Plant of the Week: Hoary mountain mint

While hoary mountain mint is certainly not the showiest plant in bloom on the High Line this week, it should by no means be overlooked. This native perennial herb is an absolute favorite of pollinators, and with pollinator numbers in serious decline everyone should have some in their garden, in my opinion.

Photo by Ayinde Listhrop.

The tiny white flowers with slight purple dots of hoary mountain mint are hermaphrodite and pollinated by insects. The leaves, when they emerge in spring, are deep green, and as the season rolls on the leaves mature to slightly paler towards the top, often described as if dusted by powder. The genus name Pycnanthemum means densely flowered and it is this dense flowering that leads to so many beneficial insects visiting the plant. It is quiet common to see butterflies, native bees, wasps, skippers as well as moths all feeding at the same time and long into the evening.

Photo by Ayinde Listhrop.

There are over 20 species of mountain mint native to North America and in my experience they can be hard to tell apart. Pycnathemum incanum, from my observations on the High Line, has a leaf shape that is narrower and longer than Pycnathemum muticum, whose leaves are wider and shorter. P. incanum is also more hairy than muticum, and less pungent. While Pycnathemun incanum may be consumed by humans, Pycnathemum muticum contains pulegone, a naturally occurring organic compound which if consumed can be toxic to the liver. However, Pycnathemum muticum is said to help fight pests such as chiggers and ticks if crushed and then rubbed to clothes. When crushed the leaves and flowers emit a very pleasing aromatic minty smell, the leaves also can be used to make a tea. Native Americans would crush the plant and inhale the vapors before entering sweat lodges.

Pycnathemum incanum can be found in woodland edges, dry open woods, thickets and hillsides from as far north as Canada down south to Florida and west to Illinois. Not only is it great for attracting beneficial insects, it is also deer resistant. It spreads and colonizes by rhizome roots, however they are shallow and easily divided if spreading gets too much. It is a great plant for grouping or mass plantings as well as perennial borders, and pairs well on The High Line with Knautia macedonica 'Mars Midget' and Andropogon geradii.

PLANTING TIP

This is a relatively low maintenance plant and tolerant of a range of soil, moisture and light conditions, but it prefers full sun and slightly more acidic soils. I have it growing in an area that gets more morning shade but good afternoon sun and it is doing well but slightly leggier and more prone to flop than plants grown in full sun. I have had some issues with the plant in early spring in more wind exposed areas where it did scorch, however a simple pruning and it came back quiet vigorously.

WHERE TO FIND THIS PLANT

Pycnathemum incanum can be found on the High Line amongst much showier flowering perennials in the Chelsea Grasslands, between West 18th and West 20th Streets, as well as the Wildflower Field & Radial Plantings between West 28th and West 30th Streets- just follow the pollinators.

The High Line's planting design is inspired by the self-seeded landscape that grew up between rail tracks after the trains stopped running in the 1980s. Today, the High Line includes more than 500 species of perennials, grasses, shrubs, and trees – each chosen for their hardiness, adaptability, diversity, and seasonal variation in color and texture. Some of the species that originally grew on the High Line's rail bed are reflected in the park landscape today. Every week we share one of our gardeners' current favorites with you.

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