Irish moss (Sagina subulata) is a low-growing plant also known in Europe as heath pearlwort. Irish moss grows in dense mats on moist soil, and blooms in May and June with white five-petaled flowers that look like stars twinkling in a green field. Most commonly grown as an ornamental ground cover, Irish moss is also put to creative use in terrariums and to create living topiary sculptures.
The Colorado State University Extension recommends Irish moss as a ground cover for locations less than 50 square feet in area, in partial to full shade. Irish moss requires moist, rich soil, but makes an excellent bright green substitute for lawn in shady places where grass will not easily grow. The Colorado Extension suggests placing footpaths through a landscape area then planting ground covers such as Irish moss around the footpath stones, bricks or pavers as well as planting ground cover plants between perennials and shrubs to hold down weeds. However, Irish moss is tolerant of light foot traffic and can be planted in garden and woodland pathways without the use of pavers.
The University of Missouri Extension suggests terrariums--a glass container with a tight-fitting lid to hold in heat or moisture, although the term has more recently been used colloquially to refer to plants in any glass container--as an ideal way to grow plants indoors. The Missouri Extension recommends Irish moss for terrarium use with most organic soils, in medium, to low-light growing conditions. Irish moss thrives in the moist, warm conditions of a closed terrarium, and provides an excellent base to show off other taller terrarium plants.
Topiary is the art of sculpture with living plants. While traditional formal garden topiaries are composed of a dense shrub such as box which is trimmed into geometric or whimsical shapes, modern gardeners have been creating topiaries by forming a wire frame to the desired shape, filling it with damp peat moss, then planting it with fast-growing spreading plants such as Irish moss. Many creeping green plants can be used for wire-frame topiary, but Irish moss has the advantage of being fast-growing and tolerant of a diversity of light conditions. The starry field of white flowers on blooming Irish moss also makes a lovely topiary accent. Irish moss can be interplanted with other plants like creeping woolly thyme to create a diversity of textures.