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Posted 03/21/2023 in Perennial

Agastache 'Black Adder'

Agastache 'Black Adder': A Standout in the Garden


Agastache 'Black Adder' is a perennial herb that brings striking beauty and versatility to any landscape. Known for its tall spires of deep blue-violet flowers, this plant is a favorite among gardeners and landscapers alike. Whether you’re looking to attract pollinators, add a pop of color, or introduce texture to your garden, 'Black Adder' has something to offer.

Description of the Plant and Flowers of Agastache 'Black Adder' 

Agastache 'Black Adder' is part of the mint family (Lamiaceae) and is native to North America. The plant typically grows between 2 to 3 feet tall and about 1 to 1.5 feet wide, making it an excellent choice for mid-border planting. The leaves are aromatic, lance-shaped, and a soft green color, providing a subtle contrast to the vibrant flowers.

The real showstopper, however, is the flowering spikes. From midsummer to early fall, 'Black Adder' produces an abundance of deep purple-black buds that open into tubular, deep blue-violet flowers. These blooms are arranged in dense spikes, creating a dramatic effect against the green foliage. The flowers are not only visually stunning but also emit a mild, pleasant fragrance.

Agastache 'Black Adder'  Value in the Landscape

Agastache 'Black Adder' is highly valued in the landscape for several reasons:

Pollinator Magnet: The flowers of 'Black Adder' are a favorite among bees, butterflies, and hummingbirds. Planting this in your garden will attract these beneficial pollinators, which can help enhance the health of your entire landscape.

Drought Tolerant: Once established, 'Black Adder' is highly drought-tolerant, making it a low-maintenance option for gardeners looking to conserve water. It thrives in well-drained soil and full sun, making it ideal for xeriscaping.

Versatility: This plant is versatile and can be used in various garden settings. It works well in cottage gardens, mixed borders, and wildlife gardens. It also pairs beautifully with other late-summer bloomers like Echinacea, Rudbeckia, and ornamental grasses.

Extended Bloom Time: 'Black Adder' has a long blooming period, providing color and interest in the garden from mid-summer through early fall. Its upright habit and height make it an excellent backdrop or middle-layer plant in perennial borders.

Deer and Rabbit Resistant: While many garden plants fall prey to deer and rabbits, Agastache 'Black Adder' is typically left alone, thanks to its aromatic foliage.

Interesting Facts About Agastache 'Black Adder'

Herbal Uses: Agastache species have been traditionally used in herbal medicine for their anti-inflammatory and digestive benefits. While 'Black Adder' is primarily grown for ornamental purposes, its leaves can be used to make a mild tea with a minty flavor.

Hybrid Origin: 'Black Adder' is a hybrid of Agastache rugosa (Korean mint) and Agastache foeniculum (anise hyssop). This blend gives it the hardiness of A. rugosa and the fragrance of A. foeniculum.

Resilience: Agastache 'Black Adder' is hardy in USDA zones 6-9, making it a reliable perennial in many climates. It can tolerate light frost, which allows it to bloom longer into the fall.

Ease of Care: This plant is not only drought-tolerant but also relatively pest and disease resistant. However, gardeners should watch out for common issues like aphids, spider mites, powdery mildew, and root rot, especially in poorly drained soils.

Agastache 'Black Adder' is a garden powerhouse that combines beauty, functionality, and ease of care. Its striking flowers, extended bloom time, and ability to attract pollinators make it a must-have for any landscape. Whether you're a seasoned gardener or just starting, adding 'Black Adder' to your garden will surely bring you joy season after season.

Other Plants You May Be Interested In:

Echinacea Sombrero® Summer Solstice

Lycoris squamigera

9e94b05793e12650cd101c0416af38e51b86ecca

About RightPlantz - RightPlantz is your go-to source for all things gardening. RightPlantz grows better gardeners.

Post Details

Latin Name
Agastache 'Black Adder'
Common Name
Black Adder Giant Hyssop
Planting Zone
Zone 6 Zone 7 Zone 8 Zone 9
Light Condition
Full Sun
Special Interest
Attracts Birds Attracts Butterflies Deer Resistant
Bloom Season
Spring
Flower Color
Purple
Height
2-3 ft
Spread
1.5-2 ft
Suggested Uses
Grouping Cottage Garden Pollinator Garden Perennial Border
Potential Pests
Agastache 'Black Adder' is fairly pest free but keep a look out for Aphids. Spider Mites. Powdery Mildew. Root Rot. Rust. Leaf Spot. Whiteflies, Slugs.

Plant Story

Agastache 'Black Adder': A Standout in the Garden


Agastache 'Black Adder' is a perennial herb that brings striking beauty and versatility to any landscape. Known for its tall spires of deep blue-violet flowers, this plant is a favorite among gardeners and landscapers alike. Whether you’re looking to attract pollinators, add a pop of color, or introduce texture to your garden, 'Black Adder' has something to offer.

Description of the Plant and Flowers of Agastache 'Black Adder' 

Agastache 'Black Adder' is part of the mint family (Lamiaceae) and is native to North America. The plant typically grows between 2 to 3 feet tall and about 1 to 1.5 feet wide, making it an excellent choice for mid-border planting. The leaves are aromatic, lance-shaped, and a soft green color, providing a subtle contrast to the vibrant flowers.

The real showstopper, however, is the flowering spikes. From midsummer to early fall, 'Black Adder' produces an abundance of deep purple-black buds that open into tubular, deep blue-violet flowers. These blooms are arranged in dense spikes, creating a dramatic effect against the green foliage. The flowers are not only visually stunning but also emit a mild, pleasant fragrance.

Agastache 'Black Adder'  Value in the Landscape

Agastache 'Black Adder' is highly valued in the landscape for several reasons:

Pollinator Magnet: The flowers of 'Black Adder' are a favorite among bees, butterflies, and hummingbirds. Planting this in your garden will attract these beneficial pollinators, which can help enhance the health of your entire landscape.

Drought Tolerant: Once established, 'Black Adder' is highly drought-tolerant, making it a low-maintenance option for gardeners looking to conserve water. It thrives in well-drained soil and full sun, making it ideal for xeriscaping.

Versatility: This plant is versatile and can be used in various garden settings. It works well in cottage gardens, mixed borders, and wildlife gardens. It also pairs beautifully with other late-summer bloomers like Echinacea, Rudbeckia, and ornamental grasses.

Extended Bloom Time: 'Black Adder' has a long blooming period, providing color and interest in the garden from mid-summer through early fall. Its upright habit and height make it an excellent backdrop or middle-layer plant in perennial borders.

Deer and Rabbit Resistant: While many garden plants fall prey to deer and rabbits, Agastache 'Black Adder' is typically left alone, thanks to its aromatic foliage.

Interesting Facts About Agastache 'Black Adder'

Herbal Uses: Agastache species have been traditionally used in herbal medicine for their anti-inflammatory and digestive benefits. While 'Black Adder' is primarily grown for ornamental purposes, its leaves can be used to make a mild tea with a minty flavor.

Hybrid Origin: 'Black Adder' is a hybrid of Agastache rugosa (Korean mint) and Agastache foeniculum (anise hyssop). This blend gives it the hardiness of A. rugosa and the fragrance of A. foeniculum.

Resilience: Agastache 'Black Adder' is hardy in USDA zones 6-9, making it a reliable perennial in many climates. It can tolerate light frost, which allows it to bloom longer into the fall.

Ease of Care: This plant is not only drought-tolerant but also relatively pest and disease resistant. However, gardeners should watch out for common issues like aphids, spider mites, powdery mildew, and root rot, especially in poorly drained soils.

Agastache 'Black Adder' is a garden powerhouse that combines beauty, functionality, and ease of care. Its striking flowers, extended bloom time, and ability to attract pollinators make it a must-have for any landscape. Whether you're a seasoned gardener or just starting, adding 'Black Adder' to your garden will surely bring you joy season after season.

Other Plants You May Be Interested In:

Echinacea Sombrero® Summer Solstice

Lycoris squamigera

9e94b05793e12650cd101c0416af38e51b86ecca

About RightPlantz - RightPlantz is your go-to source for all things gardening. RightPlantz grows better gardeners.

Special Care Instructions

Special Care Instructions for Agastache 'Black Adder'

Planting Location:

  • Choose a spot with full sun for the best flowering performance. Agastache 'Black Adder' needs at least 6 hours of direct sunlight daily to thrive.
  • Ensure the soil is well-draining. This plant does not tolerate wet or soggy conditions, which can lead to root rot.

Watering:

  • Water regularly during the first growing season to establish a deep root system.
  • Once established, 'Black Adder' is drought-tolerant and only needs occasional watering. Allow the soil to dry out between watering sessions.

Soil Requirements:

  • Plant in average to lean soil. Too much fertility can cause the plant to become leggy and reduce flower production.
  • If your soil is heavy or clay-like, consider amending it with sand or gravel to improve drainage.

Fertilization:

  • Fertilizing is generally not necessary. If desired, apply a balanced, slow-release fertilizer in early spring, but avoid over-fertilizing as this can lead to excessive foliage growth and fewer flowers.

Pruning:

  • Deadhead spent flowers regularly to encourage continuous blooming throughout the season.
  • In late fall or early spring, cut back the stems to the base of the plant to maintain a tidy appearance and encourage vigorous new growth in the spring.

Mulching:

  • Apply a light layer of mulch around the base of the plant in early spring to help retain moisture and suppress weeds. Avoid heavy mulching as this can trap moisture and lead to root issues.

Winter Care:

  • In colder climates (zones 6-7), provide a protective mulch layer in late fall to insulate the roots during winter. In warmer climates, this is not necessary.
  • 'Black Adder' is hardy, but in areas with harsh winters, you might consider covering the plant with a frost cloth during extreme cold spells.

Pest and Disease Management:

  • Monitor for common pests like aphids, spider mites, and whiteflies. These can be controlled with insecticidal soap or by spraying them off with a strong jet of water.
  • To prevent powdery mildew, ensure good air circulation around the plant by spacing it properly and avoiding overhead watering.

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