Anise hyssop, Agastache foeniculum, is a short-lived, edible herbaceous perennial in the Lamiaceae, or mint family. It’s a native plant suited to gardens in USDA Hardiness Zones 4 to 9. Long used in culinary and medicinal applications, its erect stature and spikes of lavender blossoms make a striking statement in the garden.
I. Appearance and Characteristics
Agastache foeniculum (syn. Agastache anethiodora (Nutt.) Britton), commonly called anise hyssop, blue giant hyssop, Fragrant giant hyssop, or the lavender giant hyssop, is a species of perennial plant in the mint family, (Lamiaceae). This plant is native to much of north-central and northern North America. It is tolerant of deer and drought, and is visited by many pollinators.
This species grows from 2–4 feet (61–122 centimetres) tall and 1 ft (30 cm) wide, in a clump-like, upright shape, with flowers appearing in showy verticillas, or false whorls, and occasionally branching at the apex. The leaves have an oval, toothed shape with a white tint underneath. The plant blooms in June to September with bright lavender flowers that become more colorful near the tip. One plant may produce upwards of 90,000 individual flowers. The root system produces a taproot.
A. foeniculum can be confused with A. rugosa and A. scrophulariifolia. Anise hyssop is in the same family as hyssop (the mint family Lamiaceae), but they are not closely related. Hyssop (Hyssopus) is a genus of about 10–12 species of herbaceous or semi-woody plants native from the east Mediterranean to central Asia.
The species is tolerant of deer and drought, and attracts various potential pollinators, including hummingbirds, butterflies, bumblebees, honey bees, carpenter bees, and night flying moths. Bees make a light fragrant honey from the flower’s nectar.
II. How to Grow and Care
Sunlight
Anise Hyssop prefers full sun. It may grow in partial shade but will get lanky without enough sunlight.
Watering
Water newly planted Anise Hyssop weekly, if there is no rainfall, for the first four weeks. Water slowly and deeply, welcoming deep, spreading roots. Once plants are established, cease watering. Being drought tolerant, they are very easy to grow and care for.
Soil
Anise Hyssop will do best when planted in soil that is fertile and well-drained—some combination of sand, loam, chalk, or clay typically works well. Do your best to avoid soil that is too heavy, which can make it difficult for the roots to get established and may lead to root rot. Additionally, your soil should have a pH that is as close to neutral as possible—you can amend it with lime if it’s too acidic.
Fertilizing
Feed your Anise Hyssop in early spring every other year with about a bucket of organic compost that has been sprinkled around the base of the plant. Make sure to target the roots and leave a couple of inches of soil space between the compost and the plant’s main stem.
Pruning
Anise Hyssop is a fairly independent plant and won’t need much attention once it has established itself in your landscape. Occasional pruning can help encourage the plant to bloom and keep the plant looking its best. Pruning is best done in early spring, using a pair of clean pruning shears. Cut back up to one-third of the plant to encourage more full, bushy growth. Remove any dead plant material just above a promising bud node.
Propagation
There are three ways to propagate anise hyssop. Let’s look at each method:
- From Seed
A. foeniculum seeds germinate well after exposure to cold and moist conditions. This process is called cold stratification.
The best way to start seeds is to sow them directly into the garden in early fall, so they can experience natural cold stratification during the winter months.
Unlike many seeds, those of A. foeniculum need light to germinate. Moisten the soil and sprinkle them on top about three inches apart, then gently press them down.
Keep the soil moist over the winter months, watering just before it completely dries out.
In the spring, the seeds will sprout.
When the seedlings have at least two sets of true leaves and are fairly sturdy, thin them to a distance of one and a half to three feet apart, depending upon the mature width of the variety you have sown.
You can check your seed packet to determine the mature dimensions. Expect blooms in the first year after sowing.
Alternatively, you can manually replicate the cold stratification process.
To do this, store seeds on top of a layer of moist potting medium or sand, and place in the fridge for about a month before sowing.
To get a jump-start on the growing season, start seeds indoors six to eight weeks before the last average frost date in your area.
Transplant seedlings to the garden when they have at least two sets of true leaves and all danger of frost has passed.
Or, direct sow cold-stratified seeds outdoors after the last average frost date has passed, for flowers in the second year.
- By Division
In early spring when the first signs of new growth appear, or in late fall as winter dormancy begins, you can divide existing clumps to make new ones.
This is an excellent way to replicate hybrid varieties, as the seeds from hybrids do not produce the exact traits of the parent plants. In addition, some are infertile and produce no seeds at all.
You’ll need a clean, sharp shovel and some elbow grease. Please see our guide to dividing perennials for full instructions.
- Stem Cuttings
Another way to begin is with semi-soft stem cuttings. This method is also a good way to clone hybrids.
In early summer, after the new, soft growth of spring has begun to firm up and before budding, use clean, sharp pruning shears to cut the tip of a growing stem to a length of about six inches.
Strip the bottom leaves to reveal a bare stem that is two to three inches long. Dip the stem into powdered rooting hormone and place it in a container filled with your choice of potting medium to a depth of at least two inches.
Place the stem cutting in a bright location, out of direct sunlight. Water before the potting medium completely dries out to maintain even moisture, but never allow it to become soggy.
At first the stem will wilt, but it will soon perk up. When new growth is evident, you’ll know it has grown roots.
Transplant the rooted cutting to the garden. It will wilt again, at first, but will rebound in time. Maintain even moisture while the young plant becomes established.
Pests and Diseases
Be mindful that crown/root rot may occur in poorly drained soils. Keep an eye out for rust, powdery mildew, and leaf spots. Despite these potential issues, Anise Hyssop is quite hardy, being deer resistant and a generally vigorous perennial.
III. Varieties
There are many types of Agastache, the genus representing 30 different plants, each with varied flower colors, heights, foliage, aroma, and hardiness. Bloom colors of various hybrid varieties range from pink to creamy white, powder blue to red-violet. Foliage can be dark green to lime green. Here are some of the most popular varieties:
- ‘Alabaster’ is a hybrid with creamy-white flowers. The foliage is lighter green than most other hybrids. Plants grow about 3 feet tall and not as bushy as some other kinds of anise hyssop.
- ‘Black Adder’ has dark buds and red-violet flowers. It grows less quickly and robustly than other species.
- ‘Blue Blazes’ is a tall hybrid of A. foeniculum and Agastache ‘Desert Sunrise.’ Hardy to USDA Zone 5, this hybrid has pinkish calyxes and lavender purple blooms that seem to glow in the sunlight.
- ‘Blue Fortune’ is a sterile hybrid of A. foeniculum and A. rugosa. Flower spikes are especially thick and come in a shade of powder blue. Leaves are large and deep green. Peak bloom is in midsummer. Flowers last a particularly long while because they set no seeds. Plants grow 3 feet tall.
- ‘Blue Fountain’/’Blue Spike’ is another variety of anise hyssop to consider. This one has clear blue flowers.
- ‘Golden Jubiliee’ has lasting, powder blue flowers, contrasting pleasingly with its chartreuse foliage. This tough plant thrives even in high heat and humidity.
- ‘Liquorice Blue’ has violet-blue flowers with reddish-purple calyxes.
- ‘Purple Haze’ produces flowers spikes that are narrower than many other varieties of anise hyssop. Because they are so narrow, spikes do not attract as many large native bees, but they may be attractive to smaller pollinators that are able to fit inside.
- ‘Red Fortune’ has pink flowers. This hybrid does not attract as many pollinators.
- ‘Snow Spike’ (also known as ‘Album’) produces white flowers and grows 3 feet tall.
IV. Uses and Benefits
Stemming from a long history of medicinal use by Native Americans, Anise Hyssop is a versatile, aromatic, culinary, healing herb. It has many uses in the garden and the kitchen. The flowers’ nectar attracts bees, butterflies, and hummingbirds. Meanwhile, birds tend to eat any seeds left on the stalks toward the end of fall. Both flowers and leaves offer an intense licorice scent and taste.
Crumble aromatic leaves in salads, use them to make jellies, steep them in herbal tea (as the Cheyenne tribe has done to relieve depression), or incorporate them in potpourris. Sprinkle seeds in cookie, muffin, or biscotti mix; dried leaves can be used as a seed substitute for similar licorice flavor. Fresh flowers make interesting additions to bouquets. Hang these blooming spikes upside down or let them dry naturally on the plant to add to dried floral arrangements.
Find Where to Buy the Best Anise Hyssop (Agastache foeniculum)
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