Giant Hyssop spp. (Agastache)

by Rebecca Hutchings

Why do “Nova Native” gardeners love to plant this perennial? Let me count the ways! It is an attractive, upright clump-forming plant with graceful and long staying flower spikes and a neat habit. As a member of the mint family (Lamiaceae) the leaves look a bit like catnip, but larger. The plant is hardy in USDA Zones 5 to 9, where it is considered late flowering with continual blooms scattered along spikes from June thru early September.

 

It works best in a generally sunny well-drained location. Hyssop is tolerant of drought and will thrive in the kind of clay-loam soil we find in the mid-Atlantic region.

 

When Giant Hyssop leaves are crushed they have a minty-licorice scent that has been used in tea, seasonings and jelly. If you are not finding native Hyssop among your nursery’s perennials try looking in the herb section.

 

Hyssop is considered a tall strong (almost giant?) plant for the back of a perennial boarder or next to a fence. Its abundant nectar is always in demand in native plant / butterfly / pollinator gardens.

 

The follow three species are commonly seen in Virginia:

Blue Giant Hyssop (Agastache foeniculum) (picture above) is a widely sold form and is commonly labeled as Anise Hyssop. This variety is native to the mid-west and Canada so it is not listed in the Flora of Virginia. It grows 2 to 4 feet tall and will spread to be 3 feet wide. The flower spikes (calyx) are 3-6 inches long and can range from a blue violet to bright lavender. (Garden centers regularly sell Anise Hyssop cultivars such as ‘Blue Fortune’ and ‘Premium Blue’.) Photo: Sally and Andy Wasowski, Lady Bird Johnson Wildflower Center.

Purple Giant Hyssop(Agastache scrophulariifolia) is a native plant of the eastern US, and Purple Giant Hyssopwas historically found around the Piedmont. It can grow up to 6 feet tall in loamy soils. The calyx can range from white to purplish or pink. Photo: William S. Justice, Hosted by the USDA-NRCS PLANTS Database.

 

 

 

Yellow Giant Hyssop(Agastache nepetoides) is also an historical native to Virginia.  It is more shade tolerant preferring a more fertile and moist soil. The calyx can range from pale greenish yellow to yellowish white. The Yellow Giant does not

yellow giant hyssopbranch as much as the other varieties. Photo: Thomas G. Barnes, hosted by the USDA-NRCS PLANTS Database.

 

 

 

 

Native Hyssop plants will spread (but not aggressively) by rhizomes and possibly self-seed in sunny growing conditions. After the initial bloom, if you consider it to be too leggy you can cut it back by 1/3 and it will get bushier and re-bloom. A wire frame support can be used to help prop up the plant so a heavy summer rain does not cause the spikes to flop over.

 

The plant’s flowers are cross-pollinated by bees seeking nectar or pollen. Frequent visitors include honeybees and our black and gold bumblebees (Bombus auricomus and Bombus pensylvanicus). Researchers have identified over 14 different varieties of butterfly’s, skippers and moths visiting the flowers.

 

Deer don’t seem to like Hyssop’s leaves and the anise foliage scent may even deter aphids, making it a good choice to plant in a butterfly garden.

 

The graceful flowers spikes are attractive in fresh cut or dried floral arrangements. Mulch the plant if you decide to keep the leaves and flowers in place overwinter. This will increase the plant’s cold hardiness and add interest to your landscape. Cut back fairly hard by mid-spring and without much more work get ready to share its beauty with your garden visitors. Any of these Hyssop species (Agastche) would be a highly valued plant in your garden for lots of reasons.

 

References:

 

USDA, NRCS. 2016 The PLANTS Database:

 

Flora of Virginia / Weakley, Ludwig, Townsend.  www.floraofvirginia.org

 

Digital Atlas of the Virginia Flora:

 

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