Arenaria Plant Growing & Care Guide for Gardeners

In this Gardener's HQ guide, we'll explore cultivating Arenaria plants in your garden, indoor spaces, and other settings.

Irish Moss, Scotch Moss, and Sandwort: Cultivation & Garden Use

The common names for the Hardy perennial Arenaria include Irish Moss, Scotch Moss and Sandwort.

The plant that does not fair well in humid conditions.

It typically flowers from the late spring until the early summer months.

Arenaria franklinii by Matt Lavin.

Description of Irish moss (Arenaria)

Arenaria are low growing plants that reach a height of 30 cm at the most. Their leaves make an evergreen cushion that has multitudes of pink or white flowers when in bloom in the late spring. Due to their small size they make ideal plants for rockeries and to fill the gaps in between paving stones and in dry stone walling.

Wood Sandwort
Wood Sandwort by gmayfield10.

How to Grow Arenaria

If sowing seeds directly outside it is best to sow Arenaria species such as Irish Moss and Sandwort seeds on the surface in the early spring, when there is still a possibility of a late spring frost; alternatively the seeds can be sowed out in the Autumn.

However, as seeds are sown on the surface, they may be subject to predation from hungry birds through the winter.

If you prefer to grow Arenaria seedlings indoors first then they should be sown about seven weeks before you plan to put them outside (after the last frost of spring).

Germination typically takes from a week to a month and should be performed at a temperature of around 13 to 18 Celsius.

The seedlings should be planted in full sunlight, they will however still thrive in partial shade in very hot summers.

They prefer a soil that is well drained, with a pH of between 6 and 8 and sandy or gritty in nature.

Caring for Arenaria

Arenaria is easy to look after, though it may require regular watering in the heart of a very hot summer. It may also be necessary to give them a light feeding if required.

The best way of propagating the plants is by seed, though cuttings may be taken in the Summer.

Arenaria Growing and Care Guide

Common Names: Sandwort, Wood Sandwort, Fendler's Sandwort, Also Sandwort: English, Marsh, Blunt-leaved, Large Leaved, Mountain, Ballhead, Bear Valley); Scotch moss; Irish Moss
Family: Caryophyllaceae (Pinks and Carnations).
Life Cycle: Hardy Perennial.
Height: 5 to 11 inches (12 to 28 cm).
Growing Region: Zones 3 to 8 (species dependent).
Flowers: Late Spring through to Early Summer.
Flower Details: Pink or White.
Foliage: Evergreen.
Sow Outdoors: Surface. Early Spring before last frost, or late Autumn. Spacing 3 to 4 inches (7 to 10 cm).
Sow Indoors: Use Peat pots . Germination time 1 week to 5 weeks. Temperature 55 to 65°F (13 to 18 °C), 7 or 8 weeks before expected last frost. Transplant outdoors following the last frost.
Requires: Full Sunlight (Partial shade in very hot areas), Good drainage, Soil pH 6 to 8, Gritty, Sandy soils. Regular watering, Light feed, best grown from seed but can be propagated by division at the start of spring or by taking cuttings in the summer.

Common Questions

How many members does the Arenaria genus have?

The Arenaria genus, also known as sandwort, includes about 90 species of flowering plants.

Do members of Arenaria make a good garden or landscaping plant?

Yes, Arenaria species are often used in rock gardens and as groundcovers due to their low-growing habit and bright white flowers.

Which Arenaria species are most frequently grown by gardeners?

The most frequently grown species is Arenaria montana, commonly known as mountain sandwort, which produces white star-shaped flowers.

Are members of the Arenaria plant genus fragrant?

Arenaria species are generally not known for their fragrance.

What is the perfect location to grow Arenaria?

Arenaria prefers full sun to partial shade and well-drained, sandy soil. It's especially suited to rock gardens and between stepping stones.

Is Arenaria invasive in the USA, if so in which states?

Arenaria is not typically considered invasive in the USA, though some species can spread readily in the right conditions.

How do I remove Arenaria plants from my garden?

To remove Arenaria, pull out the plants, making sure to remove as much of the root system as possible to prevent regrowth.


The Arenaria genus, commonly known as sandwort, is part of the Caryophyllaceae family and comprises around 100 species of annuals and perennials. Native to the temperate regions of the Northern Hemisphere, these plants are typically low-growing and spreading, making them ideal for rock gardens and as a ground cover. Many species produce small, white, star-like flowers.

Sandworts are hardy plants that prefer full sun to partial shade and well-drained soil. They can tolerate a wide range of soil conditions, including poor and rocky soils. Given their native habitat in mountainous regions, many species are tolerant of cold and drought conditions once established.

I hope that you enjoyed this guide on Arenaria. You may also enjoy the following Gardener's HQ growing guides: How to grow Carnations and Sagina plants.