Pycnanthemum - Mountain Mint – Pollinators’ Delight

If Eastern US native pollinators have a favorite plant, it is without contest Pycnanthemum. Commonly called “Mountain Mint”, this family of plants is native to much of Eastern and Central North America. It can be found naturally in a range of habitats from mountain ridges to forests, from dry prairies to swampy bogs, and every biome in-between.

While Mountain Mint’s flowers are not very large, they are numerous and rich in nectar, and they open over a long period to extend the potential feeding time for pollinators. A Mountain Mint in bloom is in constant motion thanks to attention from native bees, honeybees, butterflies, solitary wasps, and beetles.

In the garden, Mountain Mint needs just the right spot. Not because it’s picky – actually, it can grow in most soil types – but because it is a rhizomatous spreader. Mountain Mint is perfect for wildlife gardens, meadows, roadsides, and other naturalized areas where it can stretch out freely. It can be grown in more manicured gardens if it is placed in an area that limits its spread, or planted in a large, buried container that will block the rhizomes. Some varieties spread more than others.

The leaves of Pycnanthemum species have a wonderful, minty fragrance and are often used in teas. The smell is not for everyone: deer and rabbits almost always turn up their nose and pass it by for other potential meals.

Pycnanthemum flexuosum, also known as Appalachian Mountain Mint, has the smallest native range, from Virginia to Mississippi.  It is naturally found in wet sites, such as swamps, bogs, bottomland forests and pine barrens. It is prettiest planted in full sun and moist to wet soil, but it will tolerate drier soil and drought.

Pycnanthemum flexuosum has oval, toothed opposite leaves on square stems that are covered with fine white hairs. The leaves may take on a reddish or purple cast in cool weather.  The plants are upright, 2-3’ tall, and produce dense cymes of fuzzy white to pale lavender blooms in late summer to early fall.  Its rhizomatous spread is slower than some of the other Mountain Mints.

Pycnanthemum muticum, also known as Clustered Mountain Mint, has a larger native range from Texas to Michigan, east to Maine and south to Georgia.  It is naturally found in bogs, savannas, and other low areas, as well as mountain ridges and balds.  Pycnanthemum muticum prefers a sunny, wet to moist, well-drained site, but will tolerate part shade, clay soil, heat and drought. 

Clustered Mountain Mint is a 2’-3’ tall, upright plant with silvery green, oval leaves that have sharp tips.  Its bloom clusters consist of tiny white to lavender flowers that have a silvery cast. The individual blooms open gradually over a period of six to eight weeks in late summer to early fall. 

A 2013 study at Penn State Extension Service showed that Pycnanthemum muticum is the most popular pollinator species, being visited by at least 78 insects in a few minutes time.  It is a relatively quick spreader with shallow rhizomes that may travel across the soil surface as well as below.

Pycnanthemum tenuifolium, also known as Narrowleaf (or Slender) Mountain Mint, has the widest natural range, found from Texas to Nebraska, northeastward into Canada and southeast to Florida.  It is endemic to dry, open woods, dry prairies, and fields as well as along roadsides, streams and in wet thickets. It prefers full sun to part shade and, unlike most Mountain Mint, dry to medium moist soils.

 Pycnanthemum tenuifolium has very fine, almost needle-like leaves on hairless, erect, branched stems that are 2’-3’ tall.  Its white flowers with two purple spots are produced in terminal clusters and open over an extended period, from middle summer into early fall, slightly earlier than P. muticum.  Like the other Mountain Mints, it spreads via rhizomes to form attractive colonies.

Pycnanthemum virginianum, also called Virginia or American Mountain Mint, is found from North Dakota south to Oklahoma and Mississippi, and northeastward into Maine and Canada.  In the wild, plants are typically found in the moist soil of meadows, swamps, stream sides, and pond edges.  It prefers full sun to part shade and moist to wet soil, but it is tolerant of drier soils and drought.

Pycnanthemum virginianum grows 2’-3’ tall and has narrow, toothless leaves on multi-branched plants. The terminal clusters of small white blooms are produced in abundance and gradually open from middle to late summer or early fall.

Any garden could benefit from a well-placed Mountain Mint to attract pollinators. Pair it with other natives like Bee Balm, Gay Feather, Switch Grass, Little Bluestem, Goldenrod or Black-Eyed Susan for a natural wildlife flowerbed. Or tuck one into a large container on your deck, patio, or beside raised vegetable beds.