North America Native Plant

Swartz’s Polytrichum Moss

Botanical name: Polytrichum swartzii

USDA symbol: POSW

Habit: nonvascular

Native status: Native to North America  

Synonyms: Polytrichum algidum I. Hagen & C.E.O. Jensen (POAL21)  ⚘  Polytrichum commune Hedw. var. swartzii (Hartm.) Nyholm (POCOS2)   

Swartz’s Polytrichum Moss: A Hardy Native Ground Cover for Cool Climates If you’ve ever wandered through a northern forest and noticed thick, cushiony carpets of green covering the forest floor, you might have encountered Swartz’s polytrichum moss (Polytrichum swartzii). This remarkable native moss brings a touch of the wild northern ...

Swartz’s Polytrichum Moss: A Hardy Native Ground Cover for Cool Climates

If you’ve ever wandered through a northern forest and noticed thick, cushiony carpets of green covering the forest floor, you might have encountered Swartz’s polytrichum moss (Polytrichum swartzii). This remarkable native moss brings a touch of the wild northern woods to your garden, offering year-round color and texture in spots where other plants struggle to thrive.

What Exactly Is Swartz’s Polytrichum Moss?

Swartz’s polytrichum moss is a bryophyte – a group that includes mosses, liverworts, and hornworts. Unlike flowering plants, this moss reproduces through spores rather than seeds and doesn’t have true roots, stems, or leaves in the traditional sense. Instead, it forms dense, cushion-like colonies that can create stunning ground cover in the right conditions.

This hardy little moss is also known by its scientific synonyms Polytrichum algidum and Polytrichum commune var. swartzii, reflecting its close relationship to other members of the polytrichum family.

Where Does It Call Home?

As a native North American species, Swartz’s polytrichum moss naturally occurs throughout arctic and subarctic regions, extending down into boreal forests. You’ll find it thriving in some of the continent’s most challenging climates, from Alaska down through Canada and into the northern United States.

Why Consider This Moss for Your Garden?

While you might not think of moss as a garden plant, Swartz’s polytrichum moss offers several compelling benefits:

  • Year-round interest: This evergreen moss provides consistent color throughout all seasons
  • Low maintenance: Once established, it requires minimal care
  • Erosion control: Its dense growth helps stabilize soil on slopes and problem areas
  • Unique texture: Creates interesting visual contrast with other plants
  • Problem-solver: Thrives in challenging spots where grass and other plants fail

Perfect Garden Spots

This moss shines in specific garden situations:

  • Shaded woodland gardens
  • Rock gardens with consistent moisture
  • Areas between stepping stones
  • North-facing slopes
  • Spots with poor drainage where other plants struggle

Growing Conditions and Care

Swartz’s polytrichum moss is remarkably hardy, thriving in USDA zones 1-6. It prefers:

  • Light: Partial to full shade
  • Moisture: Consistent dampness (but not waterlogged conditions)
  • Soil: Acidic conditions with good organic matter
  • Temperature: Cool, humid environments

The beauty of working with this moss lies in its self-sufficiency. Unlike traditional garden plants, it doesn’t need fertilizing, regular watering (once established), or pruning. Simply ensure it has adequate moisture and shade, and it will slowly spread to form those characteristic dense mats.

How to Identify Swartz’s Polytrichum Moss

Look for these distinctive features:

  • Dense, cushion-like growth pattern
  • Upright shoots that create a miniature forest appearance
  • Star-shaped arrangement when viewed from above
  • Rich green color that persists through winter
  • Attachment to rocks, logs, or other solid surfaces rather than just soil

The Bottom Line

While Swartz’s polytrichum moss might not be the showiest plant in your garden, it serves an important role as a reliable, native ground cover for challenging spots. If you have shaded areas with consistent moisture in zones 1-6, this hardy moss could be exactly what you need to create a naturalistic, low-maintenance garden feature that connects your landscape to the wild beauty of North America’s northern forests.

Remember, working with native mosses like this one helps support local ecosystems while solving common garden challenges – a true win-win for both gardener and environment.

Swartz’s Polytrichum Moss

Classification

Group

Moss

Kingdom

Plantae - Plants

Subkingdom
Superdivision
Division

Bryophyta - Mosses

Subdivision

Musci

Class

Bryopsida - True mosses

Subclass

Bryidae

Order

Polytrichales

Family

Polytrichaceae Schwägr.

Genus

Polytrichum Hedw. - polytrichum moss

Species

Polytrichum swartzii Hartm. - Swartz's polytrichum moss

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA