Agastache foeniculum Blackadder
Agastache foeniculum Blackadder
Agastache foeniculum Blackadder
Agastache foeniculum Blackadder
Agastache foeniculum Blackadder
Agastache foeniculum Blackadder
Agastache foeniculum Blackadder
Agastache foeniculum Black Adder
Korean Mint, Anise Hyssop, Giant hyssop
The young plant took well last spring, with a lovely flowering in summer! It is still small, and I hope it will fill out a bit this year!
Sabine, 22/02/2026
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Description
Agastache 'Blackadder' is a robust perennial with electric blue flowers carried on black spikes; this beautiful perennial catches everyone's attention.
A hybrid variety between Agastache rugosa and A. foeniculum, this novelty is both very floriferous, robust, and easy to grow.
A bushy perennial with an upright habit, reaching a height of 80cm, Agastache 'Blackadder' blooms from June to September. It produces cylindrical flower spikes measuring 8 to 10cm in length, with black calyxes topped with bright electric blue tubular corollas. This intense black/blue combination contrasts with a magnificent light green, highly aromatic foliage offering a fruity scent composed of mint, liquorice, and lemon notes.
A melliferous plant, meaning it contains nectar that pollinating insects will transform into honey, Agastache is highly appreciated by bees, bumblebees, and even butterflies.
With good hardiness, the 'Blackadder' variety thrives in full sun, and it prefers rich and moist but well-drained soils.
When paired with Sedums, Rudbeckias, Gauras, or Stipa, it creates harmonious and natural scenes. For more graphic and contemporary scenes, combine it with Allium giganteum, Allium 'Summer Drummer', or Echinops ritro. The contrast of upright spikes and globular umbels works wonderfully!
Agastache foeniculum Blackadder in pictures
Flowering
Foliage
Plant habit
Botanical data
Agastache
foeniculum
Black Adder
Lamiaceae
Korean Mint, Anise Hyssop, Giant hyssop
Agastache anisata
Cultivar or hybrid
Planting and care
Agastache 'Blackadder' thrives in full sun or partial shade, sheltered from cold winds. It is a plant that withstands drought well. It is suitable for any type of well-drained soil, preferably moist and rich. If necessary, water the plant, especially during flowering. In spring, remove faded inflorescences and tidy up the clump. It is not particularly susceptible to diseases or pests that can hinder its flowering, except for powdery mildew, which can affect the leaves during dry spells.
Planting period
Intended location
Care
Planting & care advice
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Hardiness is the lowest winter temperature a plant can endure without suffering serious damage or even dying. However, hardiness is affected by location (a sheltered area, such as a patio), protection (winter cover) and soil type (hardiness is improved by well-drained soil).
The flowering period indicated on our website applies to countries and regions located in USDA zone 8 (France, the United Kingdom, Ireland, the Netherlands, etc.)
It will vary according to where you live:- In zones 9 to 10 (Italy, Spain, Greece, etc.), flowering will occur about 2 to 4 weeks earlier.
- In zones 6 to 7 (Germany, Poland, Slovenia, and lower mountainous regions), flowering will be delayed by 2 to 3 weeks.
- In zone 5 (Central Europe, Scandinavia), blooming will be delayed by 3 to 5 weeks.
In temperate climates, pruning of spring-flowering shrubs (forsythia, spireas, etc.) should be done just after flowering.
Pruning of summer-flowering shrubs (Indian Lilac, Perovskia, etc.) can be done in winter or spring.
In cold regions as well as with frost-sensitive plants, avoid pruning too early when severe frosts may still occur.
The planting period indicated on our website applies to countries and regions located in USDA zone 8 (France, United Kingdom, Ireland, Netherlands).
It will vary according to where you live:
- In Mediterranean zones (Marseille, Madrid, Milan, etc.), autumn and winter are the best planting periods.
- In continental zones (Strasbourg, Munich, Vienna, etc.), delay planting by 2 to 3 weeks in spring and bring it forward by 2 to 4 weeks in autumn.
- In mountainous regions (the Alps, Pyrenees, Carpathians, etc.), it is best to plant in late spring (May-June) or late summer (August-September).
The harvesting period indicated on our website applies to countries and regions in USDA zone 8 (France, England, Ireland, the Netherlands).
In colder areas (Scandinavia, Poland, Austria...) fruit and vegetable harvests are likely to be delayed by 3-4 weeks.
In warmer areas (Italy, Spain, Greece, etc.), harvesting will probably take place earlier, depending on weather conditions.
The sowing periods indicated on our website apply to countries and regions within USDA Zone 8 (France, UK, Ireland, Netherlands).
In colder areas (Scandinavia, Poland, Austria...), delay any outdoor sowing by 3-4 weeks, or sow under glass.
In warmer climes (Italy, Spain, Greece, etc.), bring outdoor sowing forward by a few weeks.
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