perennialN. America Native

Hoary Mountainmint

The Story

Plant Bio

Pycnanthemum incanum, the hoary mountainmint, is an erect, multi-branched herbaceous perennial native to eastern North America, forming spreading colonies via creeping underground rhizomes. The square stems bear opposite, broad-ovate leaves with toothed margins, emitting a strong spearmint aroma when crushed.

The upper leaves and floral bracts are covered in a fine, silver-gray down that gives the plant a frosted appearance in mid-summer. Small, white to pale lavender flowers with purple-spotted lower lips cluster in dense, flat-topped terminal heads that attract an exceptional diversity of native pollinators.

Uses & Benefits:

The frosted, silver-gray bracts provide a striking cool-toned visual contrast in the summer garden.

The highly aromatic foliage acts as a natural deterrent against deer and rabbits, making it useful for perimeter plantings.

Serves as an elite nectar source for diverse native bees, honeybees, and beneficial predatory wasps, and acts as a larval host for the wavy-lined emerald moth.

Essentials

At a Glance

Plant Type

Perennial

Height

48"

Width

48"

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7, 8

Water

Dry to medium

Humidity

Adapts well to regional summer humidity

Lifespan

Perennial

Native To

Eastern North America

Toxicity

Non-toxic

Bloom period

Summer – Fall

In flower about 6 months of the year

Planting

How to Grow

Select a site in full sun to partial shade with dry to medium, well-drained soil.
Plant container-grown specimens or bare-root divisions in early spring, spacing them at least three feet apart to allow for rhizomatous spread.
Water regularly after planting to establish the root system, then reduce watering as the plant develops high drought tolerance.
Avoid applying supplemental fertilizer, as rich soils cause the stems to become floppy and stimulate overly aggressive spreading.

Pro Tip

To control the aggressive underground spread of the rhizomes without chemical barriers, slice vertically into the soil with a sharp spade around the perimeter of the clump each spring.

Keep It Thriving

Care Guide

Do

Cut dead stems back to the ground in late winter or early spring before new growth emerges.
Ensure the planting site has excellent drainage to prevent root rot.
Provide light afternoon shade in hot southern climates to prevent leaf scorch.

Don't

Do not plant in consistently wet or waterlogged soils.
Do not fertilize, which leads to weak, floppy growth and excessive spreading.
Do not plant immediately adjacent to butterfly-rearing beds, as the flowers attract predatory wasps.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Divide
Propagate
Prune
Spring Cleanup

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Pollinator GardensNaturalized AreasErosion ControlMeadowsHerbaceous Borders

Companion Plants

Echinacea purpurea Symphyotrichum novae-angliae Monarda fistulosa Asclepias tuberosa

Multiply

Propagation Methods

Good to Know

Common Questions

Hoary Mountainmint questions

What zones can Hoary Mountainmint grow in?

Hoary Mountainmint is hardy in USDA Zones 4–8. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Hoary Mountainmint deer resistant?

Yes — Hoary Mountainmint is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

When does Hoary Mountainmint bloom?

Hoary Mountainmint typically blooms in summer through fall. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Hoary Mountainmint need full sun?

Hoary Mountainmint does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Is Hoary Mountainmint drought tolerant?

Yes — once established (usually after the first full season), Hoary Mountainmint handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.