Agastache Blackadder

Agastache ‘Black Adder’: A Fragrant Perennial for Vibrant Borders

Agastache ‘Black Adder’, also known as Giant Hyssop ‘Black Adder’, belongs to the Lamiaceae family of plants and is a hardy herbaceous perennial. This sterile cultivar showcases deep purple-violet flowers on spikes that reach approximately 3 feet in height during the summer and fall. Its attractive flowers are a perfect addition to borders, alluring butterflies to the garden. The aromatic leaves of Agastache ‘Black Adder’ emit a hint of anise, and the plant maintains visual interest even through the winter season.

Description and Cultivation

The tubular, two-lipped flowers of Agastache ‘Black Adder’ adorn spikes that measure around 8 inches (20 cm) in length. The blue-green leaves form a clump from which the flower spikes emerge. This drought-tolerant and heat-tolerant plant thrives once established and is resistant to deer and rabbits.

Agastache ‘Black Adder’ is a hardy and reliable perennial that showcases bottle-brush-like terminal spikes, ranging from 6 to 8 inches (15-20 cm) long. The fragrant flowers emerge from dark buds, displaying a red-violet color. With a blooming period extending from mid-summer to fall, this perennial provides a long-lasting floral display while contributing a spiky texture to the garden.

Forming upright clumps reaching 2-3 feet (60-90 cm) in height and 18-24 inches (45-60 cm) in width, Agastache ‘Black Adder’ features aromatic blue-green leaves that release an anise scent when crushed. It creates a bold visual impact in various garden styles, including beds, borders, cottage gardens, gravel gardens, butterfly gardens, and Mediterranean gardens. Notably, it adds vibrant color to late-season gardens when other plants may be fading, making it a standout choice. Mixing it with other perennials or planting it in mass displays enhances its stunning effect. Furthermore, its presence attracts hummingbirds, butterflies, and other beneficial pollinators.

Characteristics:

Agastache ‘Black Adder’ thrives in full sun and well-drained soil with average to dry moisture levels. Good drainage is particularly important. Once established, it demonstrates excellent tolerance to drought, dry soil, and heat. The plant is generally disease and pest-free, although powdery mildew may occasionally occur. It is also resistant to deer and rabbits. In late autumn, trimming back the stems reduces windrock, while pruning the flowered stems in spring promotes new growth.

Propagation can be done through root semi-ripe cuttings in late summer or division in spring. It is crucial to plant Agastache ‘Black Adder’ in full sun, in rich and fertile, well-drained soil. It does not tolerate wet soil during winter.

Agastache Blackadder
Giant Hyssop Blackadder or Agastache ‘Blackadder’

Cultivation and Care of Agastache ‘Black Adder’:

Planting: Agastache ‘Black Adder’ thrives in full sun but can tolerate partial shade. It performs best in well-drained soil, which can be enriched with compost or manure before planting. Space the plants 18-24 inches apart.

Watering: Once established, Agastache ‘Black Adder’ is drought-tolerant. However, regular watering during the first year after planting is beneficial. Water deeply and infrequently to encourage deep root growth.

Fertilizer: Agastache ‘Black Adder’ does not require frequent fertilization. Applying a light fertilizer in the spring will promote new growth.

Pruning: Minimal pruning is necessary for Agastache ‘Black Adder’. Deadheading spent flowers encourages continuous blooming. In the fall, cutting back the plant by one-third of its height will stimulate new growth in the following spring.

Overwintering: Agastache ‘Black Adder’ is hardy in USDA zones 5-9. In colder climates, it is advisable to mulch around the plants to protect them from the cold during winter.

By following these cultivation and care tips, you can enjoy the vibrant and fragrant presence of Agastache ‘Black Adder’ in your garden. Its attractive flowers, long blooming period, and ability to attract pollinators make it a valuable addition to any landscape.

Agastache Blackadder
Giant Hyssop Blackadder or Agastache Blackadder
Agastache Blackadder
Purple Violet Agastache ‘Blackadder’
Agastache Blackadder
Agastache ‘Blackadder’ at Kew Gardens
Agastache Blackadder
Beautiful Agastache Blackadder
Agastache Blackadder
Giant Hyssop Blackadder or Agastache Blackadder in a border at Kew Gardens
Agastache Blackadder
Violet and purple flower of Agastache Blackadder
Agastache Blackadder
Purple flowers of Agastache ‘Black Adder
Agastache Blackadder
Agastache Blackadder

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