Agastache 'Blackadder'

hyssop (syn. Black Adder)

4 5 1 star 1 star 1 star 1 star 1 star (20 reviews) Write review
3 × 9cm pots £16.47 £13.50
in stock (shipped within 3-5 working days)
9cm pot £5.49
in stock (shipped within 3-5 working days)
Quantity 1 Plus Minus
Buy Agastache 'Blackadder' hyssop (syn. Black Adder): Distinctive violet, bottlebrush flowers

This perennial dies back to below ground level each year in autumn, then fresh new growth appears again in spring.

  • Position: full sun
  • Soil: well-drained, fertile soil
  • Rate of growth: average
  • Flowering period: July to October
  • Hardiness: fully hardy (borderline)

    Hyssops are great for adding height to a border, with whorls of long-lasting, tiny flowers arranged like a bottlebrush and pointed, aromatic fresh green leaves that are attractive to butterflies. They are short-lived though, and may need replacing every few years, especially after a cold or wet winter. 'Blackadder' has smoky, violet flowers on long spires from July to October. Try it as part of a Mediterranean scheme or in a sunny, well-drained border among ornamental grasses.

  • Garden care: Don't cut back the faded flower-stems until early spring, as they provide interest in the winter months. Lift and divide congested colonies in spring.

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Eventual height & spread

Eventual height and spread

Notes on Agastache 'Blackadder'

"The ultimate midsummer bee plant with soft, stubby blue bottle brushes tinged with black- purple -the antidote to sunny orange calendulas"

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Yes I would buy this product again


Used for a wildlife friendly garden Loved by bees and butterflies. Great quality plants delivered as always.




Great for polinators


Planted in border of mixed perennials.




Great plant. Good purchase.


I was so pleased with this plant. It flowered well in it's first year and was covered with bees so I recommended it to a bee loving friend. I have bought two Blue Fortune this year so hopefully they will do as well. They should make a good splash of colour alongside some pale yellow and orange English roses.

Welsh maid

South Wales


All good


Grew and bloomed healthily as expected. Waiting to see how it does in its second season


Suffolk Coastal


Worth the money


Plant was small in size when delivered but grew well once installed in a large container in a sunny position. Very fragrant and attractive to bees and when a section of plant got broken off I plunged it into another pot to see what would happen and, hey presto, had another plant! Better than dropping the broken section in the bin. Looking forward to spring to see how it fared through the winter weather. With all the wind, rain, snow and ice it needs to be hardy.

Wee Jeannie



Flowered all summer long


Grew to head height (1.8m) in very well-drained soil and with lots of sun, flowered from June to October followed by attractive seed heads and adored by bumble bees all summer. A best buy of 2018.

A Millennial Gardener



Nice purple spires and fragrant leaves


These took a while to get going and were a bit leggy in their first summer. The purple flowers were lovely and looked good planted near crocosmia. Bees love this plant. I'm hoping they'll be more established/bushy next year.






Like 'Blue Fortune' this is a superb bee plant which seems to out do even the Buddleja and Hebe as the most attractive flower for bees. Flower colour is stunning; deeper and darker than 'Blue Fortune', and lasts a very long time - June to mid-October. Leaves are wonderfully scented too. Very versatile, perfectly at home in a nature/meadow garden as well as in the border.




Love it


Wonderful in a contemporary, naturalistic planting.


East Anglia


Great plant for bees


I planted this in a border designed for bees. It is not hardy in the West Midlands, so I have taken cuttings to over winter. It is a spectacular plant that I have used in tubs on a patio in the past. It flowered until the first frosts. Great plant from Crocus, well packed and ready to put into the garden.


West Midlands



4.4 20


When is the best time to cut back Agastache Black Adder and Alabaster, do you cut them back to ground level? Can you take cuttings from them? Thank you.


We recommend that you don't cut back the faded flower-stems until early spring, as they provide interest in the winter months, but if you want to take cuttings, then now (late summer) is the perfect time - just make sure that the young plants are kept under cover in colder regions.


I bought Hyssop last year as part of an instant border and they looked great. I left the dead stems all winter but now there seems to be no new growth at the base of any of the plants. What has happened? Am I being impatient or will they still grow as I thought they were perennial? Thanks


Hello, These tend to be quite late into growth each year, so I would give them another month and all being well, they should start to emerge. If however your soil tends to be on the heavy side, then they may have died off as they are not quite fully hardy (particularly if they have to deal with the combination of low temperatures and wet feet).


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