Mountain mint is a NC native perennial in the Lamiaceae (mint) family found primarily in the coastal and Piedmont areas of the state. The genus name Pycnanthemum comes from the Greek word p yknos means dense and anthos which means flower referring to the clustered tufts of white flowers that adorn the plant in the late summer. The speices name flexuosum is Latin for pliant and is likely in reference to its bendable square stems. Mountain mint prefers rich loamy moist soil with good drainage in full sun to partial shade. Wihle it grows on a variety of soils types and pH conditions, in its native habitat, it is found growing on alkaline soil. It will tolerate drier conditions once established. Unlike other members of the mint family, mountain mint grows slowly by underground rhizomes. It forms a clumping pattern on erect stems with fragrant narrow green foliage 2 to 3 feet tall and 1 to 3 feet wide. Plants can be easily divided to propagate and should be every other year to maintain the best appearance. In late summer it is topped by rounded clusters of white to lavender tubular flowers. The flowers attract pollinators including bees, butterflies and wasps. The dried capsule fruits provide interest in the winter landscape. It is resistant to browsing by rabbits and deer. Plant in the middle of a border in a sensory, pollinator, or native garden and enjoy all the wildlife it will bring to the landscape. They work well along a woodland margin, in a rain garden or to help prevent erosion along a slope. Or mass plant it in a meadow or other naturalized area or near a pond or streambank. The light green leaves contrast nicely with purple leaved plants. Because of its strong upright appearance plan to plant shorter plants in front. Insects, Diseases, and Other Plant Problems: No serious problems. More information on Pycnanthemum .
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; High Organic Matter; Loam (Silt); Sand; Shallow Rocky
Soil pH
Acid (<6.0); Alkaline (>8.0); Neutral (6.0-8.0)
Soil drainage
Good Drainage | Moist | Occasionally Dry
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 3 ft. 0 in. | Width: 1 ft. 0 in. - 3 ft. 0 in.
Growth rate
Slow
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Clumping; Erect; Spreading
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Opposite
Leaf shape
Elliptical; Lanceolate
Leaf margin
Crenate
Leaf value
Fragrant
Leaf size
1-3 inches long
Hairs present
No
Leaf detail
Thick oval to lance-shaped green leaves 2-2 1/2 inches long with short petioles, toothed margins are red-tinged in fall. The fragrance is reminiscent of spearmint.
Fall color
Red/Burgundy
Flower color
Purple/Lavender; White
Flower value
Fragrant
Flower form
Cyme
Flower shape
Tubular
Flower size
< 1 inch
Flower detail
Terminal dense globular clusters which are 1 1/2" across of tiny 1/4" white to lavender tubular flowers with purple spots. Each flower has a calyx composed of 5 off-white sepals that protects the flower bud and then supports the flower. Once the flowers fade the sepals remain and give the globular head a fuzzy appearance. Blooms late summer. for about 2 months.
Bloom time
Summer
Fruit type
Capsule
Fruit detail
Capsules are dry, attractive in the winter
Stem color
Green
Stem detail
Branched green square stems
Wildlife & Ecology
Native status
Native
Origin
Southeastern U.S.A
Distribution
AL, FL, GA, MS, NC, SC, VA
Wildlife value
Attracts pollinators including bees, butterflies, moths, and wasps. Swallowtail butterflies nectar at the flowers. A larval host plant for the Gray Hairstreak butterfly and Wavy-lined Emerald (Synchlora aerata).
Attracts
Butterflies; Moths; Pollinators
Host plant for
Gray Hairstreak butterfly and Wavy-lined Emerald (Synchlora aerata)