Agastache is a group of hard-working perennials, most of which are heat and drought-tolerant. They are showy and long-blooming plants with spikes of flowers atop tall, herbaceous stalks. The blooms (which come in wonderful shades of blue, purple, pink, red, orange, and white) produce a fragrant nectar that is irresistible to hummingbirds and butterflies. The flowers, depending on species, smell sweet, sometimes with notes of bubblegum, root beer, or floral anise. Their foliage is also fragrant, with scents of licorice and mint.
There are more than 30 species in the agastache group, most native to North America. These are often confused for Hyssopus officinalis, an herbaceous perennial that bears similarities but belongs to a different genus. There's also some debate over how to pronounce the genus. Some Americans prefer to say, "ag-Uh-stash" (like mustache) while others (including the British) prefer, "a-GAH-stah-kee". Whatever you call it, the perennial is a welcome addition to informal landscapes where height, color, and lovely fragrance are desired.
Hyssop Plant Overview
Where to Plant Agastache
Most agastache plants require well-drained soil and full sun, although they will tolerate light shade. Their sweet, herbaceous scent makes them perfect for herb and butterfly gardens—especially since they deter hungry deer and rabbits when placed along the outside edges.
To enjoy the fragrance yourself, plant agastache along walkways and garden borders. The pretty summer bloomer would look beautiful in a cottage garden among the foxgloves, lavender, and roses. Or, could flourish in a prairie garden alongside coneflowers and coreopsis. Agastache plants are also great for xeriscaping and low-water gardens.
How and When to Plant Agastache
Agastache is a carefree plant that returns each year (in zones 4-10) and happily self-seeds once established. If you are planting new seedlings or nursery-grown plants, wait until early spring when the ground is no longer frozen. When you are ready, dig a hole twice the size of the plant’s original pot. Tease apart the roots and place the new plant in the hole. Position the plant so it sits at the same level it did in its former pot. If you are planting more than one plant, space them about 18 to 24 inches apart.
You can also sow agastache seeds directly in the ground in the fall by pressing them about 1/4 inch deep in loosened soil. The seeds will stratify over the winter and should germinate in the following spring.
Agastache Care Tips
Agastache plants are tough perennials that need little care once established. In the right conditions, it will return year after year and bloom all summer long.
Light
Agastache prefers full sun (at least 6 hours a day). It will survive with less exposure (as few as 4 to 6 hours each day) but will not thrive in those conditions. When grown in only partial sun, your agastache may not grow as tall or produce as many flowers.
Soil and Water
Agastache can tolerate almost any soil conditions, including loamy, sandy, clay, and rocky soils. However, it does best with lean, well-draining soils with a low level of nutrients and a soil pH between 6.0 and 8.0. If planted in overly rich soils, agastache can grow floppy and may not develop strong enough roots to return in the spring.
Agastache plants are relatively drought-tolerant once established. (They are, after all, successfully grown in high-desert conditions.) Provide consistently moist soil for your seeds and seedlings, but water mature plants only occasionally—if at all. In most climates, you can get away with a single deep soak every few months even in the height of summer. Do not water agastache when temperatures dip below 50˚ Fahrenheit.
Temperature and Humidity
Agastache can handle high temperatures, which makes it an excellent candidate for the sunniest spots in your yard. The optimal temperature range for agastache is between 65˚ and 75˚ in the daytime and 50˚and 60˚ in the evening. During the winter months (in most regions), the agastache root system will go dormant. This chill period is essential for the stratification of new seeds.
As with the heat, agastache is tolerant of high humidity but fares best in moderate humidity with plenty of air circulation between plants. Some gardeners also find the blue-flowering varieties of agastache to be slightly more tolerant of moist conditions.
Fertilizer
Fertilizer is not necessary with agastache. In fact, it may cause more harm than good. Too much fertilizer (or overly fertile soil) may cause your plants to grow leggy and floppy. Overfertilization could also encourage root rot.
Pruning
Agastache does not require pruning, but there are some steps you can take to help your plants thrive. First, pinch back new growth in early spring to encourage a more lush plant. Next, deadhead spent blossoms (from spring to midsummer) to extend the blooming season. Just avoid deadheading flowers past midsummer as it may cause tender new growth that will not survive the winter.
In the fall, cut your plants back to 4 to 6 inches above the soil. You can also do this in early spring, but be careful not to damage new growth.
Potting and Repotting
Agastache can be grown in containers, but be aware that some types—especially giant hyssops (like Agastache Mexicana) may be too top-heavy for most containers. In early spring, choose a container with ample drainage and a large enough space to accommodate the plant's root system. Fill the container halfway with a well-draining all-purpose potting mix and add your plant. Continue filling the pot and tamping the soil until the plant is secure.
Place the plant in a sunny location and keep the soil evenly moist until your agastache is established. After that, water only when the top 3 inches of soil is dry. Once every 4 to 6 weeks (from spring through summer) feed your potted agastache with a diluted liquid fertilizer. Do not fertilize in the fall and winter. If you have especially cold winters, move your potted agastache to a protected (but not heated) location when temperatures drop below 40˚ Fahrenheit.
Repot your agastache in early spring every 2 to 3 years or when the roots become visible through the drainage holes. You can move it to a larger container (about 1 to 2 inches wider) or divide the root clump into multiple parts and plant each section in a separate pot.
How to Propagate Agastache
Agastache is easily propagated via seed or division. To divide your agastache, wait until spring and carefully dig up your plant. Use a sharp blade or shears to cut the root system into 2 or 3 parts, each with a bit of roots and top growth. Replant the sections approximately 18 to 24 inches apart.
To propagate from seed, start by cold stratifying the seeds in the refrigerator for 1 week about 6 to 8 weeks before the last frost. Place the seeds on the surface of a soil-less growing medium and seal them inside a plastic bag. After stratification, sow the seeds about 1/4 inch deep in a seed-starting mix. Keep the soil warm and evenly moist until seedlings emerge (about 2 to 3 weeks). Keep the seedlings in a sunny spot to continue growing. Once the seedlings are 2 to 3 inches long, harden them off in a sheltered outside area for 1 week and then plant them in the ground. You can also sow agastache seeds directly in the ground in the fall.
Pests and Problems
Agastache plants have few issues with pests, but it's wise to watch out for flea beetles, slugs, and snails.
Powdery mildew and root rot can be an issue for agastache plants. These issues and other fungal diseases are exacerbated by overwatering, overcrowding, and overly moist conditions.
Types of Agastache
There are over 30 types of agastache, but the most commonly found types in the United States are anise hyssop (Agastache Foeniculum), Mexican giant hyssop (Agastache Mexicana), Korean mint (Agastache rugosa), and sunset hyssop (Agastache rupestris).
Anise hyssop
Despite its common name, anise hyssop is neither hyssop nor anise (Pimpinella anisum). Agastache foeniculum bears upright columns of purplish-blue blooms on plants 2-5 feet tall. Arguably the most common type of agastache, anise hyssop grows best in Zones 4-10.
Korean Mint
Korean mint (Agastache rugosa) is a towering agastache that grows 3 to 5 feet tall and 2 feet wide. It features vibrant purple flower stalks—which often bloom the first season after planting—and licorice-scented foliage. Korean mint is hardy in zones 4 through 10 and slightly more tolerant of moisture and humidity than other agastache types.
Sunset hyssop
Agastache rupestris is a common agastache that derives its name from the brilliant mix of red, purple, and orange shades in its blooms. The finely textured foliage can grow to 4 feet tall in zones 4-9.
'Ava' hyssop
Agastache 'Ava' is a hybrid between A. cana and A. barberi. The raspberry-red flower spikes have deeper red calyxes, which remain colorful even after flowers fade. This makes 'Ava' a good choice for dried flowers. Both the foliage and flowers are fragrant. Ava hyssop grows 4-5 feet tall in zones 5-10.
'Blue Fortune' anise hyssop
Agastache foeniculum 'Blue Fortune' has lavender-blue flower spikes on 3-foot-tall plants from July through September in zones 4-10.
'Bolero' hyssop
Agastache 'Bolero' is a compact hybrid with rose-purple bloom spikes throughout the summer. The bronzy gray-green foliage exudes a minty fragrance when crushed. The plant grows just 18 inches tall and wide (when in bloom), making it an excellent choice for container gardens in zones 5-10.
Bubblegum mint
Agastache cana is called bubblegum mint because its gray-green foliage exudes the fragrance of pink bubblegum or licorice. It bears foot-long spikes of purplish-pink blooms throughout the summer on plants that grow 3-4 feet tall. It is also called Texas hummingbird mint because it is native to western Texas and New Mexico and attracts hummingbirds. It's hardy in Zones 5-10, but may need winter protection in Zone 5.
'Golden Jubilee' anise hyssop
Agastache foeniculum 'Golden Jubilee' is a stunning selection that bears chartreuse foliage topped with lavender-purple flower spikes. It is hardy in zones 4-10.
'Heatwave' hyssop
Agastache 'Heatwave' is a hybrid with bright lavender-pink blooms that attract butterflies, hummingbirds, and bees from mid- to late summer when it is in bloom. As its name suggests, it scoffs at heat and humidity. It grows 3 feet tall and wide in zones 5-10.
'Purple Pygmy' hyssop
Agastache cana 'Purple Pygmy' is a compact version of bubblegum mint with rosy purple blooms. The gray-green foliage has a distinct pink-bubblegum fragrance. It is available from seed or as started plants. 'Purple Pygmy' grows 16-24 inches tall in zones 5-10.
'Raspberry Summer' hyssop
Agastache 'Raspberry Summer' has raspberry-pink blooms from the start of summer into fall. These plants are less tolerant of moisture and are more demanding of good drainage. 'Raspberry Summer' hyssop is hardy in zones 6-9.
'Rosita' hummingbird mint
Agastache cana 'Rosita' is a compact form that grows 2 feet tall with dense clusters of deep rose-pink flowers in zones 5-10.
'Sinning' hummingbird mint
Agastache cana 'Sinning' grows to only 18 inches tall. Its lavender-rose tubular flowers appear nearly all summer in zones 5-10.
'Summer Love' hyssop
Agastache 'Summer Love' is a hybrid between A. cana and A. pallidiflora. Hardy in Zones 6-10, it's a good choice for hot, humid climates. Unlike many hyssops, the flowers and foliage have little fragrance. It grows to 3 feet tall.
'Tango' hyssop
Agastache barberi 'Tango' is an orange hybrid hummingbird mint that bears spikes of fragrant, soft orange blooms that attract hummingbirds, butterflies, and bees throughout the summer. At just 18-24 inches tall, it's a compact plant that performs well in beds and borders as well as in container gardens in zones 5-10.
Tutti Frutti hyssop
Agastache barberi 'Tutti Frutti' bears raspberry-red flowers on foot-long spikes. The gray-green foliage emits a lemony scent. It grows 3-6 feet tall in zones 6-10.
Companion Plants for Agastache
Bee Balm
Bee balm goes by many names but it's a sure bet for almost any garden in zones 3-9. Like agastache, bee balm prefers full sun and well-drained soil. It is drought-tolerant once established but prefers a little extra moisture during the hottest summer months.
Dianthus
Dianthus makes a great low-growing companion for agastache in zones 3-10. Look for creeping groundcover varieties that feature blue-green foliage and a blanket of starry blooms in shades of pink, purple, red, white, and yellow.
Milkweed
ROB CARDILLO
If planting agastache in a meadow-like setting look to another butterfly favorite, milkweed, as a companion plant. The low-maintenance perennials love full sun and, like agastache, can thrive in poor soil and low-water conditions. Milkweed is hardy in zones 3-9.
Garden Plans for Agastache
This colorful garden plan is filled with blooming perennials that bring color and interest to your garden from summer into fall. Everything here is designed to thrive in full sun and bloom through heat, humidity, and drought. In this pretty patch, you'll find flashes of orange from butterfly weed and pools of purple from aster and blazing star—all low-maintenance and sure to entice butterflies, bees, and other helpful pollinators
Frequently Asked Questions
- Is agastache an invasive plant?Agastache plants are not considered invasive and are, in fact, native in parts of North America—particularly the prairies, plains, and forested areas of the upper Midwest and Canada. That said, it will readily self-seed when left to grow in favorable conditions. To prevent agastache from spreading rampantly, deadhead the blooms before they wither and drop seeds.
Agastache plants are not considered invasive and are, in fact, native in parts of North America—particularly the prairies, plains, and forested areas of the upper Midwest and Canada. That said, it will readily self-seed when left to grow in favorable conditions. To prevent agastache from spreading rampantly, deadhead the blooms before they wither and drop seeds.
- How many years do agastache plants live?Agastache plants are short-lived perennials that will likely last only 2 to 4 years in most climates (zones 4-10). They will, however, self-seed new plants each season if allowed.
Agastache plants are short-lived perennials that will likely last only 2 to 4 years in most climates (zones 4-10). They will, however, self-seed new plants each season if allowed.
- Are anise hyssop and hyssop the same thing?It’s a little confusing given the common names, but no. Anise hyssop (Agastache Foeniculum) is a herbaceous perennial and member of the mint family (Lamiaceae) that is native to North America. Hyssop (Hyssopus officinalis) is a small herbaceous or woody shrub that is native to the Mediterranean and western Asia. While also a member of the mint family, hyssop is a part of the Hyssopus genus.
It’s a little confusing given the common names, but no. Anise hyssop (Agastache Foeniculum) is a herbaceous perennial and member of the mint family (Lamiaceae) that is native to North America. Hyssop (Hyssopus officinalis) is a small herbaceous or woody shrub that is native to the Mediterranean and western Asia. While also a member of the mint family, hyssop is a part of the Hyssopus genus.
- Why are my agastache leaves droopy?The most likely culprit of droopy leaves is underwatering. However, if your plant has weak stems and droopy leaves, it may be a sign of overly fertile soil. Alternatively, if the leaves of your agastache are droopy and yellow with mushy stems, you may be overwatering the plant. Scale back on supplemental watering and let at least the top inch of soil dry out completely before watering again.
The most likely culprit of droopy leaves is underwatering. However, if your plant has weak stems and droopy leaves, it may be a sign of overly fertile soil. Alternatively, if the leaves of your agastache are droopy and yellow with mushy stems, you may be overwatering the plant. Scale back on supplemental watering and let at least the top inch of soil dry out completely before watering again.