Arenaria montana 'Mountain Sandwort'

Arenaria montana is a classic little alpine or rock garden plant, still relatively unknown to many gardeners.
The plant has narrow, glossy green leaves that form prostrate mats of foliage that are evergreen. In mid-spring, Sandwort is blanketed by relatively large 1.25cm (½in) wide, white flowers. It is an impressive show that has tremendous impact when grown en masse and is even more spectacular when spring-flowering bulbs are mixed in.

Mountain Sandwort does best in full sun to partial shade and prefers dry to average moisture levels with very well-drained soil. It is considered to be drought-tolerant, and thus makes an ideal choice for a low-water garden. It is not particular as to soil type or pH and is somewhat tolerant of urban pollution.
Plants will grow to be only 5cm (2in) tall at maturity extending to 1.5cm (4in) tall with the flowers, with a spread of 30cm (12in). Its foliage tends to remain low and dense right to the ground and grows at a slow rate. Under ideal conditions can be expected to live for approximately 5 years.

With a ground-hugging habit of growth this useful plant can be used at the front of the border, it can be used en masse as a lawn substitute for low foot traffic areas and is a good candidate for a green roof.
They are at their loveliest spilling over edges of walls and rocks to create the illusion of a living waterfall and will quickly fill in the spaces between stepping stones or trail down the sides of walls.

• Awarded the RHS Award of Garden Merit
  In 1993 Arenaria montana was awarded the Royal Horticultural Society’s Award of Garden Merit (AGM).
  A key indicator that this variety is worth growing in your garden.

Sowing: Sow in spring or in autumn.
Prepare pots or trays with good free draining seed compost; moisten by standing in water, then drain. Surface sow two seeds per pot or cell and press them gently down to firm them in. Cover the seed with a fine layer of vermiculite if you have it.
Seal pots in a polythene bag or cover trays with clear plastic lids until after germination. It is important to keep soil slightly moist but not wet.
Remove the polythene bag once the first seedlings appear. Germination usually take 14 to 30 days at temperatures around 12 to 18°C (55 to 65°F), occasionally germination may be erratic, if all seeds do not germinate in 4 weeks do not throw, remove pots/tray to a cool shaded area.
The seedlings are usually large enough to handle after 4 to 5 weeks. Transplant the seedlings into small 9cm (3½in) pots. If you require the plants to cover a large area, two or three seedlings can be planted in one pot. Place the pots in a coldframe or unheated greenhouse to grow on.
Before transplanting the plants outdoors, hardened the plants off gradually by placing them outside in a sheltered position during the day; bring them in at night to avoid frosts. They do best in moist but well draining soils but are not suited for heavy dry soils or damp soil amend soil if necessary before planting. Space plants 20cm (8in) apart.

Cultivation:
Arenaria montana has shallow root systems and seedlings can dry out very quickly. Cover substrate with vermiculite or mulch to retain water and keep your eye on small plants until they establish themselves
A relatively low maintenance perennial, simply remove damaged foliage in spring and fertilise with a complete balanced fertiliser, don't fertilise after mid September. It should only be pruned after flowering to avoid removing any of the current season's flowers.

Plant Uses:
Suitable for ground cover, rockeries, cascading over walls, borders, edging paths, green roofs or containers

Origin:
Arenaria montana is native to mountainous regions of southwestern Europe, from the Pyrenees of France to Portugal.

Nomenclature:
The genus name Arenaria is taken from the Latin arena meaning 'sand', referring to the sandy habitats of many species. The common name 'sandwort' also refers to this.
The species name montana means simply 'of the mountains', referring to its origin.
Arenaria montana is a member of the Caryophyllaceae family, a cousin of the popular Dianthus genus.