Agastache might be one of the toughest plants you’ll come across, although you wouldn’t guess it from its colorful, graceful flower spires and incredibly scented leaves.
Despite its pretty appearance, agastache thrives in poor soil and remains unaffected by deer, rabbits, and many other common garden pests. It also has the bonus of being edible and a favored plant by herbalists for many years.
Here’s more about why you need this plant in your garden, plus a detailed guide on how to grow and care for agastache.
What Is Agastache?
Agastache (Agastache spp.) is what’s known as a tender or short-lived perennial. In colder climates, it may only last 1-3 years, but it self-sows readily and will keep popping up for many, many years.
In warmer climates, agastache is a more consistent perennial. It can be grown in USDA hardiness zones 5-9 with some cultivars being hardy down to zone 4.
To make matters confusing, agastache goes by many other names, including hyssop, anise hyssop, giant hyssop, and hummingbird mint. It is, however, a completely different plant than both hyssop (Hyssopus officinalis) and anise (Pimpinella anisum), although it does belong to the mint family.
Almost all species of agastache are native to North America. Blue- and purple-flowering varieties tend to be native to the eastern and midwestern U.S., and the orange- and red-flowering ones tend to originate from the southwestern U.S. and Mexico.
Agastache is something of an underrated perennial like native wildflowers often are. However, it’s a highly ornamental plant while also being incredibly low maintenance and beneficial for pollinators.
On average, plants grow about 2-4 feet tall, although some compact cultivars only get about a foot tall. They bloom with colorful flower spikes from early summer all the way to fall.
Leaves tend to be medium green to blue-green and have a sweet anise smell with hints of mint. Certain cultivars have foliage with a more fruity scent, and all varieties are edible.
What Makes Agastache a Great Plant
Agastache is an incredibly low maintenance plant. It’s drought tolerant and will thrive in dry areas of your garden. This makes it a perfect choice for a low to no water garden (also known as a xeriscape).
Few pests or diseases bother agastache, and it’s resistant to deer and rabbits. It actually grows better in poor soil rather than fertile soil.
The bright, tubular flowers are very attractive to pollinators and hummingbirds (hence the name hummingbird mint). You’re likely to see butterflies and bees flocking to your plants when they bloom, and songbirds like goldfinches will feast on the seeds later.
Another benefit of growing agastache is that you can use the leaves to make a fragrant herbal tea. The flowers are also edible and look great in cut flower arrangements as well.
Goldfinches especially love the seeds of agastache. Leave some flowers on in late summer and fall so that they have a chance to fill up before winter.
Top Types and Cultivars of Agastache
There are a few species of agastache that are most commonly grown in the garden as well as many popular hybrid cultivars. Plants range in size from fairly compact to 4 feet tall with varieties that fit both warm and cool color schemes.
Here are some top choices to consider:
- Anise Hyssop (Agastache foeniculum)– Anise hyssop is a popular species and the most commonly grown as an herb garden plant. The leaves smell like licorice and can be used to make various herbal remedies. Flowers are lavender and grow in spikes that get up to 4 feet tall. Plants are mostly hardy in zones 6-10.
- Korean Hyssop (A. rugosa)– Korean hyssop is similar to anise hyssop but only grows about 2 feet tall. The flowers are purple-blue, and plants are hardy in zones 5-9.
- Texas Hummingbird Mint (A. cana)– Ironically, this species is native to New Mexico. Plants grow about 3 feet tall and bloom with rose-pink flowers. Hardy in zones 5-9.
- Sunset Hyssop (A. rupestris)– Another Southwest native, sunset hyssop blooms orange and has gray-green foliage. Hardy in zones 4-9.
- ‘Blue Fortune’– A cross between A. foeniculum and A. rugosa, this cultivar has purplish blue flowers and grows about 3 feet tall. Tolerates both wet and dry conditions well.
- ‘Little Adder’– A more compact plant, this cultivar grows only about 15-18 inches tall. Flowers are lavender-blue and bloom very abundantly.
- ‘Golden Jubilee’– This cultivar has unique golden-green foliage and purple-blue flowers that bloom from midsummer to fall. Grows 2-3 feet tall.
- ‘Summer Sunset’– This cultivar blooms with sunset shades of orange. It definitely brightens up the garden and blooms strong through the heat of summer. Grows 1-2 feet tall.
Orange cultivars can really brighten up your garden and mix well with red and yellow varieties. They also tend to be a little more cold hardy than some of the blue and purple cultivars.
- ‘Desert Sunrise’– A beautiful cross between A. cana and A. rupestris, this cultivar will bloom for months with tall pink and orange flower spikes. Grows up to 4 feet tall.
- ‘Tutti Frutti’– This popular cultivar has gray-green leaves and raspberry-pink flowers. It also has uniquely fruit-scented foliage instead of the typical anise-scented leaves. Grows 2-3 feet tall and should be grown as an annual in regions colder than zone 7.
- ‘Red Happiness’– Plants have vibrant red flowers that are extremely attractive to hummingbirds. This cultivar is very cold hardy and grows about 2 ½ feet tall.
- ‘Kudos Yellow’– Sunshiny yellow flowers bloom on this cultivar from summer to fall. Plants grow about 2 feet tall.
How to Grow Agastache from Seed
You can likely find a good variety of agastache for sale locally or online, but this is also an easy perennial to grow from seed. Buy seeds for the specific cultivar(s) you want to grow, since they won’t necessarily come true from seed if harvested from a friend’s garden.
Growing from Seed Indoors
To get a headstart on the growing season, you can start agastache seeds indoors 4-6 weeks before your last average frost date in the spring.
Starting your plants from seed indoors will give them a headstart, although they still might not flower the first growing season. Put your plants out in the garden after the last frost has passed.
Here’s what you’ll need:
- Agastache seeds
- Seed starting tray or cell packs
- Soilless seed starting mix
- Grow lights (optional)
- Plastic domes (optional)
- Small fan (optional)
Like many other perennials, agastache seeds need to go through a process called stratification in order to help them germinate. This just means that you’re going to mimic the cold temperatures of winter to weaken the seed coat so water can get through.
Do this by getting your soilless growing medium damp and placing the seeds on top of it. If you have a large refrigerator, you can go ahead and put the growing mix and seeds in a tray. Otherwise, place them both in a plastic bag to save on space.
Make sure your seeds and soil are covered with plastic, then put them in your refrigerator for a month. You can check on them halfway through to make sure the soil is still damp.
Remove your seeds after the month is up. If you didn’t plant them in your trays, go ahead and do that now by placing seeds on top of the soil. Press the seeds in, but don’t cover them at all (they need light to germinate).
Cover your trays with plastic domes to keep moisture in, and set them under grow lights or by a sunny window. Seeds should germinate in about 2 weeks but can take up to a month.
Keeping your seedlings well-watered as they grow is important, but you don’t want to overdo it. Water just before the soil dries out, and run a fan every so often to help prevent fungal diseases like damping off.
Once your seedlings sprout, remove the plastic domes and keep them under grow lights. Water as needed to keep the soil from drying out and run a fan a few times a day for good air circulation.
When your seedlings are about 4 inches tall, you can harden them off by taking them outside during the day and bringing them back in at night. After a week of doing this, they are ready to go in your garden!
Growing from Seed Outdoors
You can also skip a few steps by directly sowing your agastache seeds outdoors in the spring. Just keep in mind that directly sown plants will take longer to bloom than ones started indoors.
Seeds should be planted after the danger of frost has passed in the spring. Get them ready a month ahead of time by putting them through the cold stratification process explained above.
After your last frost date, choose the area where you want to plant your seeds and clear it of weeds and debris. Rake the surface smooth to give yourself a place to sow seeds. Then, scatter your seeds on top of the soil and press them in gently.
Water the area where you planted seeds and keep it from drying out while they germinate. Germination should happen in 2-4 weeks.
Planting seeds outdoors is easier but plants will be behind those started early indoors. For a really hands-off approach, sow seeds in fall and let them sprout on their own in the spring.
Another easier option for directly sowing seeds is to do it in the fall. Winter will do the stratification process for you, and the seeds will sprout exactly on time in the spring.
All you need to do is prepare an area of your garden in mid-fall and sow your seeds on the soil’s surface. Press them into the soil, and you’re done! You don’t even need to water because nature will do that for you over the coming months.
Whichever way you planted them, thin your seedlings to their correct spacing once they develop two sets of true leaves.
Planting Tips + Growing Conditions
When to Plant
Whether you grew your own transplants or bought some at the store, they can go in your garden after all danger of frost has passed in the spring.
If you don’t get them out right away, there’s still time! Agastache seedlings can be planted up to about early summer or midsummer in cooler regions. If you wait longer than this, they may struggle to get established because of hot, dry conditions.
Where to Plant
As a general rule, agastache loves sunlight. Plant it in a full sun or mostly sunny spot in your garden. In warmer climates, agastache will tolerate partial shade (especially afternoon shade) but may not flower as well.
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Agastache will grow just fine in poor soil and will actually become floppy if it gets overfertilized. The most important soil requirement is that it be well-drained, since plants don’t like wet conditions or soggy feet.
Mixing in a good amount of compost before you plant is a great way to improve soil drainage and provide your plants with nutrients without overdoing it.
Spacing will depend somewhat on the variety you’re planting, but most agastache plants should be spaced 15-18 inches apart.
How to Plant Agastache
Agastache is easy to plant. Once you have your garden area picked out, clear a space for your plants by weeding and getting rid of rocks and debris. You can add any needed soil amendments at this time as well.
Dig holes for your plants that are just as deep as the root ball and a few inches wider. Place seedlings so that the top of the root ball is just level with the soil.
Fill back in around each seedling with soil, and firm the top of the soil with your hands once you’re finished planting. Make sure you water your newly planted seedlings well and deeply enough to reach the bottom roots.
Agastache Care and Maintenance
Until your plants get established, you’ll need to keep watering them whenever the weather turns dry. Be sure to water them deeply before the soil completely dries out.
Most agastache plants thrive on neglect. The worst thing you can do for them is to plant them in poorly drained soil, which they really dislike.
Once plants are mature, they will be drought tolerant and can go weeks without any supplemental water. You’ll only need to water them during very severe drought periods.
Many gardeners favor using mulch to cut down on weeds, but it’s not the best choice for agastache, especially if you live somewhere with wet or humid conditions. If you really do want to mulch, choose something lightweight and non-absorbent like pine needles or gravel.
Agastache rarely needs fertilized and too much fertilizer will actually harm your plants. You can, however, add a layer of compost around your plants every year or two.
You can deadhead or trim back your agastache with hand pruners after it finishes blooming to promote new growth and more flowers, but this is optional. In fact, you should leave some seed heads on at the end of summer to feed local birds.
The stems of agastache will eventually turn brown and die, but do not cut them back in the fall unless you live in a very mild climate. Cut the dead sections back right above the new foliage in mid spring.
If you live in a borderline zone, apply a good layer of mulch before the cold of winter hits to help protect your plants. Use something like gravel in wet regions. Remove the mulch early in spring.
If you have pine trees nearby, the needles make a surprisingly good mulch. They won’t absorb water, which can lead to your agastache rotting, but still offer winter protection and weed control.
Agastache likes to self-sow, so be prepared to pull out unwanted seedlings in the spring. Be sure to leave a few to transplant to other areas in your garden!
Pests and Problems
Agastache rarely has pest or disease problems, which is one of the things that makes it great for a low maintenance landscape.
If you plant agastache in heavy clay or in a poorly drained area, it can develop rot and other fungal diseases. Prevention is the best method, so make sure plants are properly spaced, and add sand or another soil amendment to improve drainage.
Uses in the Garden + Good Companions
Agastache is an excellent plant for pollinator gardens, naturalized areas, butterfly gardens, and wildflower meadows. As a native plant, it provides both nectar and food for a lot of local wildlife.
Some of the smaller varieties can be grown in large pots as part of a container garden. All varieties would also be at home in a cut flower garden, since they look lovely in flower arrangements.
Although it can be grown as either an annual or a perennial, agastache mixes especially well with other perennial plants. Here are a few of the top ones to combine with agastache:
- Salvias (garden sage)
- Bee balm
- Ornamental grasses
- Black-eyed Susan
- Russian sage
- Joe Pye weed
As you can see, there are so many reasons to add the versatile and tough agastache to your garden. Once you plant a few, you might find yourself hooked. Local bees, butterflies, hummingbirds, and songbirds will also appreciate your efforts!