Anise hyssop and its relatives offer scent, color, taste, and splendor in the garden.
I first encountered anise hyssop when I was a beekeeper. The attributes of Agastache foeniculum were legend in beekeeping circles: it was rumored to be so rich in pollen that bees would visit no other plant while it was in bloom. Perhaps that’s a bit exaggerated, but honeybees are
extremely attentive during the lengthy bloom period. Honey produced from the plant is of good quality, light in color, and slightly minty in taste.
My beekeeping days were more than twenty years ago—I quit as I found the bees liked me better than I them—but my fascination with the genus has never faded. I am always ready to show garden visitors my stately anise hyssop plant covered in bloom and bee from midsummer to the first frosts of fall. And if they are not familiar with this American native, I crush a leaf beneath their noses to release such a strong anise aroma that the experience is not soon forgotten.
At the time of my introduction to agastaches, there were only two species commercially available—anise hyssop and an Asian relative known as Korean mint (A. rugosa). Today, there are many species and showy hybrids offered by local and mail-order nurseries. Herb growers and perennial gardeners alike are discovering the immense versatility of this genus in complementing and enhancing the garden.
The genus name Agastache (I pronounce it ag-uh-STAH-kee; you pronounce it however you like) is derived from the Greek words agan, meaning “very much”, and stachys, meaning “spike”, and refers to the abundance of terminal flower spikes that bedeck the plant through much of the growing season. The genus belongs to the Lamiaceae (Labiatae), or mint family, and has squarish stems with opposite, serrated leaves and a creeping rootstock much like that of mints but without the same invasiveness. In fact, pulegone and menthone—two mint-scented chemicals—are common constituents of the essential oil of most of the twenty to thirty species in the genus. Like their mint cousins, agastaches die back in the late fall and go dormant until spring.
The flowers vary from 1/4 to 11/2 inches long and are profuse along terminal spikes that range from an inch to as much as 24 inches long depending on species. The color spectrum includes the deep mauves, magenta, white, and greenish yellows of our native species to even more vivid reds, apricots, and hot pinks in the newer hybrids.
In my Zone 8 garden, agastaches are dependable, aromatic upright perennials that when established are remarkably drought-tolerant. Their only pests here are two-spotted cucumber beetles, which nibble a bit on the foliage and occasionally congregate on the flower spikes. If grown in the greenhouse, agastaches are susceptible to green aphid. Surprisingly, slugs don’t seem to pay them much mind, possibly because of the strongly aromatic foliage. One reference mentioned powdery mildew as a problem in climates with hot, dry summers, but here I have seen it only once, on the species A. barberi.
Most species of Agastache come readily from seed or can be divided early in the spring. A. foeniculum and A. rugosa have bloomed for me the first year from seed. I propagate A. cana, A. barberi, and certain hybrids from stem cuttings either in the spring or early fall to maintain the genetic line, although in the greenhouse some of them occasionally have self-sown. The Mexican giant hyssop (A. mexicana) shows wild variation in color and foliage fragrance (sometimes lacking any scent) among seed-grown plants. I suspect that most seed is collected wild from various altitudes and microclimates yet is mixed together in the same bag to sell. So it’s important when buying a plant of this species to make sure it has the fragrance or flower color you want. (At one nursery, I found three distinctively different plants from the same seed lot. I purchased one form that had excellent anise-scented foliage.)
I have grown all of the following agastaches primarily in a sheltered, full-sun exposure on a south-facing site; most have survived to at least 15°F and some to 5°F or lower. The variability in winterhardiness depends on soil, drainage, snow cover, whether the plant is in a raised bed, whether it is established or newly planted, and other factors. When I mail-order a plant, I assume that the catalog’s hardiness suggestion is based on firsthand experience.
Agastaches are highly ornamental plants that deserve a greater recognition and presence in the landscape, not only for the novel range of colors that they introduce into the herb garden but also for their extended bloom season at a time when much of the garden’s glory is beginning to fade. These are some of my favorites.
The best known of the agastaches is anise hyssop, named for the exceptional anise scent and flavor of its foliage. Other common names include blue giant hyssop, fennel giant hyssop, and fragrant giant hyssop. I find it interesting that all the common names refer to another plant, hyssop (Hyssopus officinalis), a Mediterranean herb with needlelike aromatic foliage that is nothing like that of the agastaches. However, the individual tubular flowers of both herbs are similar in having two pairs of protruding stamens, which may explain the association. The species name, foeniculum, means “fennel”, another herb that smells aniselike.
Anise hyssop becomes a rather bushy 3- to 5-foot specimen. It is attractive to both bees and butterflies when it is covered with 3- to 4-inch terminal spikes of 1/4-inch dusky blue-violet flowers. It is native to north-central North America, hardy in zones 3 to 8, and happy in just about any soil. It prefers light shade when grown in hot climates, but full sun otherwise.
The leaves and flowers may garnish fruit cups, iced beverages, or any other food to which you’d like to impart an anise flavor; they make a good herbal tea with a strong licorice flavor. Sprinkle the little individual flowers on a salad for a visual and tasty accent.
The dried flowers and leaves are used to add bulk and scent to potpourri mixes. The fresh flowers hold up well in arrangements, and the dried seed heads are a good addition to dried arrangements. The dried spikes add interest to the winter landscape, too, and several species of birds visit them to pick out the seeds. Native Americans used the leaves as a sweetener and in beverage teas. A decoction made from the root was used to treat coughs and other respiratory ailments.
The new foliage in spring has a purplish cast that serves as an excellent foil for white- or pale yellow-flowered companions or to echo the color of other purple-leaved plants. The foliage is the largest of any of the agastaches that I grow and a medium-textured element in the garden scheme. Place this plant in the middle or back of the border.
A. f. ‘Alba’, sometimes called ‘Alabaster’, is very similar to the species but has white terminal spikes. The foliage never develops the purplish cast of the species, and it tends to be lighter green overall and not quite as bushy. The plant is perfectly hardy and grows to 3 or 4 feet, or slightly shorter than its purple counterpart. It would be a good plant for a white garden. The white anise hyssop comes true from seed, is easily propagated, and often self-sows.
Korean mint, or wrinkled giant hyssop (rugosa means “wrinkled” in Latin), is native to east Asia. In my garden, it is a denser, smaller version of anise hyssop; its 1/4-inch purple-blue flowers have a touch of rose in the center of the flower. It begins blooming a few weeks later than A. foeniculum, sometime in August here. It is hardy to Zone 8 and somewhat short-lived, but it does self-sow.
The smell and taste are less like anise and more like mint. The leaves make a refreshing herbal tea and can substitute for true mint in flavoring dishes. In China, where it is known as huoxiang, it is used to treat stomach disorders, headache, fever, and heart problems, among other complaints.
These two agastaches were the extent of my experience with the genus until about three years ago, when I discovered the hot-colored hybrids and species.
Mosquito plant, also called Rio Grande anise hyssop, is native to New Mexico and western Texas. It is less vigorous, growing only 2 to 3 feet tall. It has short, blunt terminal spikes to 12 inches long of deep rosy-purple inch-long flowers starting in early summer. The grayish leaves (cana means gray) have a good, minty fragrance that is reputed to repel mosquitoes when the leaves are rubbed on the forearms. (My wife, who is far more alluring than I, tried this and swears that a mosquito landed on her arm and immediately took off again.) The plant grows in any well-drained soil in full sun. It is hardy here in Zone 8 and may tolerate colder climates. The species is not common in the trade because it is difficult to propagate. It has never produced seed for me, so I rely on softwood cuttings to increase my stock.
The Mexican giant hyssops comprise several forms that hybridize naturally. As I mentioned above, the seed from different forms is apparently mixed before it is sold, giving rise to a hodgepodge of seedlings. I would like to be able to buy seed unmixed and labeled as to collecting locale, elevation, or form. All of the varieties have slender, upright stems with light green foliage and long flower spikes. Most flowers are clear pink to pink with a purplish cast. I consider the Mexican giant hyssops to be tender perennials and pamper them accordingly. I treat them as annual color spots on the assumption that they will perish when winter comes. All are exceedingly attractive to butterflies—particularly the yellow swallowtails and Oregon monarchs—and any hummingbirds that happen to pass by.
My favorite among the Mexican giant hyssops is A. m. ‘Toronjil Morado’, or giant Mexican lemon hyssop. (Toronjil morado means “purple balm” in Spanish.) The exquisite 11/2-inch-long, tubular fuchsia-pink blossoms appear densely on 18- to 24-inch spikes, and they taste divine. The entire plant has a lemon scent that rivals lemon verbena’s. Unlike its northern cousins, new flowers keep opening through the season until the first frosts. When I first planted this variety, I felt as if I were in the middle of Jack and the Bean Stalk: it just grew and grew. Planted in filtered light, it easily reached 7 feet tall and eventually became susceptible to wind damage. I recommend either staking it in a shaded exposure or finding a sheltered spot for it. I later placed a plant in full sun, where it attained a stately height of 6 feet. A very showy plant for the back of the border, giant Mexican lemon hyssop provides much-needed bloom from late summer to fall as well as a steady nectar source for butterflies and hummingbirds.
Arizona giant pink anise hyssop is one of the hardier agastaches, surviving into Zone 5. It is native to Arizona and New Mexico and has some of the most beautiful flowers of the genus. Its spikes of 11/2-inch-long dusky pink flowers start in midsummer and increase in number as the season progresses. Although the flowers have no taste, the scent of the foliage is reminiscent of catmint. A robust plant growing to about 31/2 feet tall, it prefers full sun with good drainage. This is the only species I’ve grown that has ever been afflicted with powdery mildew.
Tutti-Frutti Mexican anise hyssop, a hybrid of two of my favorite agastaches, features striking 18-inch flower spikes packed with 11/2-inch-long raspberry purple tubular flowers. The flowers are quite tasty and very colorful in a flower salad. Like the foliage, the flowers blend mint flavor with a suggestion of citrus. My potted plant grows only 3 to 4 feet tall, although catalogs describe it as reaching 5 feet in sun, more in half sun. Unfortunately, the hybrid lacks winterhardiness, so I recommend that it not be exposed to temperatures below about 25°F.
Aptly named Apricot Sunrise, this choice hybrid features bright, showy, burnt-orange flowers packed tightly in spikes up to 18 inches long. Each flower is 11/2 inches long and a real showstopper for a hummingbird’s flitty temperament. The plant’s height is modest, reaching only 2 to 3 feet. The foliage is green with a distinctive grayish cast. Its slight fragrance resembles that of catmint. This is a good middle-of-the-border plant, although the color may be a challenge to fit into the general scheme of things as it really stands out among the more subdued colors of the herb garden.
If you are too timid to try Apricot Sunrise, the orange-flowered anise hyssop (A. coccinea) pales in comparison but is still lovely. Although its flowers are sparser than those of Apricot Sunrise, they are less garish and may fit more easily into a garden’s color scheme. The foliage of this species is glossy green and serrated. Some say it’s scented, too, but I’ve never noticed; I’ve never gotten past the beauty of the flowers.
This brilliant hybrid has 18-inch dense spikes of 11/2-inch dusky pink tubular flowers on 3- to 4-foot-tall stalks. Initially, the flowers have an orange blush, but this later turns to a deep pink that is slightly lighter than that of A. barberi. The foliage is a good green sometimes marked with a flush of purple, but it has no scent. Pink Panther is hardy to Zone 7. This plant is just as showy as giant Mexican lemon hyssop and only a bit smaller in stature.
Firebird giant anise hyssop is reported to reach 4 feet in height, but mine has never surpassed 2 feet. Thanks to its parentage, the 18-inch flower spikes have 11/4-inch orange-salmon flowers that mature to a somber red. The leaves have a distinct minty fragrance. Firebird has a superior growth habit and is easy to propagate from cuttings. Though it is said to be hardy to Zone 6, it is one of the few agastache hybrids I’ve grown that has died over the winter here in Zone 8.
I grow agastache species and hybrids mostly for their outstanding range of flower color, long blooming period, and undisputed attraction for butterflies and hummingbirds. They are excellent design plants, exhibiting a strong vertical accent with a medium to coarse foliage texture. Their foliage is a good foil for other herb plants. I take great delight in introducing their rare apricot and hot pink colors into the traditional classic herb garden, where bee balms once reigned unchallenged for spectacular color and showy flowers.
They are among the most gratifying herbs I grow. I can pluck any one of the flowers, pop it in my mouth, and discover perhaps an initial citron flavor followed swiftly by a drop of sweetness. I hand one to a garden visitor to sample, and as I watch the expression of wonder that follows, I know I have won over another convert to the giant hyssop cult!
Andy Van Hevelingen owns and operates an herb nursery in Newberg, Oregon.
Each of the following mail-order nurseries carries a selection of agastaches.
• Canyon Creek Nursery, 3527 Dry Creek Rd., Oroville, CA 95965. Catalog $2. Plants.
• The Flowery Branch, PO Box 1330, Flowery Branch, GA 30542. Catalog $2. Seeds.
• Goodwin Creek Gardens, PO Box 83, Williams, OR 97544. Catalog $1. Seeds and plants.
• Sandy Mush Herb Nursery, 316 Surrett Cove Rd., Leicester, NC 28748-9622. Catalog $4. Plants.
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