How to Grow and Care for Agastache

While tricky to pronounce ("ah-GAH-stuh-kee"), this prolific herbaceous perennial with over 22 different species (many of them native to North America) is well-loved for its ability to lure pollinators. The name "agastache" is derived from the Greek and essentially means a very large ear of grain, referring to the abundant flower spikes. In addition to being a beneficial garden plant, agastache is also beautiful, available in a wide range of vivid colors from light pink to deep purple, blue, red, orange, and white. It has a minty, herby fragrance. The leaves and flowers are edible and they can be dried to make a delicious herbal tea.

Agastache is deer-resistant and rabbit-resistant, and a veritable magnet for bees, butterflies and hummingbirds. It's also a fairly long-blooming perennial, flowering all summer and offering vivid color for weeks on end. It is a close relative of catmint, another pollinator-friendly flowering perennial.

Agastache Care

Once established, agastache does not need much care and it will reliably come back every year. If grown in suitable conditions, hummingbird mint and other agastache varieties can live for many years. Here are the main care requirements for growing agastache:

• Plant it in a location where it gets full sun and the soil is well-drained.
• Water it only occasionally but deeply.
• Make sure not to overfertilize it. It does best in lean soil alongside other similar plants that like similar growing conditions.
• Cut back spent flower spikes to encourage reblooming and more growth during the bloom season. This also prevents it from self-seeding.

Light

Agastache likes full sun and can easily tolerate the hottest sun of the day, so keep this in mind when deciding where to plant it.

Soil

This desert plant grows best in lean soils with low levels of nutrients. Adding a bit of sand to loamy soils can improve their suitability for growing agastache.

Water

Though it enjoys a deep watering, consistently moist conditions are not suitable for agastache. Watering routines should ideally follow desert conditions: occasional blasts of heavy rain followed by days of hot sun.

Temperature and Humidity

Agastache can handle high temperatures better than many garden plants, so it's perfect for that spot that gets strong afternoon sun. Humidity isn't suitable for agastache and growing it in a persistently moist spot will probably cause its roots to rot and its leaves to yellow. It's also important to make sure the roots of the plant stay dry in winter, especially if growing in USDA zones 5 or 6. Placing some gravel around the base of the plant as a sort of mulch barrier can help prevent root rot from frozen soil that defrosts slowly in spring.

Fertilizer

Agastache has no need of extra fertilizer but a top dressing of compost in autumn will keep it healthy.

Types of Agastache

• Agastache cana, commonly known as hummingbird mint, is the most widely grown type of agastache. It blooms abundantly with soft rose pink flowers. It does well in containers and has a long blooming period from early summer to late autumn. It is indigenous to the southwestern United States and Mexico and is suitable for xeriscape gardens, with its tolerance for the heat and drought of arid climates. (USDA zones 5-10) 
• Agastache foeniculum is known under the common name of anise hyssop. This clump-forming perennial is native to parts of the Midwest and the Great Plains. It comes in different colors; blue to lavender purple is the most common. (USDA zones 6-9) 
• Agastache scrophulariifolia, commonly known as purple giant hyssop, grows six feet tall. It is late-flowering type with pale purple or pink blooms. (USDA zones 4-8) 
• Agastache rupestris, which is commonly known as licorice mint hyssop or threadleaf giant hyssop, is a variety that has soft, orange-colored flowers contrasted with dusty purple calyxes. The fragrance combines licorice and mint, a real feast for the senses. (USDA zones 5-8) 
• Agastache 'Blue Fortune' is a European hybrid with soft periwinkle blue flowers. (USDA zones 5-9)
• Agastache ‘Firebird', a hybrid, is a powerhouse of color with its grey-green leaves and coppery orange flowers that attract hummingbirds. (USDA zones 6-9) 
• Agastache rugosa ‘Honey Bee Blue' is a cultivar of purple giant hyssop with soft bushy flower spikes of pale lavender blue and slightly larger leaves of bluish green. (USDA zones 5-8)
• Agastache barberi ‘Tutti Frutti’, also known as agastache Tutti Frutti, has raspberry-red flowers and scented gray-green leaves. It is mostly grown as an annual. (USDA zones 6-10)
• Agastache aurantiaca ‘Tango’, also known as Tango hummingbird mint, is a dwarf hummingbird mint. This hybrid variety has bright orange flowers all season long. (USDA zones 5-9)
• Agastache ‘Morello’, also known as Morello hummingbird mint, is a hybrid with bright, burgundy-rose flower clusters. The plant has an exceptional upright growth habit. (USDA zones 5-10)

Pruning

In the spring, pinch new growth so the plant gets bushier. Deadheading spent flowers is not necessary but it keeps the plant tidier and it also prevents agastache from setting seed and self-seeding, which it does prolifically.

Additional pruning depends on whether you are growing agastache as a perennial or annual. If you grow it as a perennial, cut the plant back by about one-third in the spring to encourage new growth. Keep pinching and deadheading but stop in midsummer because the new growth is vulnerable to cold and it might endanger the plant’s survival in the winter. If you grow is as an annual, you can pinch and deadhead the plant all season long.

Propagating Agastache

Agastache can be divided or propagated from cuttings. Here is to grow agastache from cuttings:

1. Use pruning shears to remove 6- to 8-inch pieces of green stem in late summer or fall.
2. Strip off the lower leaves and lightly scrape the exposed stem with a sharp knife.
3. Dip the scraped portion in rooting hormone and place the stems in a small pot containing a sterile mix of perlite and sand.
4. Water gently and cover with a large plastic bag or humidity dome.
5. Check for root growth in 2 to 3 weeks by gently tugging on the stem.
6. Keep the soil slightly moist and remove the cover when new leaves begin to sprout.

How to Grow Agastache From Seed

Once established, agastache will spread fairly vigorously from seed. To collect the seeds, let them mature on the plant until they are fully dry but get them before the open and disperse. Tip the seed heads upside down into a bowl or paper bag to collect the seeds. 

Agastache seeds need cold stratification to grow, so the best method is to direct sow them in the garden in the fall, so they are exposed to the winter cold temperatures: 

1. Press seeds gently into the loosened soil surface, no deeper than ¼ inch deep. 
2. Moisten the seeds every few days in the fall. 
3. If your region gets winter snow this will give them enough moisture to germinate in spring. If your winters are dry, occasional light watering of the seeds will help them to germinate when the spring temperatures warm up.

Potting and Repotting Agastache

Agastache can be grown in containers as long as you give the plant enough room for its large root system. Choose a container with large drainage holes and a size that is at least two to three inches larger in diameter then the nursery pot. Giant hyssop grows very tall and it is more prone to topple over so you might be better off with a dwarf variety. Use well-draining potting soil and keep in mind that container-grown plants need more frequent watering and fertilizer than plants in the landscape.

Repot the plant to a larger container with fresh potting soil when its root system has filled the pot.

Overwintering

A perennial agastache variety that is winter-hardy in your climate does not need protection during the winter. The plant goes into dormancy in the fall but don’t cut the dead brown stems back just yet. Leave them on the plant and only cut them back to the ground in the spring to make room for new growth.

Common Pests & Plant Diseases 

Agastache is not susceptible to serious pest or disease problems. In poorly drained soil, the plant may get root rot. Possible fungal diseases include powdery mildew and leaf spot.

How to Get Agastache to Bloom

The plant is valued as a long-lasting bloomer. Unlike other perennial flowers, it often blooms the first year. If it does not bloom, the cause if often that the soil has been over-fertilized.

Bloom Months

The bloom time of agastache varies slightly depending on the type and climate but generally, it blooms in the summer, from midsummer to late summer, even into the early fall.

How Long Does Agastache Bloom

When grown in ideal conditions, it can bloom for months and all summer long.

What Do Agastache Flowers Look and Smell Like?

Agastache has tall flower spikes with a pungent, spicy fragrance. The scent varies depending on the species. Anise hyssop has a licorice-like scent whereas the smell of others is likened to pink bubble gum, root beer, lavender, or mint.

How to Encourage More Blooms

Pinch back the growth tips in the spring when the plants are about 6 inches tall to encourage branching. Removing the spent flowers throughout the growing season encourages continuous blooming. See also under Pruning.

Caring for Agastache After It Blooms

If you do not want the plant to self-seed, remove the seed heads before they can disperse the seeds.

Deadheading Agastache Flowers

Deadheading the flowers of agastache encourages more blooms and it’s a way to control the plant's self-seeding habit.