Agastache foeniculum

Blue Giant Hyssop

Blue Giant Hyssop (Agastache foeniculum) is an exceptionally cold-hardy Hyssop that blooms for many months with smoky-blue flowers held above attractive, aromatic foliage. It is native to the Mid-west.
Zones4 - 8
Advantages
Deer Resistant
Attract Butterflies
Rabbit Resistant
Fragrant
Light Requirements
Full Sun
Annual Rainfall
10 to 20"
20 to 30"
30 to 40"
Mature Plant Size30-36" tall 15-18" wide
Bloom TimeMid to late summer
ShippingNo longer available this season. Learn More…
SizePlant - 5" Pot
SKUHC015393

USDA Hardiness Planting Zones

To determine if a plant is sufficiently cold hardy, the USDA created numbered zones indicating winter low temperatures; the lower the zone number the colder the winter.

  • If the coldest winter temperature expected in your area is -15°F (zone 5) then any plants rated zones 3-5 will survive the winter temperatures in your area.
  • If you live in very warm winter areas (zones 9-11) plants with zones 3-4 ratings are not recommended. The lack of freezing winter temperatures do not provide a time for winter dormancy (rest).

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Per Plant - 5" Pot
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SKU
HC015393

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Details
Agastache foeniculum (Blue Giant Hyssop), a native to the northern tier states and Canada, this exceptionally cold hardy Hyssop blooms for many months with smoky-blue flowers held above attractive, aromatic foliage. An outstanding perennial for attracting bees and butterflies with its nectar-rich flowers, Agastache foenicuum is highly recommended for gardeners in the moister eastern half of the country, where more xeric Hyssops (Hummingbird mints) like Agastache rupestris and Agastache cana will struggle.

More Information
SKU
HC015393
Item Package Size
Plant - 5" Pot
Common Name
Blue Giant Hyssop
Botanical Name
Agastache foeniculum
Zones
4, 5, 6, 7, 8
Light Requirements
Full Sun
Flower Color
Blue
Mature Height
30-36" tall
Mature Spread
15-18" wide
Bloom Time
Mid to late summer
Ships As
Potted Plant
Soil Type
Average Soil
Soil Moisture
Drought Resistant / Waterwise, Average
Amount Of Rain
10 to 20", 20 to 30", 30 to 40"
Advantages
Deer Resistant, Attract Butterflies, Rabbit Resistant, Fragrant
Ideal Region
Anywhere In The US, Northeast, Midwest, West, Southwest, Pacific Northwest
Planting Time
Spring / Summer, Fall
Native To
North America
Ships To Canada
No
Planting Guides

Tips for growing Agastache

Agastache are sun loving plants with aromatic foliage and flowers. They bloom from mid-summer into early fall and are resistant to rabbits and deer.

Agastache need lean, well-drained soils, prefer gravel mulches, and appreciate deep but infrequent watering after their second growing season

  1. Provide a fast draining soil that's naturally low in fertility, Don't plant into clay soils.
  2. Plant in full hot sun.
  3. Just a few handfuls of compost in the planting hole is enough. Don't plant into a rich, highly amended soil..
  4. Fertilize the Agastache just once in fall with Yum Yum Mix and Planters II.
  5. New transplants need regular irrigation their first growing season to establish themselves. Watering can be reduced greatly during the second growing season when the plants have matured.

To improve winter-hardiness, and encourage re-seeding, leave the stems intact over the winter. In mid-spring, remove old stems just above the new foliage, about 4 or 5 inches above ground level.

If your conditions don't lend themselves to growing Agastache in your garden, they do well planted in containers.

More in-depth guidance for growing Agastache: Agastache Growing Tips, Agastache: Super-Stars of the Perennial World Part 1, and Agastache: Super-Stars of the Perennial World Part II.


View more Planting Guides, or download our complete Planting Guide for tips on caring for your plants when you receive your order, as well as planting instructions for Perennials, Spring-Planted Bulbs, Fall-Planted Bulbs, Cacti & Succulents, Xeric Plants and more.
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