Irish moss (Sagina subulata) is the perfect plant for damp, shady places where nothing else seems to grow. Irish moss works well as a ground cover or tucked into tight spaces between paving stones or in a rock garden where it will remain green and lush all year round. Once established, Irish moss will spread and fill in empty spaces with very little attention. To propagate Irish moss, divide the plant in early spring so the moss will have time to become established before winter.
Prepare the soil for the Irish moss ahead of time. Remove all weeds from the area and spade the soil to a depth of 6 inches. Spread 1 to 2 inches of compost or manure on the soil and work it in thoroughly. Rake the soil smooth.
Dig a clump of Irish moss with a trowel or a shovel. Use your hands to pull the clump apart into smaller sections. Alternatively, you can divide the clump with a shovel or a sharp knife. Be sure each clump has at least two or three roots.
Dampen the underside of the Irish moss section with a spray bottle and place the moss on top of the soil in the prepared location. Step on the moss to make contact with the soil.
Water the Irish moss immediately after planting and keep the moss damp for the first 1 to 2 weeks. After that time, water only during extended hot, dry periods.