Total Guide to Blunt Mountain Mint (Pycnanthemum muticum)


blunt clustered mountainmint plant

Blunt Mountain Mint is one of the most ecologically important flowering plants you can grow in your yard due to the variety of species, and sheer number of pollinators that it attracts. It’s gentle white to silver colors allow it to look great in any garden setting, and it has other characteristics that make it an attractive residential friendly native plant. I’ve grown this plant for years, and can share with you all the info you need to know to successfully grow this wonderful flower in your garden.

How this article is organized:

What is Blunt Mountain Mint

Blunt Mountain Mint is a clump-forming herbaceous wildflower native to the Eastern United States. Scientifically known as Pycnanthemum muticum, it grows 2-3′ tall in Full sun and medium-moist soil. Blooming for approximately four to six weeks in July and August, it will attract huge numbers of pollinators that seek out it’s nectar.

The value of Blunt Mountain Mint to pollinators cannot be overstated. You will discover new species of pollinators that you never knew existed when observing this plant in full bloom! It is one of the busiest plants a buzz with activity in my vast gardens. Mountain mint is a must have for anyone who wants to garden for wildlife.

True to it’s name, the leaves have a strong minty aroma when crushed or torn, which also makes it one of the most deer resistant plants you can grow. A tea can also be made from the leaves.

Facts

  • Is a favorite flower of bees, butterflies, and other pollinating insects.  This plant has a very high value for pollinators.
  • Contains a natural insect repellent, pulegone
  • Slowly spreads via rhizomes, but easy to control
  • Deer and rabbit resistant
  • Has a long blooming period of 4-6 weeks
  • Is attractive even after flowering, into the winter
  • Blunt Mountainmint is hardy from USDA zones 4-8.  Check your USDA zone here
  • It shares many of the same characteristics as other species of Mountain Mint

Native Range of Blunt Mountain Mint

A native plant, Blunt mountain mint has a native range from Texas to Illinois, then East to the Atlantic Ocean and New England.

Source [1]

Reference Table

Scientific NamePycnanthemum muticum
Common Name(s)Blunt Mountainmint, Short Toothed Mountain Mint, Clustered Mountain Mint
Native Range, USDA ZoneEastern United States. USDA Hardiness Zone zones 4-8
Bloom TimeJuly-August
Bloom Duration, Color4 weeks, white
Height2-3′ (60-90 cm)
Spacing / Spread2′ (60 cm)
Light RequirementsFull sun, partial shade
Soil TypesLoam, clay.
MoistureMoist to medium moisture
Fauna Associations / Larval HostsNumerous species of bees/butterflies and other pollinating insects visit. Not a larval host.
Sources [1] [2] [3]

What are the Benefits of Blunt Mountain Mint

Pollinators

It is truly amazing just how many pollinators, and how many different and unique species of pollinators Blunt Mountain Mint will attract. I see different species of bees, pollinating wasps, pollinating flies, and other pollinating insects on Blunt Mountain Mint that I find nowhere else in my ever expanding gardens. And I have a lot of species! But I am continually amazed by what Blunt Mountain Mint can attract.

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This is a small sample of what you can expect should you grow Blunt Mountain Mint.

Versatility

The white bracts that surround the flowers give gardens a whitish hue that is beautiful. It gives it the ability to pair with any other flower and make a nice display.

Erect

Blunt Mountain Mint stands straight up and erect when planted in full sun. Wind storms never knock it over, and it doesn’t seem to ‘reach’ for the sun if planted in partial shade.

Naturalizing – can fight invasive plants

If you are fighting invasive plants, or need something to quickly naturalize an area, Blunt Mountain Mint can help you do just that. It’s spreading nature make it a good candidate to seek out vacancies in the soil, which prevents other non-native plants from doing so. It’s erect nature also means that it generally doesn’t get shaded out.

Grow and Care for Blunt Mountain Mint

Sunlight Requirements

Blunt Mountain Mint will grow best in full sun, which is at least six hours of direct sunlight per day. But it can tolerate partial shade. I’ve been moving new transplants to an open wooded area behind my house, as it can establish, maintain, and expand it’s presence over invasive plants.

Soil Requirements

It can grow well in sandy loam to clay loam. Will grow best in fertile soil that drains well. But my experience has been that this plant can grow almost anywhere. In my own yard, I’ve had great success on an exposed slope of over-compacted infertile sandy loam.

Moisture Requirements

Blunt Mountain-Mint prefers moist to medium-moist soil that drains well. Most of the specimens I’ve grown have done great on slopes.

Maintenance

The primary maintenance you will have with Blunt Mountain Mint is to prune the clump each Spring to it’s desired size. If grown in the open, it will form a circular clump that will expand every year unless pruned.

The rhizomes will grow radially outwards, but this is an easy chore in the Spring that takes about 10 minutes to perform. Just take a spade and chop the circle down to the size you want the plant to be, and then pull up the shoots by hand that are beyond that circle. You can replant the extra shoots, or discard/compost them.

Also, in Spring, you can cut down the previous years stalks to ground as part of your fall-garden-clean-up.

Fertilizer

Blunt Mountain Mint will not require any supplemental fertilizer.

Video Grow and Care Guide to Blunt Mountain Mint

How to Grow Blunt Mountain Mint from Seed

Growing Blunt Mountain Mint from seed is fairly straight forward.  It doesn’t require any stratification, but needs light to germinate. 

So to grow Clustered Mountain Mint from seed you just need to sprinkle seed in a disturbed area in early Spring.  Or just direct so in pots and keep moist, letting them get morning sun and afternoon shade.

If you grow other flowers from seed and Winter Sow, you can simply Winter Sow Blunt Mountain Mint as well. Just sprinkle the seed on top of the soil, and set your jug outside where it will get morning sun / afternoon shade.

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Blunt Mountain Mint Seedlings

Once you have germination, thin to the desired number of plants.  Transplant seedlings once they are several inches tall into their final location.  Then just maintain soil moisture throughout the first year.  Alternatively you can plant your transplants in the fall, and the roots will establish themselves during the winter.

clustered mountainmint in spring
This photo was taken about 1 month after emergence in Spring

Propagating Mountain Mint through Division

If you have an established plant, or know of someone who does, then Blunt Mountain Mint is extremely easy to divide and get free plants!  Actually it is probably the best way to propagate the plant. If you separate some shoots in April, you can have several blooming stalks by August (I’ve done so many times).

In early Spring, shortly after the plant has emerged you can safely divide them.  You can pot-up the transplants, or replant entire clumps.  It is very important to do this in Spring, as the soil is cool and moist. This helps the plant reestablish it’s roots without being subjected to high temperatures/sun.

Process to divide Mountain Mint is as follows:

  1. Gather up a spade, small handheld garden shovel, handheld pruning sheers, and a pot or bucket to hold the new plants.
  2. Rake up any mulch around the plant, so that you have easy access to the dirt.
  3. Use the spade to stab through the soil 4-6 inches away from the area you want to divide.  Doing this will get you about a 3-6″ long rhizome root that will have multiple shoots pushing through the soil.
  4. Then, use the handheld trowel to gently lift up a clump of Blunt Mountain Mint.  Since you cut through the roots that lead back to the mother plant, it will be easy to pull up.
  5. Use pruning sheers to separate the shoots.  Or, just plant the entire clump in a new location where you would like to have the plant!
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A small clump of mountain mint I removed.
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Young shoots about 2 weeks after division. These are ready to transplant out to a final location.

Identification and Characteristics of Blunt Mountain Mint

This is a clump forming plant that spreads via rhizomes.  It grows 2-3′ tall with equal spread once firmly established.  You will notice a strong spearmint aroma on crushed leaves.

Stalk / Stem

It has a smooth stalk with branching, and is four-sided (square).  The stalk is light green.  The branching will terminate and flowers with opposite leaves.

Leaves

Leaves of Blunt Mountain Mint are opposite and green near the base and lower on the stalk.  Near the top of the stalk the leaves are almost white and take on a more exotic appearance.  The leaves have a lance shape (lanceolate) and terminate at a point (acuminate).  Leaves grow about 2″ long by 1″ wide (at the widest point).

Flower

Hundreds of tiny tubular flowers form clusters.  Each tube has two lips.  In full sun many blooms will occur. A pair of silver/white bracts will be at each flower cluster.

Pycnanthemum muticum flower mountainmint

Root

This is a shallow-rooted plant.  The roots will spread out and send up new stalks, increasing the size of the plant over time.  Since it is shallow, it is not hard to control the size.

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A shallow rhizome root of Mountain Mint.

Is Blunt Mountain Mint invasive?

Blunt Mountain Mint is a clump forming plant and slowly spreads via rhizome roots. It is not invasive and is easily managed by removing the unwanted shoots each Spring.

The slow clump expansion means that it is easily managed. This is in stark contrast to other aggressive members of the mint family such as Bee Balm or Obedient Plant, which are quite aggressive and send out runners far and wide.

Wildlife, Pests, and Diseases associated with Blunt Mountain Mint

Pollinators

If you grow a mature specimen of Blunt Mountain Mint, you will be treated to an amazing display of pollinators. There are hundreds of them at a single time, and not just one but many different species. A recent academic field survey found over 75 different species of insect visited Blunt Mountain Mint over a two month period, far more than any other species in the study! [3]

Pests

Due to it’s strong aroma, you don’t see any pest damage on the plant. Everyone seems to like the flowers, but that is all. I never see any holes in leaves, etc.

Deer and Rabbits

Deer and rabbits will not eat Blunt Mountain Mint due to the strong aroma/flavor of the leaves. I have never seen damage to these plants.

Disease

Blunt Mountain Mint doesn’t seem to be effected by any major diseases. However, it can be cosmetically effected by Rust.

Where you can buy Blunt Mountain Mint

Mountain Mints are not typically sold in nurseries, as it isn’t a typical ‘garden friendly’ plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map.

Where to buy seeds

Seeds of Blunt Mountain Mint are not widely available. I’ve only located a couple of sources. One source I can readily endorse is Prairie Moon Nursery, as they generally have high quality product. Note – the seeds are not always in stock.

Uses of Blunt Mountain Mint

Garden Uses

Blunt Mountain Mint can be used in a variety of ways in the garden. It can be used in a formal flower bed, assuming you take care to prune it each Spring. It makes an excellent border garden plant. And it wilder areas such as a micro-prairie or meadow, it can compete with all but the tallest of species.

Companion Plants

For companion plants, you really can’t go wrong as long as it doesn’t get shaded out. The white flowers and silvery bracts on the plant give it a nice silver/white hue that really blends with just about any color.

For some companion plants that bloom concurrently:

For companion plants that bloom before Blunt Mountain Mint, try Virginia Bluebells, Penstemon digitalis, Prairie Phlox.

For companion plants that bloom after Blunt Mountain Mint, Aromatic Aster, Smooth Blue Aster, Spotted Bee Balm all would do well in similar conditions.

Medicinal Uses

I have found no documented medicinal uses for Blunt Mountain Mint. The leaves can be used to make a tea, and they truly have a minty aroma. So one could use it for some homemade potpourri.

Edible

Blunt Mountain Mint isn’t considered edible, but a tea can be made from the leaves. Simple gather leaves and steep them in hot water to brew a weak tea.

Find more native plants here

References:

[1] – Pycnanthemum muticm. United States Department of Agriculture. Accessed July 1 2022.

[2] – Vidrine, MALCOLM F., et al. “The Cajun prairie restoration project.” Proceedings of the Seventeenth North American Prairie Conference, North Iowa Area Community College, Mason City, USA. 2001.

[3] – Pant, Anita, and Susan Mopper. “Variation in Insect Richness on Six Prairie Plant Species.” Southeastern Naturalist 20.1 (2021): 212-226.

Joe Foster

Hi - I grew up outdoors in nature - hiking, fishing, hunting. In high school I got my first job at a garden center where I learned to garden and landscape. I've been growing plants from seed and designing native plant gardens for over six years. I hope to share some of my knowledge with you! Additionally I am a wood worker / DIY enthusiast. I enjoy designing/building projects (with hand tools when I can!). I hope to give you some tips and useful information!

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