Mountain Mint – Pollinators’ Delight

Pycnanthemum or Mountain Mint is a perennial genus that is an absolute favorite plant for a wide range of pollinating insects.  While their blooms are smallish and not showy, they are numerous, open over a long period of time and provide plenty of nectar.  Visitors to Mountain Mint include bumblebees, honeybees, solitary wasps, tachinid flies, syrphid flies, beetles and butterflies.  A Pycnanthemum in bloom is in constant motion with the hordes of visiting insects. 

All Pycnanthemum species are North American natives. Their leaves have a wonderful mint fragrance and may be used in teas. Their strongly aromatic foliage is not bothered by deer or rabbits.  Due to their rhizomatous habit, they make great plants for erosion control, but plant in a buried container if you wish to limit the spread.

There are many species in this genus.  We carry 4 of them: Pycnanthemum flexuosum, P. muticum, P. tenuifolium, and P. virginianum.  These species vary in their native range, leaf size and shape, bloom time, and natural habitat, but all are easy to grow. 

Pycnanthemum flexuosum, also known as Appalachian Mountain Mint, has the smallest range of these, from Virginia to Mississippi.  It is naturally found on 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.  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 it 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 of these Mountain Mints is worthy of a spot in your garden. Pair them with other natives, such as Bee Balm, Gay Feather, Switch Grass, Little Bluestem, Goldenrod or Black-Eyed Susan for a natural planting.  Or, tuck one into a container on your deck or patio or in the corner of your vegetable garden to attract pollinating insects to increase your yields.