|Anise Hyssop (Agastache foeniculum): in full bloom in August|
Summer’s in full swing by August – at least here on Colorado’s Western Slope. Mother Nature’s Montrose Garden is transitioning from the ‘mostly yellow and orange’ of late spring to a combination of pinks, purples and yellows. Of course, the pollinators are busy and in need of pollen and nectar. Which brings us to our Plant of the Month, Agastache foeniculum. The scientific name is pronounced: ag-us-TAH-kee fen-IK-yoo-lum.
Agastache foeniculum is known by a number of common names including Blue Giant Hyssop, Anise Hyssop, Lavender Hyssop, Licorice mint, Blue Giant-hyssop and Fragrant Giant Hyssop. It is native from the Pacific Northwest to the upper Midwest. It grows in mountain meadows and forest openings (from about 6500 to 8000 ft.) on the Front Range in Colorado.  Fortunately, it also grows well in home gardens.
Despite its common name, Blue Giant Hyssop is not a true hyssop (the true hyssops – genus Hyssopus - are herbal plants from Europe, the Middle East and Central Asia). But both the true Hyssops and Agastache foeniculum are members of the Mint family (Lamiaceae). In general, this family is easy to grow and has attractive flowers and foliage. Many members are also fragrant, and the family is known for both its culinary and medicinal uses. But what many gardeners don’t realize is the importance of this family for bee pollinators, especially for long-tongued bees (like the Bumble Bees) and also for butterflies.
|Anise Hyssop (Agastache foeniculum):first year|
|Anise Hyssop (Agastache foeniculum): second year|
Anise Hyssop is an upright, bunching, herbaceous perennial plant (above). It grows 2-4 ft (0.6 – 1.3 meters) tall and 2-3 ft. wide. It grows from a shallow taproot and has short rhizomes (underground stems). The clumps grow slowly, enlarging every year.
|Anise Hyssop (Agastache foeniculum): foliage|
The foliage of Blue Giant Hyssop is medium to dark green and very neat appearing. The stems are square (typical of Mint family) and sturdy, but not coarse-looking. Stems usually remain upright without staking (unless there’s a serious windstorm, of course). The leaves are opposite, oval or heart-shaped and toothed, with a slightly white tinge beneath (due to plant hairs). The entire foliage gives off a lemony or anise-flavored scent when rubbed or crushed. In fact, the leaves and flowers can be used as a flavoring (more below).
|Anise Hyssop (Agastache foeniculum): flowering plant|
Anise Hyssop blooms from early summer to early fall, depending on local conditions. It can start to bloom from mid- to late-July in our Montrose garden. And the bloom period lasts 6-8 weeks, or even a little longer. The plant is very attractive in bloom (above) – always provokes comment from garden visitors.
|Anise Hyssop (Agastache foeniculum): flowers|
The individual flowers are small, pale lavender or blue and arranged in densely-packed terminal spikes. The flowers are typical for the Mint family, tubular with two lobed lips and four protruding stamens (above). The flowers have no scent. But the masses of small flowers are very attractive to bees, particularly Bumbles Bees and European Honey Bees, but also Halictid bees, digger bees, leaf-cutting bees and masked bees. The flowers also attract butterflies, moths and hummingbirds.
|Anise Hyssop (Agastache foeniculum): great pollinator plant!|
Blue Giant Hyssop is a great pollinator plant, providing both high-quality nectar and pollen. There is always some pollinator or another at our blooming plants – dawn to dusk. In fact, this plant is often planted specifically for its pollinator habitat value, including in agricultural settings. The small seeds are eaten by seed-eating birds – like finches – in the fall.
|Anise Hyssop (Agastache foeniculum): easy to grow|
Agastache foeniculum is an easy perennial to grow (USDA Zones 3 to 8 or even 10). It thrives in full sun to part-shade, in a wide range of soil textures and pHs (5.8 to about 8). The only real requirement is that the soil have good drainage. So, if you have heavy clay, consider growing it in a large container. Also, forego the heavy mulches; just use a light layer of organic mulch or none at all. And no fertilizer needed, except when grown in containers. Even then, ½ strength does in spring is all that’s needed.
Anise Hyssop is pretty much pest and disease-free, at least in our garden. I suspect slugs and snails might be tempted by new foliage in gardens wetter than ours. Established plants have some drought tolerance. We water them once a week during the hottest part of summer in the drier areas of the garden. They are surprisingly heat and drought tolerant! But they also can take fairly regular water, including overspray from a lawn, as long as the soils drain well.
|Anise Hyssop (Agastache foeniculum): tolerates regular water|
Anise Hyssop is easy to grow from seed, but it does need some cold to germinate well. Seeds are easily collected once the flower spikes turn tan-brown. Simply cut off the stems, invert in a paper bag, and let the seed pods entirely dry. The small seeds will fall out into the bag, ready for planting. Alternatively, just pull apart the flowering spikes and sprinkle onto your prepared seed bed. Or, if you’re really pressed for time, just let Mother Nature spread the seed around for you. This plant re-seeds nicely on bare ground!
|Anise Hyssop (Agastache foeniculum): seedlings|
The easiest way to plant from seed is to sprinkle Agastache foeniculum seeds in a prepared bed in late fall. Alternatively, sow seeds in pots that are kept out of doors. Don’t cover the seeds with medium, as they need light to germinate. If you seed into containers, be sure to keep the medium moist through the winter and early spring. The seedlings are distinctive (see above); they will appear when the soils warm up in spring. If seedlings show up in inopportune places, they are easy to pull. Seedlings can also be transplanted.
|Anise Hyssop (Agastache foeniculum): in mixed perennial bed|
So, how to use Anise Hyssop in the home garden? It is such an attractive perennial, throughout the growing season, that it’s appropriate for many garden situations. We like to plant some around a vegetable garden to attract the pollinators. It is right at home in an herb or medicinal garden (more below). But it is equally appropriate mid-bed or as an accent in a mixed perennial bed. It’s pretty enough to plant in your front yard!
|Anise Hyssop (Agastache foeniculum): lovely with Goldenrods|
We like the late summer contrasts of purple-pink Agastache foeniculum, Verbena stricta (Hoary Vervain), Prairie Ironplant (Vernonia fasciculata), Purple coneflower (Echinacea purpurea), Bee balm (Monarda spp.) and the bright yellows of goldenrods and rabbitbushes (above).
Plant some near a seating area, where you can crush the leaves to release their unique aroma. And be sure to plant enough Anise Hyssop for your culinary uses. The flavor is complex and hard to describe: anise with a hint of lemon and other spices. Anyway, the leaves and flowers make great flavoring agents and have been so used for a long time.
|Anise Hyssop (Agastache foeniculum): use as flavoring agent|
Make refreshing hot or iced tea from fresh or dried leaves. The leaves have their strongest flavor as the flowers begin to turn tan, but the leaves can be picked anytime. Or make a cordial or syrup with the leaves. Flowers can be used to flavor baked goods, salads and other foods. In fact, you’ll be surprised at the number of recipes online. Just search ‘Anise Hyssop recipe’ to find something to your liking. If desired, leaves can be dried (like any mint) for later use.
|Anise Hyssop syrup|
Agastache foeniculum has a long history of medicinal use. Hot tea made from the leaves is good for colds, coughs, congestion and fevers.  Cooled, this infusion was used to sooth lungs sore from coughing and for allergic skin reactions.  A poultice of leaves and stems was traditionally used to treat burns. The scent of Anise hyssop is said to ‘lift one’s mood’ when burned as incense or used in potpourri. At the very least the aroma – in tea, food or potpourri – is very pleasant and refreshing!
|Easy to make tea from Anise Hyssop.|
There are a number of cultivars of Anise hyssop as well as hybrids with other Southwestern native Agastache species and with Korean hyssop (A. rugosa). If your garden needs more color than the straight species, you might look into the cultivars and hybrids. Many of these are also attractive, good pollinator plants and available in the nursery trade (including online). [see ref. 4]
|Agastache 'Blue Blazes': a hybrid of Anise Hyssop (Agastache foeniculum)|
In summary, Agastache foeniculum is a good-looking, easy-to-grow native perennial that does well in many gardens. It is lovely massed or as an accent plant. It brings a long bloom season, whether grown in the ground or in a container. It is an excellent pollinator plant whose complex aroma makes it a good flavoring agent. So, order some seeds (or get some from a friend’s garden) and plant this fall, for a great addition to next year’s garden.
|Anise Hyssop (Agastache foeniculum): a good choice for many gardens|
- Ackerfield, J.: Flora of Colorado. Brit Press, 2015.
For a gardening information sheet see: https://www.slideshare.net/cvadheim/gardening-sheet-agastache-foeniculumpdf
For more pictures of this plant see:
For plant information sheets on other native plants see: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html
We welcome your comments (below). You can also send your questions to: email@example.com