Betty Jakum
Adams County Master Gardener
Gardeners may never have heard of this plant that has been chosen Perennial of the Year for 2025. Its name is Clustered Mountain Mint (Pycnanthemum muticum), and it is one of eight species of Mountain Mint found in Pennsylvania. There are about twenty species in total, differentiated by their leaf structures ranging from heart-shaped to needle-shaped. Most species can be found growing in the Eastern and Central United States.
This plant’s name is somewhat of a confusing misnomer, as it does not readily grow in mountainous regions and is not a true mint like peppermint or spearmint. According to the publication, "Mother Earth Living", one possible reason for the name can be traced to someone whose name is familiar in Pennsylvanian forestry. French botanist Andre Michaux (Michaux State Forest), trekking through the state’s woods in the late 1700s in search of useful plants came across some vigorous knee-high masses of lovely-scented plants he called Mountain Mint. Today, this common name is still used for all the native species of the genus Pycnanthemum.
The term "Mint" sometimes scares gardeners away from planting this wonderful pollinator. Like all plants in the mint family "Lamiaceae", Mountain Mint can be identified by its square stem and aromatic leaves. Yet there are significant differences from the non-native mints like spearmint and peppermint that we’re more familiar with.
Mountain Mint is a native plant that respects boundaries. While non-native mints are best grown in containers to limit their aggressive spreading, Mountain Mint is fairly well behaved. It is easy to grow and maintain. It spreads by rhizomes that form in groups due to its natural clumping habit. It is easy to control by pulling up unwanted growth or pruning rhizomes in the spring. Unwanted clumps can be discarded or better yet shared with others interested in supporting pollinators.
The densely packed clusters of tiny flowers are covered with fine hairs that make the leaves appear powdery white. Mountain Mint provides a long bloom period beginning in June. Blooming can even be extended if the plant is periodically cut back. It blooms till September, providing pollinators with a continuous and critical source of late summer food. It is resistant to most common pests and diseases, making it a low-maintenance addition to the garden. Deer, rabbit, groundhogs, mice, and voles ignore it because of its strong fragrance and taste.
Mountain Mint thrives in full sun and partial shade in well-drained soil. It prefers moist soil but can tolerate drier conditions once established. It can grow in a variety of soil types including clay, loam, and sandy soil, preferring a slightly acidic to neutral pH between 6.1 and 7.3. Mountain Mint is hardy in Zones 3 to 8 where it will grow 2 to 3 feet tall. It can tolerate temperatures down to minus 20 degrees. It tends to populate lowland environments like meadows, fields, and sunny forest clearings.
Many insects are attracted to Mountain Mint including various species of predatory and parasitoid insects that prey upon pests. A study conducted at Penn State found Mountain Mint to be a top attractor of pollinators. At least 78 insects, including native bees, honeybees, butterflies, moths, beetles, and solitary wasps play an important role in pest control and pollination. Last summer, a Mountain Mint cluster in my pollinator bed was practically covered by non-aggressive Black thread-waisted wasps working its flowers.
Mountain Mint is one of Pennsylvania’s Keystone Plants. Keystone Plants are native plants that play a disproportionately large role in supporting the diversity and abundance of other species in the ecosystem. They are often essential for the food web, providing crucial resources for insects, pollinators, and other wildlife. If removed, the ecosystem can suffer significant declines in biodiversity and overall health.
Mountain Mint will never find itself included on a list of the 10 Best Eye-Candy Flowers in the marketplace. Except for a slight blush of pink or lavender, its tubular flowers blend almost seamlessly with its prevailing light green color. Rather, its abilities lie in areas where it takes "more than just a pretty face" to get the job done.
Many sources tout the benefits of Mountain Mint tea. It’s known for its refreshing flavor, soothing properties, and potential health benefits. It’s a deterrent to many destructive critters because of its minty taste and unpleasant (at least to the critters) scent. Mountain Mint is also an effective insect repellent. A handful rubbed on pant legs deters chiggers and ticks and some crushed leaves stuck in a hat keep annoying gnats away from the face.
Mountain Mint’s greatest contribution is its superiority as a marvelous pollinator. Unfortunately, in the midst of declining numbers of pollinators and of pollinator plants, we all have a part to play in making food sources for insects as plentiful as possible. Dr. Doug Tallamy, a professor in the Department of Entomology and Wildlife Ecology at the University of Delaware and a strong advocate of sustaining wildlife with native plants, believes we are all responsible for our "little piece of the earth." He estimates that the worldwide population of anthropoids, chiefly insects, has declined by 45% since pre-industrial times. Without insects, many of the higher species, including mammals like us, would lose all or a large part of their diets. "’The little things that run the world are disappearing,’ he says. ’This is an ecological crisis that we’re just starting to talk about.’"
A recent telephone survey of local greenhouses found that 6 out of 10 had Mountain Mint for sale. Of the 4 that did not, 2 seemed interested in learning more about it. The next time you’re out flower shopping, make a point of looking for Mountain Mint. If shops have it, good for them. Buy a plant or two. If they don’t, ask them to supply plants for future purchase. It’s such a small thing that we can do to make the world a better place for all of us, insects included.
Read other articles on growing herbs
Read other articles by Betty Jakum
