Grow and Care for Irish Moss Ground Cover

Grow Irish moss in sun to part shade and keep the mat barely moist. Irish moss is Sagina subulata, a one-to-two-inch flowering carpet between pavers — not the dried sea moss sold in a jar.

Give it sun to part shade, soil that drains, and only light foot traffic

Irish moss is Sagina subulata, a flowering pearlwort that only looks like moss. Give it open sun or light shade and ground that stays barely moist without sitting wet. [1] It stays about one to two inches tall and fills slowly to about a foot across, so it never needs mowing. [2] Walk on it the way you walk on a path, not as a backyard for running children. Gold Scotch moss is the same plant with chartreuse leaves, not a second care job. Tiny white stars sit on thin stalks from late spring, then come and go through summer.

Keep the mat barely moist — dry or soggy both turn it brown

Water so the soil stays barely moist, not bone-dry and not waterlogged. Irish moss is not a drought plant. A new planting needs that even moisture until the pieces knit. After that, water in a dry spell, and skip watering after a long rain. [3] Brown patches usually mean the water was wrong in either direction, or the joint baked in afternoon sun. Cut the brown out, then fix the moisture. In a hot summer the mat may brown and then green again as nights cool; that is not a cue to drown it. [4]

1. Water a new planting so the soil stays barely moist until the plants meet.
2. After the mat knits, water in a dry spell, then let the surface dry slightly before you water again.
3. If patches brown after a wet week, stop daily watering and let the ground drain.
4. Cut out brown patches with scissors or a knife, then correct the water so the green edge can fill the hole.

Divide a rooted piece in spring or fall

The usual home start from a plant you already own is a strip of the mat with roots still attached, not a leafless stem. Do that in spring or fall, and replant the same day. If you are filling a new path from nursery plugs or seed, see Planting Irish Moss.

1. Slice a healthy green patch so each piece has foliage and roots attached.
2. Replant the pieces the same day in soil that drains, and press them so the roots touch the ground.
3. Water until they take hold, and keep the new patches barely moist.
4. Stay off the new patches until they hold, so footsteps do not tear the roots loose.

Not sea moss — and not a true moss or Corsican mint

Dried Irish moss in a supplement jar is sea moss, Chondrus, a seaweed. This garden plant is Sagina, a flowering carpet you grow between pavers. True moss wants shade and stays wet; this plant wants sun to part shade and soil that drains. Corsican mint is Mentha, a tiny mint that smells like mint when you step on it — see How to Grow Mint. Shops also sell sandwort as Scotch moss; that plant is Arenaria, not this gold Sagina — see How to Grow Sandwort. Creeping thyme is a tougher walkable mat with a kitchen smell — see How to Grow Creeping Thyme.

If patches brown, stop guessing and check the water. Dry joints and soggy joints both burn the mat. Keep it in sun or light shade, and walk on it only as a path.