The small, easy to care for and vigorous Irish-moss can be used in many ways in the garden as ground cover, rockery plant or lawn substitute.
Profile of Irish-moss:
Scientific name: Sagina subulata
Plant family: pink family (Caryophyllaceae)
Other names: heath pearlwort, awl-leaf pearlwort, awlleaf pearlwort, awl-leaved pearlwort , Scottish moss
Sowing time: March and April indoors; from Mid-May in bed
Planting time: autumn
Flowering period: June to August
Location: sunny to shady
Soil quality: sandy to loamy, moderately nutritious, humus rich
These information are for temperate climate!
Use in: ground cover, roof greening, grave planting, group planting, planters, dry stone walls, underplanting, area greening, roof garden, formal garden, patio, rock garden, potted garden, forest garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 4 (-32 °C / -25 °F)
Bee and insect friendly: a little
Plant characteristics and classification of Irish-moss
Plant order, origin and occurrence of Irish-moss
The Irish-moss (Sagina subulata) is not moss in the true sense of the word. Rather, it belongs to the pearlworts (Sagina) within the pink family (Caryophyllaceae). The small perennial is native to the whole of Central Europe. In English-speaking countries, Sagina subulata is known as “Irish moss” or “Scottish moss”.
Characteristics of Irish-moss
Like all pearlworts, Irish-moss also grows herbaceous with low or slightly upright stems. Its has a dense, cushion-like growth and star-shaped white flowers. The plant can quickly form a firm carpet or lawn by self-rooting side shoots. With a maximum growth height of 5 centimeters, the polster stays close to the ground.
Irish-moss bears about 6 millimeters long, pointed, light green leaves, which are arranged in opposite directions and have grown together at their base.
From about June to August small, white, cupped to star-shaped flowers cover the light green foliage. They sit singly or in a few together on short stems and show themselves in large numbers even in the shade.
Irish-moss – cultivation and care
As the “moss” in its name indicates, Irish-moss tolerates shadows well. A partially shady to shady location is therefore optimal for the small plant. If it is planted in a very sunny location, it can dry out quickly.
Sagina subulata prefers moist, but well-drained mineral garden soil. In case of waterlogging the roots start to rot easily, therefore loamy soil must be improved with sand before planting.
The best time for planting is in autumn. Since Irish-moss spreads quickly if left undisturbed, but is not particularly competitive, the soil should be carefully cleared of weeds before planting to make it easier for the young plants to grow. A plant will grow about 20 centimeters (8 in) wide, which results in a planting distance of 15 to 25 centimeters (6 to 10 in). It is best to always plant Sagina subulata in groups to create a dense cover. If Irish-moss is planted as a substitute for lawn, expect a demand of about 15 young plants per square meter (10 sq ft). After replanting, the soil must be kept evenly moist until the young plants have taken root well. Because of its strong urge to spread, the planting of Irish-moss is only recommended with appropriate limitation.
Irish-moss is not a friend of desert-like dryness. Therefore, water the plant regularly in the bed and tub when the natural rainfall is not sufficient. Since moisture evaporates through the evergreen foliage even during winter, water your plants on mild days when there is black frost.
In terms of nutrient supply the undemanding frugality of Irish-moss becomes obvious. If the plant thrives in the bed, rock garden, roof garden or on the grave, no fertilization is necessary. Only in the limited substrate volume of the tub or planter the nutrient supply is used up within 4-6 weeks after planting. In the period from April to August the monthly administration of liquid fertilizer is recommended. Then stop giving fertilizer so that the plant can prepare itself for the coming winter.
Irish-moss does not require a pruning for preservation. Only for optical reasons it may be desirable to cut the plant into shape. For example, if the groundcover grows into the garden path or presses against neighboring perennials in the planter, pruning is possible at any time. The same applies if the shoots become etiolate due to lack of light. If the green carpet is more like a tuft of hair that has fallen out of shape, use garden scissors to cut off anything that interferes.
The easiest way to propagate is by division. To do this, dig out the plant in spring or autumn, divide the root ball into two or more segments and place these in the soil at the new location. If a larger number of plants are desired, seeds can be sown. This is the right way to do it:
- The best times for sowing behind glass are March and April
- Fill a seed bowl with soil for sowing, in order to spread the seeds
- Thinly sieve with sand or vermiculite, press on and moisten with fine spray
- Put on a transparent plastic hood and place it on a partially shady, warm window seat
If the tiny cotyledons break their way through the seed tray, the plastic hood has done its job. Keep the substrate slightly moist. The seedlings are pricked out when they have at least 2 pairs of leaves. By July/August, vital young plants have developed, which are then planted out in the bed.
From May onwards, it is also possible to sow outdoors. Mix the seeds with fine sand, especially when sowing large areas, so that they can be better scattered.
Diseases and pests
Sagina subulata is extremely robust and rarely shows signs of damage from disease. However, young plants often suffer from snail feeding. Keep the hungry animals away with snail fences or slug pellets. Otherwise, stunted growth and damage to the plant will mainly occur when it is too hot and dry or when there is waterlogging.
Irish-moss is frost-resistant to -32 °C / -25 °F, so you do not need to worry about measures for wintering in the bed. It is important to note that in autumn the fallen leaves are consistently removed so that no rot forms underneath. Only for a plant in a pot or box, some simple precautions should be taken to prevent the root ball from freezing to death. Before the first frost, place the pot on wood and cover with jute, fleece or foil.
Use in the garden
The fresh green, hardy Irish-moss can be used in the garden in many ways. On the one hand it is popular as a rock garden plant, for example in combination with mouse-ear chickweed (Cerastium), Breckland thyme (Thymus serpyllum) or wall bellflower (Campanula portenschlagiana), but also for greening dry stone walls, if the sunlight here is not too strong. And especially as a gap filler between treadplates and even as a roof greening or lawn replacement, the hardwearing Irish-moss can be used in the garden. Especially on shady areas, where the lawn grows only moderately dense, or on slopes that are difficult to maintain, Sagina subulata can be seeded or planted instead of grass, as long as the area is not subject to excessive use. Irish-moss remains naturally low and does not need to be mowed. Due to its dense padding, Irish-moss is also often used as an underplanting for trays and flower boxes and as a grave planting.
In addition to the classic Irish-moss (Sagina subulata), the variety ‘Aurea’ is also very popular. Its leaves shine in a beautiful yellow tone. The varieties ‘Green’ and ‘Lime Moss’ have bright yellow-green leaves.