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How to Grow Agastache Plants: Expert Advice for Enthusiasts

Wondering how to grow the healthiest and most attractive Agastache plants? Read on, friends!

Agastache is a gorgeous perennial plant known for its striking flowers and fragrant foliage. Not only is it a stunning addition to any garden, but it also attracts bees, butterflies, and hummingbirds. If you want to add a burst of color to your landscape while supporting local pollinators, this guide to just about everything you need to know about growing and caring for Agastache plants will point you in the right direction.

 

 

First Things First: How to Identify Your Agastache

Agastache comes in several varieties, each with unique characteristics. Common types include:

  • Agastache foeniculum (Anise Hyssop)
  • Agastache mexicana (Mexican Hyssop)
  • Agastache rugosa (Giant Hyssop or Korean Mint)
  • Agastache cana (Texas Hummingbird Mint)

These perennial flowering plants typically have tall spikes of flowers in varying hues of purple, pink, orange, and blue, further enhanced with aromatic foliage. What does it smell like? Agastache’s foliage has a minty, herb-ish fragrance, though some gardeners have said it smells like a mug of warm root beer! Identifying your Agastache type (cultivar) will help you tailor your care routine more effectively.

Anise Hyssop (Agastache foeniculum):

  • Flowers: Lavender-blue spikes, typically 3-4 inches long
  • Habit: Upright, bushy growth, reaching 2-4 feet tall and 1-2 feet wide
  • Foliage: Green leaves with a strong anise scent
  • Blooming period: Mid-summer to early fall

Mexican Hyssop (Agastache mexicana):

  • Flowers: Tubular flowers in shades of red, pink, or lilac, in dense spikes
  • Habit: Upright, somewhat spreading, typically 2-3 feet tall and wide
  • Foliage: Dark green leaves with a minty-licorice scent
  • Blooming period: Summer to fall

Giant Hyssop/Korean Mint (Agastache rugosa):

  • Flowers: Lavender to purple-blue spikes, often larger than A. foeniculum
  • Habit: Tall and upright, can reach 4-6 feet in height and 2-3 feet wide
  • Foliage: Aromatic green leaves with a minty-anise scent
  • Blooming period: Mid-summer to fall

Texas Hummingbird Mint (Agastache cana):

  • Flowers: Rose-pink to magenta tubular flowers in loose spikes
  • Habit: Compact and bushy, typically 1-3 feet tall and 1-2 feet wide
  • Foliage: Gray-green leaves with a minty fragrance
  • Blooming period: Summer to fall

These varied characteristics in blossom color, plant size, and growth habit make each type of Agastache uniquely suited for diverse garden designs and purposes. For example:

  • Anise Hyssop is great for mid-border plantings and herb gardens.
  • Mexican Hyssop works well in containers or as a colorful accent plant.
  • Giant Hyssop is ideal for back-of-border plantings or naturalized areas.
  • Texas Hummingbird Mint is perfect for rock gardens or small spaces.

When choosing an Agastache cultivar for your garden, consider not only the growing conditions but also how its specific characteristics will fit into your overall garden and landscape design.

Choosing the Right Location

All Agastache plants thrive in full sun, requiring at least six hours of direct sunlight daily. Most varieties are heat and drought-tolerant, once established, making them perfect for sun-soaked garden spots. When selecting a location, consider the following:

  • Sunlight: Full sun is ideal.
  • Soil: Well-draining soil is crucial to healthy Agastache plants.
  • pH: Slightly acidic to neutral (6.0-7.5pH) soil is preferred.
  • Hardiness: Varies by species but is generally planted as a perennial in USDA zones 4-10.

Soil Preparation and Planting

Before planting, amend your soil with organic matter like compost or well-aged manure to improve fertility and drainage. Clay soil may need to be amended with sand or very small gravel or pebbles.

  1. Dig a hole deeper and wider than the root ball. Leave enough room to line the bottom of the hole with loose soil to enable the roots to more easily take hold in their new home.
  2. Place the plant in the hole; the top of the soil around your plant should be even, or just below the level of the soil you are planting in.
  3. Backfill with soil, gently pressing the soil around the base to eliminate air pockets and to make good contact with the roots.
  4. Water thoroughly after planting, using a mist or light spray so that the soil is not displaced and the plant is not stressed.

Watering and Mulching

Agastache plants are drought-tolerant, once established, but require moderate watering until then. The emergence of new growth is a good indicator that your Agastache has taken a good hold in its new environment.

Follow these watering guidelines:

  • Water deeply once a week or when the top inch of soil feels dry.
  • Avoid overwatering to prevent root rot.
  • Apply a 2-inch layer of organic mulch around the base, keeping it away from the stem. Organic mulch will gradually decompose, providing natural nutrients to your plants, and will also help to retain water and inhibit weed growth.

Fertilizing and Maintenance for Optimal Health

Just as we humans and our pets require sustenance and grooming, plants do too. To keep your Agastache healthy and blooming, follow these care tips:

  1. Fertilize with a balanced, slow-release fertilizer in spring and mid-summer during the height of bloom production.
  2. Pinch back tips when plants are about 6 inches tall to encourage bushier, fuller growth.
  3. Deadhead spent flowers to promote continuous blooming. Removing the spent blooms in a timely manner will guarantee continuous flowering, as well as preventing disease by keeping fallen blossoms off the soil around your plants. Oh…it also makes your garden more aesthetically pleasing.
  4. Cut back stems to about 4 inches above the ground in late fall or early winter.

Overwintering Tips

In colder climates, follow these steps to help your Agastache survive winter:

  1. Apply a thick layer of mulch (4-6 inches) around the base of the plant in late fall to protect the roots from freezing temperatures. In the spring, remove the old mulch and replace it with a lighter layer, keeping it away from the stems.
  2. If your Agastache is in a container, move it to a sheltered location, such as a garage or unheated greenhouse, to protect it from extreme wind and cold.
  3. In areas with severe winters, consider covering your plants with a breathable frost cloth or burlap for additional protection.

Pest and Disease Control

Agastache is relatively resistant to pests and diseases. However, watch out for:

Root Rot: This can be a problem if your Agastache plants are being overwatered. If you ever notice standing water around or near your plants, they may be getting too much water. Stop watering until the top inch of soil is dry to the touch. Root rot may be the culprit if your plants are experiencing stunted or slowed growth, yellowing of its leaves, especially the lower leaves, plant wilting, and flowers drooping or dropping.

Aphids or Whiteflies:

Aphids have tiny bodies, kind-of pear-shaped and are usually green, though they can also be white, brown, gray, black, pink or yellow in color. The quicker you identify them, the better. Aphids will hide on the undersides of leaves, so if you notice misshapen, yellowing, curled or stunted leaves, go down under! It is actually a good practice to check every few days for aphids. Several generations can breed in one season and they can quickly become a real nuisance.

Whiteflies may look like moving grains of rice, though they most typically look kind of triangular, due to the position of their wings. Whiteflies will usually be found on the undersides of your plants’ leaves but will fly up when disturbed.  

Both of these pests damage your plants by sucking the juice out, leaving a sticky residue, known as honeydew. Ants are attracted to honeydew, so that may be an indicator of a pest problem.  Treatment with insecticidal soap is recommended.

Propagate and Multiply!

Expand your Agastache collection through:

  • Seeds: Sow indoors 6-8 weeks before last frost or directly in the garden after frost.
  • Cuttings: Take softwood cuttings in late spring or early summer.
  • Division: Divide mature plants in early spring or fall.

What Looks Good Planted Alongside Agastache?

Agastache pairs well with other drought-tolerant and pollinator-friendly plants such as:

  • Echinacea (Coneflowers), a perennial available in different heights and numerous colors.
  • Lavandula (Lavender), a fragrant herb plant.
  • Salvia (Sage), an herb that’s also suited to container gardening.
  • Rudbeckia (Black-eyed Susan), a perennial with large, brown to black eyes surrounded by daisy-like petals.
  • Gaillardia (Blanket Flower), a native perennial that still blankets the uninhabited plains of the U.S.

We hope that this guide will have you well on your way to growing beautiful, thriving Agastache plants that will add vibrant color to your garden and attract beneficial pollinators. 

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