The Pollinator Haven Garden at the N.C. Cooperative Extension- Lee County Center is always abuzz these summer days. More than 40 different plant species are in flower during the month of August, but there is one plant that stands above them all when it comes to the number of different species it attracts: the mountainmint. The Pollinator Haven Garden is home to five species of mountainmint, with the clustered mountainmint, Pycnanthemum muticum, being the crowd favorite. This is an easy plant to grow in your home garden to add diversity to your landscape and attract local pollinators.

The Mountainmints

Mountainmints are in the genus Pycnanthemum and are in the Lamiaceae, the mint family. Unlike the mints we put in our juleps, which are from the Mediterranean, the mountainmints are native to Eastern North America, though the greatest diversity is in the Southeastern states. There are several wide-spread species, and a few rare species only found in a few places in the mountains or along the coast plains. What makes them distinctive is their unique dense heads of flowers that produce dozens of small flowers over several weeks in the spring and summer, depending on the species.

Another distinctive feature is their minty aroma, which draws humans and insects alike. The clean, refreshing scent easily comes off after gently brushing the plant. In recent years there has been an interest in understanding the chemicals that make this unique scent. An Alabama study identified 42 odorants in P. muticum, and several studies have identified the essential oils in the plants. There are a few essential oils that have been identified from mountainmints, but pulegone is the most abundant in the plants. This is a naturally occurring organic compound, found in the essential oils of other mint relatives. It has a distinct minty aroma and is used in flavoring, perfumery, and aromatherapy. While it has some potential benefits like mood enhancement and relaxation, it should not be eaten, due to its metabolism into menthofuran, a hepatotoxin.

How to Grow Mountainmint

There is a mountainmint for every niche in your garden! Some prefer full sun, some don’t mint some shade. Some species will spread quickly and some will gently expand over several years. The thing that is most endearing about this spreading habit is that, unlike the mint herb which can be hard to remove after its spread around, mountainmints can be easily pulled up. Some can be three or four feet tall, and some are only about one foot tall. They come in dense textures with white bracts (colored leaves below the flowers) or fine textures, giving an airy look to a garden bed.

In Lee County, the clustered mountainmint, Pycnanthemum muticum, is arguably the easiest one to grow and does well in full sun with well-draining soil. It flowers for more than two months in the summer and the white-colored bracts give the plant a glowing quality. It is a good foil to brightly colored flowers.

The Virginia mountainmint, P. virginianum, has a beautiful leaf texture with an olive green-grey color. The flowers are much larger than the clustered mountainmint, though they are still small, and the flower period is shorter. It also has a more formal, upright habit and doesn’t spread as quickly, compared to the clustered mountainmint either.

The frilly texture of the narrow-leafed mountainmint, P. tenuifolium, makes a great filler for your perennial border, but the gentle flowering habit packs a powerful pollinator punch. The flower period isn’t very long, but it is a crowd favorite when it is flowering. It will gently tuck itself in around other plants and contrasts nicely with the dense textures of many of our favorite pollinator plants.

Finally, the hoary mountainmint, P. incanum, is a beastly, flowering machine with wide, white heads of flowers. It can get very tall, though it doesn’t spread as fast as the clustered mountainmint. The texture and color of this plant make a bold statement in a border and attract a lot of insects.

What You Might Expect To See

The best part of the mountainmints is the diversity of insects they attract, and every species is preferred by a different mixture of insects. The research about insect richness varies wildly on which species is preferred by the most species, and really depends on where the plants are and what else is around.

In one study on clustered mountainmint, more than 85 different species were found on this species (Ortiz, Coster, and Ruppel 2024)! The same study identified 43 different species on P. tenuifolium flowers. Another study looked at whorled mountainmint (P. verticillatum) and noted it attracted a diverse more than 19 different families of pollinating insects, more than eleven families of beneficial insects, and more than 15 families of herbivorous insects (Harris, Poole and Pennisi 2022).

Needless to say, you are going to see a mixture of bees, flies, wasps, and butterflies, just to name a few. No need to be alarmed about the cloud of insects (not even the two-inch long wasps). They are going to be too busy gathering nectar and pollen to worry about you. Instead, they will continue to increase the insect biodiversity of your garden year after year. This diversity not only can be interesting to watch, but can also add other benefits to your garden, such as pest control and pollination services for your fruits and vegetables!

Amanda Bratcher is the Horticulture Agent for North Carolina Cooperative Extension in Lee County.