When and how should I prune / cut back Black Adder Agastache?
Deadhead spent flower spikes during the bloom season to keep Black Adder Agastache tidy and encourage continued flowering. Cut individual flower stems back to a lower set of leaves or side shoots. In late winter or early spring, cut old stems back close to the ground before new growth begins. In colder regions, leave stems standing through winter for extra crown protection and beneficial insect habitat, then clean up once spring growth starts.
