Threadleaf giant hyssop (Agastache rupestris)

Also known as: Threadleaf Giant Hyssop, Licorice Mint

Threadleaf giant hyssop (Agastache rupestris) is notable for its tall, slender appearance and fragrant, needle-like leaves. It produces striking tubular flowers in shades of orange to salmon, which attract pollinators like hummingbirds and bees. This plant excels in full sun and well-drained soil, showcasing excellent drought tolerance. Its natural habitat includes rocky, dry areas, making it well-suited for arid conditions.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting

Attributes of Threadleaf giant hyssop

Lifespan

Perennial

Plant Type

Herb, Shrub

Plant Height

46 cm to 61 cm

Spread

30 cm to 45 cm

Leaf Color

Green Gray Silver

Flower Size

2.5 cm

Flower Color

Orange Pink

Images of Threadleaf giant hyssop

Quickly Identify Threadleaf giant hyssop

Narrow gray-green leaves, 2 inches (5 cm) long, with a licorice scent.

Burnt orange tubular flowers with two lips clustered on 10-12 inch (25-30 cm) spikes.

Square-shaped green stem, 0.2-0.4 inches (5-10 mm) thick, with opposite branching.

Aromatic foliage forming a bushy clump 1-1.5 feet (30-45 cm) wide.

Small dry capsules with four brownish nutlets, around 1/8 inch (3 mm) in size.

Scientific Classification of Threadleaf giant hyssop

Phylum

Vascular plants

Class

Dicotyledons

Order

Lamiales

Family

Mint

Genus

Giant hyssops

Species

Threadleaf giant hyssop

Planting and Growing of Threadleaf giant hyssop

Care Difficulty

Moderate

Watering Schedule

Every 2 days

Sunlight Requirements

Full sun

Sunshine Duration

6-10 hours

Ideal Temperature

65-75℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6.5-7.5

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Plastic, Ceramic

How to Water Threadleaf giant hyssop?

When watering Agastache rupestris, ensure the soil is thoroughly moist but not waterlogged. It thrives when given about 250 ml each session, letting the water drain completely through to ensure water reaches the root zone without causing over-saturation.

What are the symptoms of an underwatered Threadleaf giant hyssop? ›

What should I do if my Threadleaf giant hyssop is not getting enough water? ›

What are the symptoms of an overwatered Threadleaf giant hyssop? ›

How to save an overwatered Threadleaf giant hyssop? ›

What Are the Sunlight Requirements for Threadleaf giant hyssop?

Sunlight Requirements: Full sun

Duration of light: 6-8 hours

Agastache rupestris flourishes under conditions of full sun exposure. Ensuring six to eight hours of direct sunlight daily results in vibrant blooms and healthy foliage, enhancing its ornamental value and ecological role in attracting pollinators.

Best Time for Sun Exposure ›

Natural Environment Simulation ›

Seasonal Sunlight Adjustments ›

What Is the Ideal Temperature Range for Threadleaf giant hyssop?

Ideal Temperature: 65 ~ 75℉

Agastache rupestris prefers a temperature range of 65-75°F for optimal growth. This range supports photosynthesis, respiration, and transpiration, all vital for its health. Proper climate control helps this plant to flourish indoors or outdoors.

What Soil is Best for Threadleaf giant hyssop?

Soil type: Sandy soil, Sandy loam, Loam

Soil PH: 6.5 ~ 7.5

Agastache rupestris thrives in well-draining soil that prevents water from pooling around its roots, thus avoiding root rot. This ensures the roots receive ample air circulation, contributing to healthy plant growth and vibrant foliage. This plant benefits from soil enriched with organic matter, providing the necessary nutrients for its development. Adding compost or well-rotted manure can enhance soil fertility, encouraging robust growth and prolific blooming. While Agastache rupestris tolerates a range of soil pH, it prefers slightly alkaline conditions. This alkalinity supports nutrient availability and overall plant health, ensuring vibrant blooms and resilience against pests.

How to Fertilize Threadleaf giant hyssop?

Fertilizer type: Balanced

For Agastache rupestris, it's essential to strike a balance in fertilization. Use a diluted liquid fertilizer at half the recommended strength, about 1 teaspoon per gallon of water. This ensures the plant receives nutrients without risking fertilizer burn.

How to Prune Threadleaf giant hyssop?

Pruning Time: Spring, Autumn

Begin your pruning by removing any dead, damaged, or diseased stems. Cutting these down to the base helps prevent any infections while removing unsightly parts. To maintain a pleasing shape, cut back leggy or overgrown stems. Trim these branches to just above a leaf node or a bud to encourage compact and full growth. Regularly deadhead spent flowers throughout blooming seasons, particularly in spring and autumn. This encourages continued blooming and prevents seed spread. More About Pruning Techniques→

How to Propagate Threadleaf giant hyssop plant?

Propagate Time: Spring, Late spring, Early spring

Sow seeds on the surface of a well-drained seed starting mix, lightly cover with soil, and maintain consistent moisture until germination occurs in 14-21 days.

Select 3-5 inch cuttings from healthy plants, remove lower leaves, dip in rooting hormone, and plant in a perlite and peat moss mix. Keep under indirect light.

Gently lift mature plants, separate root clumps ensuring each has shoots and roots, and transplant immediately into prepared soil for optimal re-establishment.

More About Propagating Techniques→

How to Repot Threadleaf giant hyssop plant?

Repotting frequency: Every 2-3 years

Agastache rupestris should be repotted when its roots begin to outgrow the current pot. Signs include roots growing through drainage holes, or if the plant appears stunted or water-logged. Early spring or early autumn are ideal times, allowing the plant to establish before summer heat or winter chill.

Select a pot that is 1-2 inches larger in diameter than the current one. It should have ample drainage holes to enable excess water to escape, preventing root rot. A terracotta pot can be beneficial, as it helps wick away moisture and mimics the natural dry environment this plant thrives in.

Use a well-draining cactus mix, ideally with added perlite or sand to ensure aeration. This soil choice aids in preventing water retention, mimicking the plant's natural arid environment, promoting healthier root growth and reducing the risk of fungal infections.