Anise Hyssop: How To Develop and Care For Agastache Foeniculum

Agastache hyssop, 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 plant sends up narrow flower spikes that can create lovely perennial 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 plants 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 native plants to most of the US! 

Quick Care Guide

About Anise Hyssop

Anise hyssop has similar growth habits and scents to other plants in the mint family.

Agastache foeniculum, or Anise hyssop, shares a common name with many other plants 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. 

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 plant 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. 

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 4 inches long with toothed margins. Although they are perennial, they are short-lived, and most plants last about 2-3 years.

Anise Hyssop Care

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! 

Sun and Temperature

Anise hyssop thrives in full sun but can tolerate partial shade.

Anise hyssop prefers full sun. It can also survive in part shade, though it may grow tall and lanky when it receives less than 6 hours of sunlight per day.

For the bushiest and fullest plants possible, it’s best to choose a planting site that receives 6-8 hours of sunlight per day – unless you live in an area that regularly receives temperatures above 80 degrees Fahrenheit during the summer. 

In this case, partial shade may benefit them by providing a break from extreme heat. 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 degrees Fahrenheit at night and 65-75 degrees during the day.

These perennial plants can tolerate temperatures down to 10 degrees Fahrenheit in the winter.  During the winter, they will die back to the ground, but lighter green foliage will return in the spring. 

Water and Humidity

Anise hyssop is drought-tolerant once established but requires consistent moisture during establishment.

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 of the plant 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

Anise hyssop requires well-draining soil, with sandy soil being preferable.

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 your plants with well-drained soil. 

Fertilization

Anise hyssop generally requires compost at the time of planting and does not need additional fertilizer.

Amending the planting site with compost once at the planting time is generally all the fertilizing your Anise hyssop will need. Additional fertilizer is not necessary. Fertilizer 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 this plant, 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 plant. 

Pruning & Deadheading

Pinch back foliage in spring and deadhead spent flowers for additional bloom.

In early spring, the tips of lime-green foliage can be pinched back 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 6 inches of the stalks standing to provide protection over the winter. They can be cut back the following spring, just before new growth emerges.

Additionally, when these stalks are left standing, the plants 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

Collecting or letting seeds fall on the soil’s surface in late fall or winter yields the best results.

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 parent plants only last for 2-3 years. As it drops seeds, new plants 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 & Transplanting

Anise hyssops can be grown in containers, and repotting may be necessary if growth has slowed.

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

If plant 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. 

Troubleshooting

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

Delay pruning Anise hyssop until early spring and offer winter protection in areas with extreme cold.

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

It can be 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 plants. As mentioned above, choosing a location with well-drained soil is imperative for this reason.

Pests

Agastache foeniculum has no known major pest issues.

Diseases

Prevent fungal issues by providing good air circulation and avoiding overwatering.

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

Most of the fungal issues can be treated with a copper fungicide. Success varies, and it’s best to remove infected plant material before it can spread. 

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

Q: Does anise hyssop like sun or shade?

A: 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. 

Q: Is anise hyssop invasive?

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

Q: Is anise hyssop the same as lavender?

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

Q: Can you eat anise hyssop?

A: Yes, both the flowers and the foliage are edible. 

Q: Does anise hyssop repel bugs?

A: 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! 

Q: Is anise hyssop toxic to pets?

A: It is not considered to be toxic to pets. 

Q: Do you cut back anise hyssop in the fall?

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