Anise hyssop

I no longer remember what prompted me to purchase my first anise hyssop, and I’m pretty sure I had no idea what a trooper it would turn out to be as our summers have become hotter and drier and as deer browsing has increased. These days I wouldn’t want to be without it, and you shouldn’t be either.

Anise hyssop (Agastache foeniculum) is a perennial in the mint family that is native to much of the northern section of North America (northern Colorado to Wisconsin and in Canada from Ontario west to British Columbia).  It goes by several common names:  giant hyssop, lavender hyssop, and blue giant hyssop. However, it is NOT closely related to hyssop (Hyssopus spp.), a European plant traditionally used as a healing herb, nor to anise (Pimpinella anisum), a completely different plant in the carrot family.  It does have lovely purplish blue flower spikes that last a long time and fragrant leaves with a licorice scent.  No doubt that licorice scent deters deer, though my research indicates that rabbits may eat it.  So far, neither pest has nibbled on my anise hyssop.

By the way, some humans consume the licorice-flavored leaves of Agastache foeniculum, usually in teas.  As with any plant that’s considered safe to eat, be sure you have the correct plant and that it was not grown in an area treated with pesticides.  Univ.of Minnesota Extension.

Deer may not like this plant, but pollinators sure do. In fact, it has been identified by the Xerces Society as one of the top plants for pollinators.   Bees are particularly fond of it, especially bumblebees.  I’d observed this in my own garden, but I was amazed to learn that mass plantings of giant blue hyssop were at one time employed to support apiaries in the Midwest and Canada.  Butterflies and hummingbirds are also regular visitors, and birds may eat the seeds.

Anise hyssop is easy to grow in either full sun or partial shade, and is not fussy about soil or moisture, though it does need decently-drained soil.  Once it’s established, it is drought tolerant — a trait that’s becoming more and more important.  Despite its height — 2 to 4 feet tall — it usually needs no staking.  The period of bloom is long, starting here around the end of June and continuing to late summer or early fall.  It is generally problem-free, though excess water can lead to root rot.

Another thing I love about anise hyssop is its tendency to self-sow and to spread by rhizomes, making for easy propagation.  On top of all that, you can deadhead the flowers to promote additional blooms.  By pruning the plant lightly during the growing season you can encourage branching as well as new flowers. It should come as no surprise that this too-good-to-be-true plant was named the 2019 Herb of the Year™ by the International Herb Association.

If you want to start it by sowing seeds, that’s easily done, and the seeds are readily available online.  Seeds can either be started indoors 5-8 weeks before the last frost in spring or sown directly in garden beds or containers. The seeds need light to germinate, and it’s important to just barely cover the seeds with soil. Germination time is 1-4 weeks. Germination is reportedly improved with a 30-day period of cold, along with moist stratification before sowing.

Once you’ve got a colony going, you may want to start saving some seeds.  To save seeds, cut off a mature seed head in fall and place it in a bag.  Alternatively, you can place a bag over a fading flower to hold the seeds as they dry.  Whichever method you choose, you’ll need to allow plenty of time for drying in the bag.  The small dark seeds can be difficult to separate from the dry seed heads, but one authority suggests you simply plant all the contents at the bottom of the bag — the small plant fragments, dust, seeds and all.  I find that my plants do enough self-seeding to suit my needs.

I am very fond of the straight species, but there are several cultivars. Be aware that some cultivars are not as supportive of pollinators as the straight species.  In addition, some of the cultivars are fussier about soil than the species, and require well-drained soil.  For advice on the cultivars, I turned to Pat Chadwick, Master Gardener Extraordinaire and regular contributor to these pages.  Pat has grown several of the following cultivars, and her comments are included below:

• 

  ‘Blue Fortune’ — long bloom period because it does not set seed; recipient of the Royal Horticulture Society’s Award of Garden Merit in 2003.   ‘Blue Fortune’ is Pat Chadwick’s favorite. She says,” I can’t do without this plant!! It’s an absolute bee and butterfly magnet. I once tried to count all the insects that were flitting around the plant, but there were too many to count. I also like the fact that the calyxes show color long after the blossoms are finished, which gives this plant added value as an ornamental.”

• ‘Alabaster’ – has creamy-white flowers on 3′ plants with lighter green foliage that is less bushy than the species.
• ‘Black Adder’ – a hybrid with dark buds and red-violet flowers, less robust than the species.  This is another Pat Chadwick favorite even though it has not been long lived for her.
• ‘Blue Blazes’ – a tall hybrid of A. foeniculum and Agastache ‘Desert Sunrise’ introduced by High Country Gardens; lavender purple blooms.
• ‘Blue Fountain’/’Blue Spike’ – clear blue flowers.
• ‘Golden Jubilee’ – an All American Selection Winner (2003) with gold to lime-green foliage and lavender-blue flowers. Self-seedlings are mixed, some golden and some not.  According to Pat Chadwick, this cultivar “pops up all over the place, so I pull out what I don’t want and transplant the rest as needed to give a pop of chartreuse in the garden. Great plant and the pollinators love it.”
• ‘Purple Haze’ – a hybrid with narrow flower spikes that are of less interest to large native bees but attracts many smaller pollinators.
• ‘Red Fortune’ – a hybrid with pink flowers that are not nearly as attractive to pollinators as the species.

• 

  ‘Apricot Sunrise’ — an erect, shorter plant with tubular, orange-apricot flowers.  It is sometimes identified as Agastache aurantiaca x A. coccinea and by the common name hummingbird mint.  Pat Chadwick has noted that it “has much finer foliage than most of the other hybrids I’ve grown and is tough as nails.”

If you’d like to try one or more of these hybrids, you may need to amend your soil to maximize drainage.  Fall is the best time to plant.  Be aware that pruning or cutting back in the fall or winter may adversely impact cold hardiness.

Whether you’re looking to create a pollinator garden, to add a drought-tolerant long-bloomer to your perennial border, or simply love the shade of blue, you’ll find that anise hyssop will fit the bill. I recently transplanted some of the seedlings from my garden into containers on my deck, where they not only look lovely all summer but also encourage the bees that are needed by my containerized tomato plants.  What more could a gardener ask?

SOURCES:

Featured photo:  Cathy Caldwell

USDA Plants Database/Agastache foeniculum

“Anise hyssop, Agastache foeniculum,” Univ.Wisconsin Ext.

“Agastache foeniculum,” NC State Ext.

“Anise Hyssop for the Perennial Garden,” Penn.State Ext.

“Agastache ‘Blue Fortune’, Missouri Botanical Garden PlantFinder

“Tulsi Basil and Anise Hyssop: Easy, Useful, and Adaptable,” Maryland Grows BLOG/Univ.of Maryland Ext.

“Anise Hyssop hybrids almost too good to be true,”  University of Georgia Ext/CAAES Newswire (2004)

“Edible Flowers,”  University of Minnesota Extension

“The Genus Agastache as Bee Forage: An Analysis of Reader Returns,” Iowa State University Digital Repository (George S. Ayers and Mark P. Widrlechner,  1994)

“Some Native Seeds Can Be Planted in the Spring,”Cornell Univ. Ext. (Blog, 2021)

“Agastaches for the Rock Garden,”Rock Garden Quarterly (Richard Dufresne, Summer 1999, p. 185)