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Giant Hyssop (Blue Giant Hyssop)

Agastache foeniculum

Family:

Mint family - Lamiaceae

The aromatic giant hyssop, with its mint and licorice-scented leaves and bountiful clusters of purple flowers, is a magnet for a wide range of pollinators.

Woodland garden

Woodland garden

Meadow or Grassland garden

Meadow / Grassland garden

Pollinator garden

Pollinator garden

Cutting garden

Cutting garden

Adaptable

Adaptable

Supports wide variety of wildlife

Supports wide variety of wildlife

High-value

High-value

Details

Emerges 

April, May

Seed collection

Flowers

July, August

blue flowers

Blue

purple flowers

Purple

September

Lifecycle

Perennial

Lifespan

Height

60

-

90

cm

Width

30

-

50

cm

Habit

Forbs

Upright

Upright

Spreading

Spreading

Clumping

Clumping

Herbaceous

Herbaceous

Ecology

Supports

Supports bees

Bees

Supports butterflies and moths

Butterflies & Moths

Supports humingbirds

Hummingbirds

Providing

Provides nectar source

Nectar source

A favorite for native bumblebees, hyssop is a high-value plant for pollinators, also attracting hummingbirds and butterfies. 

Habitat

Typically found in

open woods, prairie, meadows

Frequently found in open grassland, moist meadows, open woods and woodland edges.

In the Garden

Growing Conditions

Moisture

Dry conditions

Dry

Average conditions

Average

Light

Full sun

Full sun

Partial sun

Part sun

Partial shade

Part shade

Soil

Average garden soil, Sand, Loam

Propagation

Via

Seeds

Seeds

Division

Division

Self-seeding

Self-seeding

Sowing Recommendations

Sow seeds in pot

Sow seeds in pot

Sow seeds in Spring

Spring planting

High or easy germination

Landscape

Use for:

Back of bed placement

Back of bed

Landscape feature

Landscape feature

Low maintenance gardening

Low maintenance gardening

Middle of bed placement

Middle of bed

Mass planting

Mass planting

Growing Tips

  • One of the easiest plants to grow, with high germination rates and vigorous growth.

  • Adaptable to a variety of conditions, but doesn't like heavy clay.

  • Will spread into a clump and self-seed, though extra seedlings are easily managed by pulling. 

  • Suggested spacing is 45 cm.

Description

Giant hyssop is a medium-to-tall bushy plant that fills in space well in the garden and produces many purple flower spikes. It's an easily grown, versatile plant that grows in full sun or light shade and will adapt to a variety of moisture conditions, making it an accelent choice for new and experienced gardeners alike. It is likely to form a busy hub for pollinators in the garden. It also makes a good cut flower.

Mature plants produce a very large number of seeds, which are easy to collect non-destructively. When stalks turn brown after flowering, most of the seeds are likely to be ready. Tip the stalk upside down over an open paper envelope or paper bag and give it a light shake. Mature seeds will spill out (often by the hundreds), while any maturing seeds remain. If few seeds shake out, try again in a week or two.

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