Sagina subulata, the moss-like ground cover that flowers before summer

Not always easy to grow a lawn in the dark shade of a building or tree. Moss often finds its way among the grasses, but somehow doesn’t get that elf-like green hue it would get in forests. Sagina subulata is a ground cover plant that doesn’t need much light and still manages to provide a true moss-like carpet that’s very pleasing to see. Even more so when it’s studded with white flowers at the end of spring!

Sagina subulata key facts:

Botanical name : Sagina subulata
Common name : heath pearlwort, Irish moss
Family : Caryophyllaceae

Type : perennial
Bearing : dense carpet
Height : 2 inches (5 cm)

Planting density : 6 to a square yard/meter
Exposure : full sun or part shade
Soil : cool, well-draining soil
Flowering – between May and August

Heath pearlwort, Sagina subulata, belongs to the same family as carnation (Caryophyllaceae). It has nearly the same type of growth as rock carnations, dense mounds and clumps, but its leaves are much narrower. Its color is also very different, lush bright green and even golden for Sagina subulata ‘Aurea’. It spreads into a soft carpet that won’t exceed 2 inches high (5 cm).

Another common name for it, “Irish moss” describes the appearance and color of the plant when the blooming comes around. It is covered with thousands of tiny white 5-petaled flowers that exhale a refreshing, delicious scent during the warmer daytime hours. Blooming begins at the end of spring and flowers keep appearing during the entire summer.

Planting Sagina subulata

• Sagina subulata is sold either in large rolls, as slabs ready to position in your garden, or in individual nursery pots.
• Planting can either take place in spring or in fall, since the plant is very hardy. Whichever option you choose, if you want to quickly cover a large surface, cut your clump into small one-inch squares (2-3 cm).
• Prepare the soil to loosen it up well, and spread organic fertilizer as an underlayer (dried blood, crushed horns…). Avoid mineral-based fertilizers because excess nitrogen would lead to growth that’s more leggy and less dense. If the soil tends to dry up in that area during the summer, also add a layer of organic matter like old decaying leaves or compost.
• Place each little plant square about 6 inches apart (15 cm), digging a small hole beforehand so they’re level with the ground around them. Water abundantly, then press down either with a roller or a simple plank that you walk on.

Caring for sagina subulata

• Sagina subulata grows as well in full sun as it does in part sun as long as the soil stays a bit cool in summer and weeds are removed.
• For larger areas, it’s recommended to run the roller along from time to time: this helps runners latch on the ground, these are little stems with roots and leaves that are sent out to colonize more space (like strawberry).
• Water with high-nitrogen liquid fertilizer to promote leaf growth, once a month from April to September.

Multiplying and propagation Irish moss:

To propagate your plant, the easiest is to separate the clump whenever you feel like it.

Another option is to make small cuttings from stems.

Diseases and pests:

• This plant fears dry soil: it quickly leads to yellowing, followed by leaves drying out. Remember to water frequently, and to add humus from any source (such as soil mix or compost) upon planting.
• However, note that heath pearlwort doesn’t like it when the ground is soggy. It helps to increase soil drainage with coarse sand or grit mixed into the topmost layer before planting, across the entire surface.

Landscaping and pairing

• This is one of the favorite plants for Japanese gardens , together with helxine. It flows around stepping stones on a walkway, or to decorate boulders and rocks jutting out from waterfalls. It can even serve as a full-blown lawn, but only if there isn’t too much foot traffic and that it stays cool over the summer. Both in full sun and part shade, the carpet grows with the same density.
• Use Sagina with other plants with abundant leaves to create a landscape full of greenery, with Hosta or ferns together for instance. Add in a few large rocks and let a small stream trickle through, it will look wonderful!
• Heath pearlwort will also beautifully dress the top of terra cotta pots, with either a Fuchsia or an outdoor bonsai emerging from the center.