Irish Moss
Sagina subulata
Not actually a moss but a charming perennial that forms dense, carpet-like mats of tiny bright green foliage. Perfect for filling gaps between stepping stones or creating a soft, cushioned groundcover in small spaces. In late spring, it's dotted with tiny white star-shaped flowers that add delicate beauty to this tough little plant.
Sun
Partial shade to full sun
Zones
4–8
USDA hardiness
Difficulty
Easy
Planting Timeline
Showing dates for Irish Moss in USDA Zone 7
All Zone 7 ground-cover →Zone Map
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Irish Moss · Zones 4–8
Growing Details
Zone-by-Zone Planting Calendar
Complete Growing Guide
Soil: Clay, Loam (Silt), Sand, Shallow Rocky. Soil pH: Acid (<6.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Growth rate: Medium. Maintenance: Medium. Propagation: Division, Seed. Regions: Coastal, Mountains, Piedmont.
Harvesting
The ovoid seed capsule is white and membranous with 4 blunt teeth along its upper rim. Each capsule contains several dark tiny seeds that can be blown about by the wind. The surface of each seed is minutely pebbly.
Color: White. Type: Capsule. Length: < 1 inch. Width: < 1 inch.
Harvest time: Summer
Bloom time: Spring, Summer
History & Origin
Origin: Chile to Argentina and the Falkland Islands
Advantages
- +Disease resistance: Foot Traffic
Companion Plants
Plant Together
Hostas
Both thrive in similar shade conditions and create layered woodland garden aesthetics
Ferns
Share preference for moist, shaded areas and complement each other's textures
Astilbe
Both prefer cool, moist conditions and Irish moss provides attractive groundcover beneath
Heuchera
Similar growing requirements and Irish moss softens the base of coral bells
Wild Ginger
Both are shade-loving groundcovers that naturalize well together in woodland settings
Ajuga
Both form dense mats and can create attractive mixed groundcover patterns
Moss Phlox
Creates beautiful contrast with Irish moss while sharing similar low-growing habit
Creeping Thyme
Both form dense, walkable mats and can be used together in stepping stone paths
Keep Apart
Black Walnut
Produces juglone which is toxic to many plants including sensitive groundcovers
Mint
Extremely aggressive spreader that will quickly overtake and smother Irish moss
English Ivy
Vigorous spreading vine that will climb over and kill Irish moss through competition
Pests & Disease Resistance
Resistance
Good disease resistance, may suffer in humid conditions
Common Pests
Aphids, spider mites (rare)
Diseases
Crown rot in poorly drained soils, fungal issues in high humidity