Irish Moss, (Sagina subulata), is the perfect solution for those unsightly, empty gaps between paving stones. Very quickly, Irish Moss will form a dense, walkable, green carpet that will soften the harsh edges of the stones, while providing a lush, established feel to a walkway or patio. Irish moss is not difficult to grow, but it won't tolerate excessive heat or drought. Irish Moss requires a few hours of sunlight each day, but it does not tolerate hot afternoon sun well.
Ask friends and neighbors if they are willing to share a few small pieces of established Irish Moss. If you have Irish Moss established in other areas, tear off a few small "plugs". You can also purchase Irish Moss at a garden center.
Use a trowel or the corner of a hoe to gently loosen the top of the soil between the paving stones. Loosening the top of the soil will enable the roots of the Irish Moss to grip the soil.
Sprinkle a small amount of timed released granular fertilizer over the soil. Apply the fertilizer according to the label directions. Water the area well before you plant the Irish Moss. Reapply fertilizer to the Irish Moss every spring.
Tear the Irish moss into small pieces, and set the pieces where you want to establish the moss between the paving stones. Step on the Irish Moss to ensure that the roots make good contact with the soil. If you are planting a larger area, put a piece of plywood over the Irish Moss, and walk on the plywood until the Irish Moss roots are pressed firmly into the surface of the soil. This Irish Moss may appear a bit flat, but it will bounce back quickly.
Keep Irish Moss moist during the first growing season. After that, Irish Moss will only need to be watered during dry periods.