Silver Swan Euphorbia

Silver Swan Euphorbia (Euphorbia characias 'Silver Swan') is a neat evergreen mound of grey green leaves edged in creamy white, about 80cm tall and the same across. In late winter it lifts domed heads of lime green and cream well above the foliage, and it holds that display for months. It thrives on drought, poor soil and salt wind, and it holds a border together.

Why you'll love it

• Foliage that works all year. The white edged blue grey leaves give twelve months of structure, not a two week flowering moment.
• It prefers being left alone. Drought tolerant, salt tolerant, frost hardy and happy in poor soil, so it suits gardens that get watered rarely.
• An unusual flower colour. The lime green and cream heads sit beautifully against silver, burgundy or deep green planting.
• Predictable size. It settles at roughly 80cm by 80cm and stays there, so a border planted to a plan still reads as planned in three years.

Where it works best

Borders and edging. Plant 60cm apart for a continuous silver edge. At that spacing the mounds touch without crowding, which keeps air moving through them.

Mass planting and rockeries. A drift of five or seven reads far better than a single plant, and the sharp drainage of a rockery suits it exactly.

Coastal gardens and pots. Salt wind does not mark it. In a pot 400mm or wider it holds shape, provided the mix is gritty and drains freely.

Growing Silver Swan Euphorbia in Australia

Position and climate. Full sun keeps the variegation bright and the mound tight; in shade it stretches and pales. It suits warm temperate, cool temperate and Mediterranean gardens and is frost hardy. Humid summers invite stem rot.

Soil. Free draining above all, and poor is fine. On clay, plant on a raised mound with grit worked through, and mulch with gravel rather than bark.

Water and feed. Water weekly for the first season, then only through long dry spells. It needs no feeding in reasonable soil, and rich conditions produce soft floppy growth that opens up in the middle.

Pruning and sap. Cut each spent flowering stem to the base once the heads brown, which keeps the plant dense. Wear gloves and eye protection: the milky sap is a skin and eye irritant, and it is toxic if eaten.

What to expect when it arrives

Three sizes are grown: 140mm pots in packs of ten, 200mm in packs of six and 250mm in packs of three. The 140mm plants are the economical choice for a long border edge, ten covering about 6m at 60cm spacing. The 200mm and 250mm sizes give an established mound in the first season.

Plants travel well because the foliage is firm rather than soft. Expect a few still weeks, then new growth from the base, with flowers in the second spring. Delivered Australia wide, with delivery from $29.95 and a minimum order of $300 before delivery, and every plant carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• Browse the drought tolerant range.
• Planning a waterwise garden.
• See other variegated foliage plants.
• Compare rockery and gravel garden plants.

Common questions

Is it safe around pets and children?

No. All euphorbias carry a milky sap that irritates skin and eyes badly, and it is toxic to cats, dogs and people if swallowed. Wear gloves when pruning and place it away from areas where pets or small children play.

How many do I need for a border?

Plant 60cm apart, so roughly six plants for every 3.5m of edge. That spacing lets the mounds meet within two seasons while keeping air flowing between them.

Why has it thrown plain green shoots?

Variegated plants occasionally revert. Cut any all green stem out at the base as soon as you see it, because green growth is more vigorous and takes over.

How long does it live?

Expect four to six good years, which is normal for the species rather than a fault. Cutting spent flower stems to the base each year keeps it vigorous for longer.