Agastache ‘Blue Boa’

Giant hyssop 'Blue Boa'

Agastache ‘Blue Boa’ is a vibrant perennial known for its dense spikes of deep violet-blue flowers, blooming from midsummer to early autumn. Typically reaching 50-100cm in height, it excels in borders, pollinator gardens, and mixed containers.

Thriving in full sun and well-drained soil, it attracts bees, butterflies, and other pollinators. The aromatic, liquorice-scented foliage enhances its appeal. Low-maintenance and drought-tolerant once established, Agastache ‘Blue Boa’ adds enduring colour and texture to any garden landscape, making it a favourite among gardeners.

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Origin: Cultivar of horticultural origin, species native to East Asia (China, Japan, Korea, Russian Primorye, Taiwan, India, and Vietnam)
Genus: Agastache
Species / Cultivar: 'Blue Boa'
Common Name: Giant hyssop 'Blue Boa'
Synonym: Agastache rugosa 'Blue Boa'

Plant Biography

The genus Agastache, part of the Lamiaceae (mint) family, includes around 22 species of aromatic perennials, commonly known as giant hyssops or hummingbird mints. Native to North America and East Asia, these plants are valued for their medicinal, culinary, and ornamental uses.

Many Agastache species have been used in traditional non-Western medicine for centuries. In horticulture, Giant Hyssop is popular for its vibrant flowers, aromatic foliage, and ability to attract pollinators like bees, butterflies, and hummingbirds. Modern cultivars, such as Agastache ‘Blue Boa’, are bred for enhanced colour, fragrance, and garden performance.

Agastache 'Blue Boa'
Soil: Well drained
Soil that does not show much signs of moisture, either visibly or when handled.
Growth Rate: Fast
Expect to see prolific growth, especially during growing season.
Water Requirement: Low
Will grow in a drier position and is unlikely to need regular watering once established.
Maintenance: Low
Minimal skill or input needed beyond the basics, a very independent plant.
Situation: Full Sun
Wants direct, unfiltered sunlight most of the day, such as a south facing position.
Eventual Height: 0.5-1m
The plant's ultimate height in typical growing conditions.
Eventual Spread: 0.1-0.5m
The plant's ultimate spread in typical growing conditions.
Hardiness: Hardy
Survives unprotected in an average winter. May need protection in extreme long frosts.
Habit: Deciduous
Sheds all its foliage annually, so for a period of the year it will be without foliage.
Lifecycle: Perennial
This plant is persistant and does not die off after flowering. It will return each season indefinitely, if provided with suitable growing conditions.
Care & Size Guidance

Care & Size Guidance

Agastache ‘Blue Boa’ is a hardy perennial that thrives in full sun and well-drained soil. It typically grows to a height of 50-100cm and spreads about 20-50cm, making it ideal for borders and pollinator gardens. The plant is drought-tolerant once established and requires minimal maintenance. Regular watering during dry periods helps maintain vibrant blooms from midsummer to early autumn.

Prune back in late winter to encourage fresh growth. Its aromatic, liquorice-scented foliage attracts bees, butterflies, and other pollinators, enhancing garden biodiversity.


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