Agastache Black Adder (Giant Hyssop)

Hardy and reliable, Agastache ‘Black Adder’ (Giant Hyssop) is a charming herbaceous perennial boasting bottle-brush, terminal spikes, 6-8 in. long (15-20 cm), packed with fragrant, tubular, two-lipped red-violet flowers emerging from dark buds.

Hardy and reliable, Agastache 'Black Adder' (Giant Hyssop) is a charming herbaceous perennial boasting bottle-brush, terminal spikes, 6-8 in. long (15-20 cm), packed with fragrant, tubular, two-lipped red-violet flowers emerging from dark buds. Blooming from mid-summer to fall, they provide a remarkably long floral display and add color as well as a lovely spiky texture to the garden.

  • Forms upright clumps up to 2-3 feet tall (60-90 cm) and 18-24 in. wide (45-60 cm), with aromatic, blue-green leaves which exude an anise scent when crushed.
  • Provides a bold visual impact in beds and borders, cottage gardens, gravel gardens, butterfly gardens, or Mediterranean gardens over a very long season.
  • Ideal to add color to the late-season garden when many other plants are fading.
  • Creates a stunning effect when mixed with other perennials or planted en masse.
  • Attracts streams of hummingbirds, butterflies, and other beneficial pollinators.
  • Easily grown in full sun, in average, dry to medium moisture, well-drained soils. Good drainage is particularly important.
  • Drought, dry soil, and heat tolerant once established.
  • Generally disease and pest-free (might occasionally be subject to powdery mildew) and resistant to deer and rabbits.
  • Trim back stems in late autumn to reduce windrock. Prune flowered stems back in spring.
  • Root semi-ripe cuttings in late summer and overwinter under cover; propagate by division in spring. This cultivar is sterile.

Requirements

Hardiness 6
– 9

Heat Zones 5
– 12

Climate Zones 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Agastache – Hyssops
Exposure Full Sun
Season of Interest Summer (Mid,Late)Fall
Height 2'
– 3'
(60cm
– 90cm)
Spread 1'
– 2'
(30cm
– 60cm)
Spacing 18″
– 24″
(45cm
– 60cm)
Water Needs Average
Maintenance Low
Soil Type Chalk, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Fragrant, Showy
Tolerance Deer, Drought, Rabbit
Attracts Bees, Butterflies, Hummingbirds
Garden Uses Banks and Slopes, Beds and Borders
Garden Styles Gravel and Rock Garden, Informal and Cottage, Mediterranean Garden