Sand sedge

How to recognise it

Habit

Low sedge of 10–40 cm, with shoots arising in a row along a long, creeping rhizome.

Leaf

Narrow, 2–4 mm, stiff, often slightly inrolled and curved, grey-green to dark green, about as long as the stem.

Flower

Dense, egg-shaped, pale brown head of 2–8 cm with 5–15 spikelets: the upper ones male, the middle ones mixed and the lower ones female; two stigmas; in May–June.

Stem

Three-angled, often slightly curved, rough below the flower head, without nodes.

Roots

Long, tough, brown rhizome that runs for metres in a straight line through the sand, with a shoot every few centimetres.

Confusion with

Brown sedge looks similar, but grows on wet ground, and its middle spikelets are male. Marram is a tall grass with inrolled leaves and a long, cylindrical flower spike.

Flowering: May–June

Why grow it?

• Binds loose sand with a network of long rhizomes and so helps stabilise dunes and drift sand.
• A true survivor: it copes with drought, blazing sun, wind, salt spray and poor soil.
• Between its sparse shoots, open sand remains where mining bees, digger wasps and tiger beetles hunt and dig their nests.
• Typical of the coastal dunes and the Campine heaths: a piece of dune landscape in your garden.
• Its rhizome was once traded as a substitute for an expensive exotic herb, sarsaparilla.

Sand sedge: where does it grow best?

• In the wild: coastal dunes, drift sand, dry heath, sandy verges and open pine woods on sand.
• Full sun.
• Dry, loose, nutrient-poor sandy soil; both chalky dune sand and acid heath sand suit it.
• In the garden: in a sand or heather garden, on a sunny bank or as low cover between thyme and sheep’s-bit. On rich, moist soil it is crowded out.

Goes well with

• Sheep’s-bit: Blue pompons in summer for bees, on the same poor sand.
• Wild thyme: Fragrant purple cushions between the rows of shoots.
• Grey hair-grass: Blue-grey tufts that bind drift sand together with sand sedge.
• Heather: Purple flowers in August–September in a heather garden.
• Biting stonecrop: Yellow stars in June on the bare sand in between.

Sand sedge: when and how to plant it?

1. Buy plants from a nursery for native plants; never dig up plants in the dunes or on heathland, as these habitats are fragile.
2. Plant in March–April or September–October in loose, poor sand, 30–50 cm apart; the rhizomes fill the space by themselves.
3. Do not add compost or potting soil to the planting hole: sand sedge likes poor soil.
4. To stabilise a bank quickly, plant more densely: 4–6 plants per m².
5. Water during long dry spells in the first season, until the plants have rooted.
6. Sowing also works: scatter seed on bare sand in autumn and press it in; it is slow, though.

Care

Watering

Never needed after the first year.

Feeding

Never: fertiliser only helps the grasses and weeds that crowd it out.

Weeding

In the first years, pull out grasses and weeds between the shoots.

Spreading

In loose sand it can run a long way. In spring, cut off runners with a spade or install a root barrier.

Tidying

Rake away dead leaves in March if you like; it is not necessary.

Tip: Plant sand sedge on a sunny sandy bank that keeps slumping: within a few years its network of rhizomes holds the sand, and you never need to mow.

Pruning and mowing

When: Not needed; dead leaves can be removed in March.

How:

• Leave the shoots standing all winter: the dry spikes are decorative and offer shelter.
• Rake or cut away withered leaves in March if it looks untidy.
• Never mow or cut it short in summer: that weakens the plant on dry sand.

Pruning calendar and basic rules

Propagation

Runners

In March–April or September cut off a piece of rhizome with a few shoots and replant it elsewhere in sand.

Seed

Ripens in July; sow on bare sand in autumn. Seedlings grow slowly.

Sand sedge: how does it get through the winter?

Hardy to −30 °C.

• The leaves stay partly green; the rest turns brown.
• Fully hardy, to about −30 °C; also withstands wind and salt spray.
• Small insects and spiders overwinter among the dry shoots.

Diseases and pests

• Invading borders: In loose, sandy borders it creeps between other plants. Install a root barrier or cut off runners.
• Crowded out: On richer soil, grasses crowd it out. Keep the soil poor and remove leaves and cuttings.
• Fading: In shade or on wet soil it dwindles. Move it to a sunny, dry spot.

Through the year

• March: Plant or move runners. Remove dead leaves.
• April: New shoots appear in rows.
• May: Flowering: dense, pale brown spikes.
• June: Flowering and seed set.
• July: Seed ripens; the spikes turn dark brown.
• September: Plant or cut off runners.
• October: Sow on bare sand.
• December: Dormant; the leaves stay partly green.

Did you know?

• Arenaria comes from the Latin arena, ‘sand’.
• Because the shoots emerge from the sand in straight lines, in the dunes you can see exactly where a rhizome runs underground.
• The rhizome was once traded as ‘German sarsaparilla’, a cheap substitute for the root of a tropical climber.