Sea spurge

How to recognise it

Growth habit

Perennial with a woody base and several stiff, upright, hairless stems of 20–60 cm, together forming a loose clump.

Leaf

Small, 0.5–2 cm, thick and leathery, grey- to blue-green, stalkless, closely packed and overlapping like tiles along the whole stem.

Flower

Yellow-green umbels with 3–6 rays and broad, rounded bracts; the tiny flowers sit in little cups with small glands. Flowers from June to October.

Fruit/Seed

A three-lobed capsule of about 4 mm with smooth, grey seeds. The seeds can float and so travel with the sea.

Roots

A long, deep root that reaches far into the sand and anchors the plant in blowing sand.

Confusion with

Cypress spurge has narrow, needle-like leaves and grows mainly inland on dry, chalky soil. No other spurge on our coast has such thick, tightly overlapping leaves.

Flowering: June–October · Pruning: March

Why grow it?

• A rare, true coastal plant that shows how plants adapt to salt, wind and blowing sand.
• Together with marram grass and sand couch, it helps to fix young dunes with its long roots.
• The small yellow-green umbels from June to October provide nectar late in the season for flies, beetles and ants.
• A sculptural plant with thick, grey-green leaves, attractive in a seaside or gravel garden on pure sand.
• Evergreen: a blue-green accent in the dunes even out of season.

Sea spurge: where does it grow best?

• In the wild: young dunes, the foredune and open patches in the white dunes, just above the strandline, among marram grass and sand couch.
• Full sun, in an open, windy spot.
• Pure, limy sand that dries out quickly. It tolerates salt spray and being buried by sand, but not wet or rich soil.
• In the garden: only suitable for a sunny seaside or gravel garden on pure sand, ideally close to the sea.

Goes well with

• Sea holly: A silvery-blue coastal plant for the same dry, sunny sand.
• Sea-kale: Large, blue-grey leaves and clouds of white flowers; also a plant of beaches and young dunes.
• Thrift: Pink cushions of flowers in spring, for the edge of a seaside garden.
• Burnet rose: A low, prickly rose with white flowers and black hips, for the back of a seaside garden.

Sea spurge: when and how to plant it?

1. Only buy it from a specialist nursery. Never pick, dig up or collect plants or seed in the dunes: the species is rare here and the dunes are largely protected nature reserves.
2. Plant in April–May in pure sand or a mix of sand and gravel, in full sun.
3. Set the plant slightly deeper than it was in the pot; it tolerates sand piling up around the stems.
4. Give each plant 40–50 cm of space.
5. Water now and then for the first few weeks until it has rooted, and then no more.
6. Wear gloves when planting: the milky sap irritates the skin.

Care

Water

Only for the first few weeks after planting. After that it manages with its deep root.

Feeding

Never: fertiliser makes it floppy and prone to rot.

Soil

Keep the soil poor and sandy; no compost or bark around the base. A thin layer of shells or gravel is fine.

Seedlings

On pure sand it sometimes self-seeds. Move seedlings while young or pull them up with gloves on.

Position

Do not put it next to a play area or sandpit, where children could break the stems.

Tip: Only plant sea spurge if you have a sunny garden on pure sand, ideally on the coast; otherwise it is better admired in the dunes, from the path.

Pruning and mowing

Pruning months: March.

When: In March, if needed.

How:

• In March, cut old, withered or toppled stems off at the base; new shoots come from the woody base.
• Leave healthy, evergreen stems standing: they will flower later in the year.
• Cut off spent umbels if you do not want seedlings.
• Rinse your secateurs afterwards: the sap is sticky and irritating.

Caution: The sap can spurt: wear gloves and protect your eyes.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In autumn, sow fresh seed from cultivated plants in a pot of pure sand and leave the pot outdoors; germination is often slow and erratic.

Cuttings

In spring, take a young shoot of 8–10 cm, wearing gloves. Dip the cut end briefly in lukewarm water until the sap stops flowing, let it dry and insert the cutting in damp sand.

Sea spurge: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Evergreen: the stems with their grey-green leaves stay standing in winter.
• Hardy to about −15 °C on dry, sandy soil; cold, wet soil is more dangerous than frost.
• In the dunes it is often partly buried by blowing sand in winter; in spring the shoots simply grow through it.

Diseases and pests

• Root rot: On wet, heavy or rich soil it rots. Only plant it in pure sand.
• Milky sap: Irritating to skin and eyes. Wear gloves and rinse immediately with plenty of water if it splashes.
• Too little sun: In shade it becomes floppy and topples over. Give it the sunniest spot you have.
• Trampling: In the dunes it suffers from trampling. Stay on the paths, with your dog too.

Through the year

• March: Cut old, withered stems off at the base.
• April: Plant in pure sand. Take cuttings.
• May: New shoots grow. Water newly planted specimens.
• June: The first yellow-green umbels.
• July: Flowers: flies and beetles on the small umbels.
• August: Full bloom in the dunes.
• September: Flowers and seed. Cut off spent umbels if you do not want seedlings.
• October: Last flowers. Sow in a pot of sand.
• December: Evergreen. Leave the seed pot outdoors.

Did you know?

• Paralias comes from the Greek paralios, ‘by the sea’.
• The seeds float in seawater and can travel with the currents to other coasts.
• In Australia, where it was introduced by people, sea spurge is an invasive plant that overruns beaches and dunes.