Pycnanthemum muticum, also known as Clustered mountainmint, blunt mountainmint or short-toothed mountainmint is a tough and adaptable perennial native to meadows and open woodlands across much of the eastern United States west to Texas.
It is not a true mint (Mentha spp.) but belongs to the same family and has similarly scented leaves. A must-have for pollinator gardens, heads of tiny white to light pink blooms attract butterflies, wasps, and bees from July to September. The inconspicuous flowers are upstaged by surrounding silver bracts, which give the illusion of frost in summer and persist for months. Clustered mountainmint has no serious disease issues, and its aromatic foliage is unpalatable to deer and rabbits.
Branched, vertical stems grow two to three feet tall and form a dense, weed-suppressing clump. Clustered mountainmint spreads by underground rhizomes and can be aggressive in moist conditions, though it is not invasive to the degree of true mints.
Plant clustered mountainmint in an area where it can freely naturalize and mingle among other plants. Its silver sheen plays well with other flower colors and contrasts wonderfully with dark foliage.
Companions include black-eyed Susans (Rudbeckia spp.), bee balms (Monarda spp.), blazing stars (Liatris spp.), Joe Pye weeds (Eutrochium spp.), and native grasses.
Plant data provided by PPA
USDA Zones 4 to 8
Canadian Hardiness Zones 3 to 7
Light
Full sun to part shade
Size
24-36 inches (60-100 cm) tall; spreads widely by rhizomes
Origin
Eastern United States, west to Texas
Soil
Prefers medium to high moisture, fertile, well-draining soils. Tolerates clay soils. Less tolerant of drought than most other mountainmints.
Maintenance
Clustered mountainmint can spread aggressively, especially in wet soils. Rhizomes are easy to control by cutting them to the desired size with a spade and pulling the shoots by hand in spring. Seed heads may be left until early spring for winter interest. Tolerates heat and drought once established. No serious pest or disease issues.
📸: Chicago Botanic Gardens