How to Plant, Grow, and Care for Anise Hyssop

Anise hyssop, sometimes called lavender giant hyssop, is a prairie perennial that pulls in pollinators. Kelli Klein has all the information to grow and care for these colorful perennials.

A shot of a composition of purple flowers called anise hyssop

Contents

Agastache foeniculum, also known as anise hyssop, is a powerhouse when it comes to attracting hummingbirds, butterflies, and large native bees to your wildflower gardens. As a member of the mint family, it is also sometimes referred to as hummingbird mint. 

The tubular flower shape and abundance of nectar are what attract hummingbirds and also provide bee forage. During peak bloom, summer to early fall, this wonderful perennial sends up narrow flower spikes that can create lovely borders along butterfly gardens. 

Not only are they a beneficial pollinator attractant, but the purple flowers and foliage are also edible. The anise hyssop plant is sometimes grown in herb gardens and used as a healing herb.

The edible flowers are said to have a licorice scent with a similar taste, thus the nickname anise hyssop. It combines well with other edible native perennials, such as bee balm

Growing anise hyssop is a breeze! They are drought-tolerant once established and not picky about soil types. Their ease of growth, lack of pests, and no need for fertilizer make them an attractive choice for those interested in organic gardening as well. 

They readily self-seed, which means you can collect anise hyssop seed and have a never-ending supply of these natives to most of the US! 

Plant Overview

A cluster of purple flowers gracefully tower on delicate stems. Their rich hue contrasts beautifully against the backdrop of verdant foliage below, creating a harmonious botanical tableau in full bloom.
Plant Type Flowering perennial herb
Family Lamiaceae
Genus Agastache
Species Agastache foeniculum
Native Area North America
Exposure Full Sun to partial shade
Height 2-4’
Watering Requirements Low
Pests & Diseases Deer-resistant, root rot, leaf spots, powdery mildew
Maintenance Low
Soil Type Well-draining, rich to sandy
Hardiness Zone 4-9

What is Anise Hyssop?

Agastache foeniculum, or anise hyssop, shares a common name with many others in the mint family that have similar growth habits, scents, and appearance. Other common names include blue giant hyssop, fragrant giant hyssop, and lavender hyssop. 

Native Area

Tall, purple flowers in full bloom, emitting a subtle, sweet fragrance into the surrounding garden.
The flowers are native to North America.

Despite the common name, it is not closely related to true hyssop (Hyssopus spp.), a European plant traditionally used as a healing herb. Despite the common name, anise, and its licorice scent, it is not related to Pimpinella anisum, a completely different plant in the carrot family. 

This variety is native to north-central and northern parts of North America, most notably the Great Plains and other prairies. This clump-forming perennial is especially well suited to dry upland forested areas. 

Characteristics

A close-up shot of several developing purple flowers alongside its leaves in a well lit area
The plants feature upright stalks of flowers with varying colors and leaves with toothed margins.

The most common flower color of this native perennial is purple. However, there are many other varieties and colors, such as powder blue flowers, clear blue flowers, red-violet flowers, creamy white flowers, and pink flowers. A few of these varieties are ‘Blue Blazes’, ‘Blue Fortune’, ‘Purple Haze’, and ‘Desert Sunrise’. 

The flower spikes bloom along tall upright stalks that attract bees. These flower spikes are attached to square stems decorated with medium green anise hyssop leaves up to four inches long with toothed margins. Although they are perennial, they are short-lived, and most last about two to three years.

Planting

An overhead shot of purple flower stalks in a bright sunny area outdoors
Place the flowers in an area with loosened soil amended with compost.

Start the process by preparing the area by loosening the soil and mixing in compost to enhance drainage and fertility. Sow seeds directly into the garden in early spring after the last frost or start them indoors six to eight weeks earlier. Lightly press the seeds into the soil surface without covering them, as they need light to germinate. Water gently to keep the soil consistently moist until germination occurs, usually within 10-14 days.

Once seedlings are a few inches tall, thin them out to 12-18 inches apart to allow for airflow and growth. Water regularly during dry spells.

How to Grow

Regardless of what color of Agastache foeniculum you choose, it is easy enough to grow anise hyssop with its low maintenance care requirements. Providing them with their ideal growing conditions will ensure they readily self-seed and produce flowers in your butterfly garden for years to come! 

Light

A shot of a small composition of developing flowers basking in bright sunlight outdoors
The plants prefers full sun to partial shades.

Anise hyssop prefers full sun. It can also survive in part shade, though it may grow tall and lanky when it receives less than six hours of sunlight per day.

For the bushiest and fullest perennials possible, it’s best to choose a planting site that receives six to eight hours of sunlight per day – unless you live in an area that regularly receives temperatures above 80°F during the summer. In this case, partial shade may benefit them by providing a break from extreme heat.

Water

An overhead shot of a black soaker hose on soil covered in mulch
Water at the base of the flowers with a soaker drip irrigation.

Anise hyssop is quite a drought-tolerant plant once established, which makes it the perfect choice for low-water use or xeriscape gardens. They will need consistent moisture in order to become established, however. During this time, it is best to water early in the day and avoid wetting the foliage. 

Water at the base with a soaker hose or drip irrigation. Since Anise hyssop is native to hot and dry areas, it does not do well with excessive moisture and humidity. Allow the area to dry out between waterings. 

Soil

A focused image of light brown sandy soil in big and small clumps.
Use a well-draining soil, preferably sandy soils.

The one thing that anise hyssop will not tolerate is poorly drained soils. The type of soil can vary widely as long as it is well-draining. Sandy soils are the preference because of their ability to drain away moisture and avoid standing water.

For this reason, you should also avoid planting your anise hyssop in a low-lying area or near a downspout. 

Avoid adding too much organic matter or compost to your soils, as these can retain too much moisture. If growing your anise hyssop in containers, you may want to add perlite to your potting mix to ensure you provide well-drained soil. 

Temperature

A close-up of purple flowers blooming gracefully contrasting with lush green leaves underneath, capturing the delicate beauty of nature in exquisite detail.
Ideal temperatures ranges between 55-60°F at night and 65-75°F during the day.

Anise hyssop does well in its native range, which includes areas throughout USDA growing zones 4-9. The ideal temperature range during the growing season is about 55-60°F (13-16°C) at night and 65-75°F (18-24°C) during the day.

These perennials can tolerate temperatures down to 10°F (-12°C) in the winter. At this time, they will die back to the ground, but lighter green foliage will return in the spring. 

Fertilizing

A hand holds a handful of dark, crumbly leaf mold compost, showing its rich texture and organic matter.
The plants does not need additional fertilizers and a site with compost is best.

Amending the planting site with compost once at planting time is generally all your anise hyssop will need. Additional fertilizer is not necessary. Fertilizers can cause anise hyssop to focus on foliage production rather than flowers and can also cause it to begin producing blue flowers later in the season. 

Too much fertility can cause a reduction in the essential oils found in the foliage and flowers, which can negate the purpose of cultivating, especially if you’re growing it as an herb for its fragrant foliage. Fertilizers can also cause it to grow too tall too quickly, resulting in a tall, leggy, floppy perennial. 

Maintenance

Close-up of a man's hand pinching off the flowering plants
Pinching and pruning can promote bushier and healthier growths.

In early spring, pinched back the tips of lime-green foliage to prompt bushier growth. Once they begin blooming, you may deadhead spent flowers to promote additional bloom. When grown as a perennial, it is not advisable to prune the stalks completely back at the end of the season. 

While pruning anise hyssop at most stages of growth can be beneficial, you’ll want to leave about six inches of the stalks standing to provide protection over the winter. Cut back the following spring, just before new growth emerges.

Additionally, when these stalks are left standing, they will go to seed and can self-sow and spread if you want even more violet-blue flowers of anise hyssop in your garden. 

Propagation

An overhead shot of a pile of flower seeds in a well lit area
Propagation can be done by seeds.

As mentioned above, anise hyssop can self-seed and spread year after year. It does not, however, have the potential to become invasive. Although it is a perennial, it is short-lived, and parents only last for two to three years. As it drops seeds, new ones will be ready to take their place. 

You can let seeds fall where they may in your perennial borders at the end of the season or collect seeds to sow them more intentionally throughout the landscape. Sowing seeds on the surface of the soil in late fall or winter yields the best results.

Most species require a period of cold stratification in order to germinate properly, but always check the seed packet for specific instructions. 

Repotting

A shot of several potted dwarf variety of flowers in a well lit area
Repotting is done with dwarf varieties once its roots poke out of drainage holes.

Most anise hyssops are grown directly in the ground. However, some dwarf varieties can be grown in containers. If you’ve chosen to grow in containers, you may come to a time when you must repot.

If growth has slowed significantly or you’ve noticed roots poking out of the drainage holes, then it’s time to consider repotting. 

Since anise hyssops are such short-lived perennials, you will likely get away with not needing to re-pot. This is provided that it is planted in an adequate-sized container to begin with.

Consult the planting tag that comes along with the variety that you’ve chosen or the seed packets for specific container recommendations. 

Common Problems

Anise hyssop is relatively trouble-free, especially when grown in its native habitat. That being said, there are a few things to keep in mind when choosing a planting site.

Growing Problems

A shot of developing plants showcasing its purple flowers in a well lit area
Growth problems occur during the plant’s dormancy.

Most growing problems occur in the winter when its dormant and most susceptible to damage. For this reason, it is recommended to delay pruning until early spring, just before new growth appears.

It is beneficial to offer winter protection in areas with extreme cold like coverage with burlap. Planting your hyssop in an area that isn’t well-drained can also put them at risk for diseases. It may grow more slowly, struggle to flower, and not self-seed as readily as healthier specimens. As mentioned above, choosing a location with well-drained soil is imperative for this reason.

Agastache foeniculum has no known major pest issues.

Diseases

A close-up of tangled roots with signs of rot and decay, as a hand gently holds a damaged section showing soft, discolored tissue.
Root rot and powdery mildew are common diseases caused by excess humidity and moisture.

Powdery mildew and root rot are fungal issues that are caused by or exacerbated by excess moisture and humidity. Provide your perennials with good air circulation. Keep the area around your flowers free of debris to help prevent these issues. 

Root rot, in particular, can be exacerbated by overwatering. Since anise hyssop can be quite drought-tolerant, it’s best to underwater it rather than risk overwatering it. The symptoms of rot will appear as a soft mushy stem, wilting, and of course, rotten roots. 

This type of rot is harder to recover from but can be remedied if there are still fresh, white roots that have not yet turned to mush.

Cut back the rotted roots and replant the pot into dry soil. If your anise hyssop is directly in the ground rather than in containers, cut back on watering and allow the area to dry out completely before watering again.

Frequently Asked Questions

Does anise hyssop like sun or shade?

Anise hyssop prefers full sunlight but will tolerate part shade. Part shade can be beneficial in places with extreme heat in the summer. Otherwise, opt for full sun.

Is anise hyssop invasive?

It is not considered to be invasive, though it will spread locally by self-seeding.

Is anise hyssop the same as lavender?

No, it’s not. It may have a similar appearance with lavender purple blooms. It’s also in the same family and is sometimes referred to as lavender hyssop, it is not the same as an actual lavender plant.

Can you eat anise hyssop?

Yes, both the flowers and the foliage are edible.

Does anise hyssop repel bugs?

Yes, its strong scent is said to simultaneously repel pests and attract beneficial insects and pollinators like bees and butterflies. Similar to hummingbird mint, it will also serve as a hummingbird magnet!

Is anise hyssop toxic to pets?

It is not considered to be toxic to pets.

Do you cut back anise hyssop in the fall?

Delay pruning your hyssop until early spring, just before new growth emerges.

 

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