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Common Haircap Moss

Polytrichum commune

Also listed as Pogonatum madagassum, Polytrichum alticaule

Also known as Common Haircap

groundcover⛅ part shade💧💧💧 high water❄ Hardy: Zone 2a – Zone 10b

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Common Haircap Moss is a non-vascular moss that forms dense, upright cushions or mats in damp, shaded areas. It thrives in acidic soils and moist conditions, making it ideal for woodland gardens, rock gardens, and areas where traditional plants struggle.

Why grow it

Common Haircap Moss establishes more reliably than many moss species in acidic, poorly drained soils where vascular plants often fail. Its dense, upright growth habit provides year-round ground coverage and soil stabilization with minimal maintenance once established, making it a practical choice for woodland restoration or shaded areas with compacted earth. Unlike some delicate moss species, Polytrichum commune tolerates moderate disturbance and variable moisture, though it grows more vigorously in consistently moist conditions.

Watch out for

Moss establishment requires patience; colonies may take one to two seasons to fill in visibly. Direct, intense sunlight or prolonged dry spells can cause dormancy or die-back, so site selection matters more than ongoing intervention. Avoid fertilizers and pH-raising amendments, which favor competing vascular plants and algae over moss growth.

Overview

Form
Upright
Growth Rate
slow
Size
0.25–1.5′ tall
Dormancy
evergreen
Family
Polytrichaceae
Erosion control

Native to the United States

Native Range

Widespread in temperate regions worldwide

Native to: New Jersey, New York

Seasonality

Season of Interest

SpringSummerFallWinter

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Companion Planting

Plants well with