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Pycnanthemum flexuosum (Appalachian mountain mint)
Species Distribution Map: Click to enlarge
Map Color Key © 2013 BONAP

Pycnanthemum flexuosum

Appalachian mountain mint

(syn. Koellia hyssopifolia)

An aromatic, summer blooming, herbaceous perennial that produces silvery white, globular flowers on sturdy, upright stems. Blooming over a long period, flowers are prominently displayed above clean green foliage from summer into fall. A good soil stabilizer, this species spreads moderately via underground stem. Foliage develops an attractive red tinge in autumn. A larval host plant for the Gray Hairstreak Butterfly. Incorporate along the perennial border, rain garden, or near the vegetable garden to entice pollinators.

SIZE
Pycnanthemum flexuosum LP50 - 50 per flat Availability
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Height

2-3 Feet

Spread

3-4 Feet

Spacing

12 Inches

Bloom Color

White

USDA Hardiness Zone 6-8

Appalachian mountain mint Interesting Notes

Pycnanthemum flexuosum is an aromatic, summer-blooming, herbaceous perennial that produces silvery white, globular flowers on sturdy, upright stems. Blooming over a long period, flowers are prominently displayed above clean green foliage from summer into fall. Appalachian mountain mint is a good soil stabilizer, this species spreads moderately via underground stem. In the fall, the foliage develops an attractive red tinge in autumn. The plant grows about 2-3’ tall and 2-3’ wide when fully mature.


P. flexuosum originates from the southeast along the Appalachian Mountains, from Virginia to Florida to Alabama. Preferring full sun to part sun in moist to average garden soils, it can be found in upland prairies, pastures, meadows, open woodland and roadsides in the wild. Appalachian mountain mint spreads slowly by rhizomes. Its slower tendencies make it a much better behaved mountain mint in the garden than others in the genus.


A member of the mint family, the aromatic oils in the foliage make Pycnanthemum very deer and rabbit resistant. Mountain mint contains pulegone which is a natural insect repellant. It is a larval host plant for the Gray Hairstreak Butterfly and the flowers are covered in wasps, bees, flies, butterflies, and skippers as it blooms throughout the summer. Good to incorporate along the perennial border, rain garden, or near the vegetable garden to entice pollinators and best planted in large clumps where insects can easily move from flower to flower. The strong root systems make a tough soil stabilizer that is great for slopes and streambanks.

Good Substitutions

short-toothed mountain mint Pycnanthemum muticum
slender mountain mint Pycnanthemum tenuifolium

Key Characteristics & Attributes

Full Sun
Full Sun
Part Sun
Part Sun
Moist
Moist
Pollinator-friendly
Pollinator-friendly
Deer Resistant
Deer Resistant
Cut Flower
Cut Flower
Fragrant
Fragrant
Summer
Summer

Additional Information

Soil Moisture Needs
Average
Dry
Green Infrastructure
Bioretention/Rain Garden
Meadow/Prairie
Woodland
Wetland Indicator Status
Falcutative Wetland (FACW)
Plug Type
Landscape Plug™
Attributes
Native to North America
Season of Interest (Flowering)
Fall
Late Summer
Propagation Type
Vegetative