Agastache 'Blackadder'
Agastache 'Blackadder'
Agastache 'Blackadder'
Agastache 'Blackadder'
Agastache 'Blackadder'

Agastache 'Blackadder'

"Giant hyssop"

Agastache 'Blackadder'

1 bare root — £5.95

Spring planting season is currently closed 
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Delivery schedule

Orders placed until 29 February 2025
You can expect your order in February/March 2025

Orders placed 1 March - 15 April 2025
You can expect your order in March/April 2025

Orders placed 16 April - 15 May 2025
You can expect your order within 10 business days

Available for (pre)ordering again in December
Free delivery on UK orders over £50
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Shipping to the UK

UK orders over £50
Free shipping

UK orders under £50
£4.99

Northern Ireland orders under £50
£5.99

More info

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Description

Introduce long-lasting colour, structural interest and a subtle aniseed aroma to your garden with impressive Agastache 'Blackadder'. Not only does this bushy giant hyssop pad out a patch with very attractive flowers during summer and autumn, but it will also be a welcome pit-stop for bees, butterflies and other pollinators. Upright flower spikes in an eye-catching shade of deep purple-blue are dotted with masses of small lilac-coloured flowers which gives the blooms an overall purple haze appearance, while the leaves emit a fresh, spicy fragrance.

Agastache 'Blackadder' tolerates heat and drought well, thriving in a free-draining soil. Its tolerance to what can be harsh summer conditions makes this an undemanding and reliable choice for the border. This giant hyssop is quite hardy, tolerating winter temperatures down to around -10°C in a sunny, sheltered position with free-draining soil. In areas with fairly mild winters, Agastache 'Blackadder' will grow back bigger and bushier each year!

Traditionally, Agastache was utilized for its medicinal qualities, thanks to its essential oils that would hold antimicrobial, anti-inflammatory, and digestive attributes.

Key features

  • Perfect for pots

  • Comes back every year

  • Fragrant

  • Attractive to wildlife

  • Loved by pollinators

  • Thrives well in full sun

  • In peat-free compost

  • Low maintenance

  • RHS Award (AGM)

  • Drought tolerant

  • Fully hardy

  • Rodent resistant

Specs & details

  • Botanical name

    Agastache 'Blackadder' syn. Agastache 'Black Adder'

  • Flower colour

    Purple, blue, near-black

  • Plant size

    1

  • Established height

    70cm-1m

  • Established spread

    20-30cm

  • Plant spacing

    6 plants per m2

  • Leaf colour

    Green

  • Habit

    Clump-forming
    Upright

  • Life cycle

    Short-lived perennial

  • Hardiness

    Fully hardy

  • Years to establish

    1-2 years

  • Sunlight

    Full sun

  • Position

    Sheltered
    Exposed

  • Suitable for

    Pots
    Large containers
    Borders
    Gravel gardens
    Wildlife gardens
    Cottage gardens
    Low maintenance gardens

  • Soil acidity

    Any

  • Soil moisture

    Free draining

  • Soil type

    Clay
    Multipurpose compost

  • RHS Award (AGM)

    Yes

  • Growing skill

    Easy to grow

  • Scented

    Yes

  • Pollinator-friendly

    Yes

  • Mouse resistant

    Yes

  • Rabbit resistant

    Yes

  • Deer resistant

    Yes

  • Toxicity

    No report

Plant calendar

JanFebMarAprMayJuneJulyAugSepOctNovDec
  • Planting
  • Flowering

Useful information

    • Soak the Agastache 'Blackadder' roots in water for 3-6 hours prior to planting

    • Plant your "Giant hyssop" bare roots into temporary pots with a multipurpose compost in spring and grow-on in a sheltered spot outdoors

    • Choose a pot which comfortably fits the bare roots. Some have a noticeable crown which should be just below the soil surface with any top growth exposed. Some varieties are a length of root which should be planted lengthways and shallowly (1-2cm deep).

    • Plant out into borders or permanent containers in late spring or early summer once in full growth. Choose a position in sun or shade depending on the variety.

    Read all planting & care instructions

  • Orders placed until 29 February 2025
    You can expect your order in February/March 2025

    Orders placed 1 March - 15 April 2025
    You can expect your order in March/April 2025

    Orders placed 16 April - 15 May 2025
    You can expect your order within 10 business days

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