How to Grow and Care for Agastache

Varieties of Agastache

• Agastache cana, commonly referred to as hummingbird mint, is the most popular type of agastache. It produces an abundance of soft rose pink flowers and thrives in containers. The blooming period extends from early summer to late autumn. This plant is native to the southwestern United States and Mexico and is well-suited for xeriscape gardens due to its ability to withstand the heat and drought of arid climates. (USDA zones 5-10) 
• Agastache foeniculum is known as anise hyssop. This perennial plant forms clumps and is indigenous to parts of the Midwest and the Great Plains. It comes in various colors, with blue to lavender purple being the most common. (USDA zones 6-9) 
• Agastache scrophulariifolia, commonly known as purple giant hyssop, can reach a height of six feet. It blooms late with pale purple or pink flowers. (USDA zones 4-8) 
• Agastache rupestris, also called licorice mint hyssop or threadleaf giant hyssop, features soft orange flowers set against dusty purple calyxes. The fragrance is a delightful combination of licorice and mint. (USDA zones 5-8) 
• Agastache ‘Blue Fortune’ is a European hybrid known for its delicate periwinkle blue flowers. (USDA zones 5-9)
• Agastache ‘Firebird’, a hybrid variety, is notable for its grey-green foliage and coppery orange blossoms that attract hummingbirds. (USDA zones 6-9) 
• Agastache rugosa ‘Honey Bee Blue’ is a cultivated type of purple giant hyssop characterized by bushy flower spikes in pale lavender blue and slightly larger bluish green leaves. (USDA zones 5-
  

  Trimming

  

  During the spring season, it is advisable to trim the new growth of the plant to promote a bushier appearance. While removing spent flowers is not mandatory, it helps maintain the plant’s neatness and prevents agastache from producing seeds and spreading on its own, a behavior it tends to do abundantly.

  The extent of additional trimming required depends on whether agastache is being cultivated as a perennial or an annual plant. For perennial growth, trim the plant by approximately one-third in the spring to stimulate fresh growth. Continuously trim and remove spent flowers, but cease this practice in midsummer as the new growth becomes susceptible to cold conditions, posing a risk to the plant’s survival during winter. If grown as an annual, it is permissible to trim and remove spent flowers throughout the entire season.

  How to Propagate Agastache

  

  Agastache can be propagated by division or from cuttings. Here are the steps to grow agastache from cuttings:
• Use pruning shears to cut 6- to 8-inch pieces of green stem in late summer or fall.
• Remove the lower leaves and gently scrape the exposed stem with a sharp knife.
• Dip the scraped part in rooting hormone and plant the stems in a small pot with a sterile mix of perlite and sand.
• Water lightly and cover with a large plastic bag or humidity dome.
• After 2 to 3 weeks, check for root development by gently pulling on the stem.
• Keep the soil slightly damp and uncover when new leaves start to grow.

Steps for Growing Agastache From Seed

Once agastache is well-established, it will spread quite vigorously from seed. To harvest the seeds, allow them to fully mature on the plant until they are completely dry, but gather them before they open and scatter. Turn the seed heads upside down into a bowl or paper bag to collect the seeds.

Agastache seeds require cold stratification to sprout, so the most effective way is to sow them directly in the garden in the autumn, allowing them to be exposed to the cold winter temperatures:

• Gently press the seeds into the loosened soil surface, no more than ¼ inch deep.
• Keep the seeds moist every few days during the autumn.
• If your area receives winter snow, this will provide enough moisture for them to sprout in the spring. If your winters are dry, occasional light watering of the seeds will aid in their germination when the spring temperatures rise.

Planting and Replanting Agastache

Agastache can be cultivated in pots as long as adequate space is provided for its extensive root system. Opt for a pot with sizable drainage holes that is at least two to three inches larger in diameter than the original pot. Since Giant hyssop grows quite tall and is prone to toppling, consider selecting a dwarf variety instead. Utilize well-draining potting soil and bear in mind that potted plants require more frequent watering and fertilizing compared to those in the ground.

When the plant’s roots have outgrown its current container, transplant it into a larger pot with fresh potting soil.

Surviving the Winter

If you have a type of agastache plant that is a perennial and can withstand the winter conditions in your area, you do not have to provide any protection for it during the winter season. The plant naturally becomes dormant in the autumn, so it is advisable not to trim the dry brown stems immediately. It is better to leave them on the plant and wait to trim them back to ground level in the spring to allow space for fresh growth.

Pests and Plant Diseases Frequently Found

Agastache is resistant to major pest infestations and diseases. However, in soil with inadequate drainage, the plant may develop root rot. Common fungal diseases that may affect Agastache include powdery mildew and leaf spot.

Tips for Inducing Agastache to Flower

Agastache is highly appreciated for its long-lasting flowering period. Unlike many other perennial plants, it often blooms within the first year. If it fails to bloom, it is usually due to over-fertilized soil.

Blooming Season

The blooming period of agastache slightly varies depending on the species and climate, but typically falls in the summer, from midsummer to late summer, and sometimes extending into early fall.

Duration of Agastache Blooms

Under optimal conditions, agastache can flower for several months, throughout the summer.

Appearance and Fragrance of Agastache Flowers

Agastache displays tall flower spikes with a strong, spicy aroma. The scent varies based on the specific species. For instance, anise hyssop emits a fragrance reminiscent of licorice, while other types may smell like pink bubble gum, root beer, lavender, or mint.

Promoting More Flowering

To encourage branching, trim the growth tips in spring when the plants reach around 6 inches in height. Consistent deadheading throughout the growing season promotes continuous blooming. Refer also to the Pruning section for more details.

Post-Blooming Care for Agastache

If you prefer to prevent self-seeding, remove the seed heads before they release the seeds.

Removing Spent Agastache Flowers

Eliminating spent flowers from agastache encourages further blooming and helps manage the plant’s tendency to self-seed.