Agastache ‘Black Adder’-Giant Hyssop

Agastache ‘Black Adder’ on 6-29-14, #230-3.

Giant Hyssop

Agastache ‘Black Adder’

Agastache rugosa x Agastache foeniculum

ah-gas-TAH-kee   roo-GO-suh  X  ah-gas-TAH-kee   fen-IK-yoo-lum

Agastache ‘Black Adder’ is a hybrid between Agastache rugosa and Agastache foeniculum.

Agastache rugosa (Fisch. & C.A.Mey.) Kuntze is the correct scientific name for one parent. It was described as such by Carl Ernst Otto Kuntze in Revisio Generum Plantarum in 1891. It was first described as Lophanthus rugosus by Friedrich Ernst Ludwig von Fischer and Carl Anton von Meyer in Index Seminum in 1835.

Agastache foeniculum (Pursh) Kuntze is the correct and accepted scientific name of the other parent. It was first described by that name by Carl Ernst Otto Kuntze in Revisio Generum Plantarum in 1891. It was first described as Stachys foeniculum by Frederick Traugott Pursh in Flora Americae Septentrionalis in 1813.

The genus, Agastache J.Clayton ex Gronov., was first described by John Clayton and Johan Frederik Gronovius in Flora Virginia in 1762. Plants of the World Online by Kew lists 22 accepted species of Agastache, which is the same as the 2013 version of The Plant List. The Plant List hasn’t been maintained since 2013, so Kew launched Plants of the World Online in 2017.

Hyssop is a Greek word meaning “many spikes” or “many ears of corn” giving reference to their flower spikes.

I bought my first Agastache ‘Black Adder’ in the spring of 2014. I put it in the bed next to the side porch. It did very well and I really loved the plant. We have a few deer but they normally don’t venture too close to the house. However, they did just to eat a few flowers off this plant. Kind of strange, though, because Agastache is supposed to be deer resistant. Sadly, though, this plant did not return the following spring and I couldn’t find another one. A whole bed of these would be AWESOME!


Agastache ‘Black Adder’ on 6-29-14, #230-4.

One common name for the Agastache is Giant Hyssop, although the many species also have their own common names. One of the parents of A. ‘Black Adder’, Agastache foeniculum, is Anise Hyssop. The other parent, Agastache rugosa, is known as Korean Mint, Purple Giant Hyssop, etc.

Let me take you a bit further into the family in which Agastache is a member of… The Lamiaceae Family. The 2013 version of The Plant list said the family is comprised of 245 accepted plant genera, 7,886 accepted species and 1,490 that are unresolved. There are another 734 accepted infraspecific names. There were a total of 20,616 synonyms (including infraspecific names). These numbers may be somewhat different now. It is a family referred to as the mint or deadnettle family. It included many herbs used in cooking such as basil, the many mints, sage, savory, marjoram, oregano, thyme, lavender, and perilla.

Agastache hybrids are said to have better flowers and be more winter hardy. They come in a variety of colors including shades of red, orange, pink, yellow and white.


Agastache ‘Black Adder’ after the deer attack on 7-12-14, #231-2.

HEIGHT: 2-3’ +
LIGHT: Full sun to part shade
WATER: Medium
SOIL: Average, well-drained soil
MAINTENANCE: Deadhead flowers to promote additional bloom.
USES: They attract butterflies

In cooler areas where overwintering could be a problem, plants should be located in a southern exposure. Leaf and flower stems should not be removed. Loose mulch should be used to protect against root rot (such as coarse mulch like bark.)

I hope you enjoyed this page and maybe found it useful. If you have any comments, questions or suggestions, I would like to hear from you. Please click on “like” if you visited this page. It helps us bloggers stay motivated. 🙂 You can check out the links below for further reading. The links take you directly to the genus and species of this plant.


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