Cushion spurge
Euphorbia polychroma ·
A perfect dome of fresh green covered in sulphur-yellow bracts in mid-spring, turning red in autumn. One of the neatest plants in the garden.
- Size
- 18 in tall, 24 in wide
- Zones
- 4 to 8
- Light
- Full sun to part sun
- Flowers
- Late April to late May
- Pets
- Toxic (mild)
- Job in a bed
- Drift
A bed built around cushion spurge
The planner designed this bed around cushion spurge when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 715 that suit those conditions and its dry soil, and says below why cushion spurge stands where it does.
The plants
- 1 Cushion spurge × 3, yellow
- 2 Coral bells 'Firefly' × 8, red
- 3 Heath aster 'Snow Flurry' × 7, white
- 4 Little bluestem 'Standing Ovation' × 3, tan
- 5 Stiff goldenrod × 3, yellow
- 6 Dwarf English boxwood × 1, dark green leaves
- 7 Star of Persia × 4, purple
- 8 Hyacinth 'Delft Blue' × 12, blue
Why this plant
- The only dense clusters. The others are airy sprays, daisies, plumes and others. Shape reads at a distance, where colours blur.
Why here
- At the back. At 18 in it is seen over heath aster 'Snow Flurry' (6 in) in front of it, and has nothing behind it to hide.
- A step in the back row. Next to little bluestem 'Standing Ovation' (3½ ft) and dwarf English boxwood (2½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for five weeks. From late April to late May.
- Fills a gap. For three of those weeks nothing else on the plan is in flower.
Planned as an English border: 5 of the 6 groups (83%) are drifts, longer along the bed than they are deep. Hot colours (yellow and red) with purple and blue as the cool notes, and white and tan to calm things between them. Dwarf English boxwood is grown for its leaves rather than its flowers.
The planner's own design check: 13 Excellent, 4 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where cushion spurge goes in a border
At 18 in it belongs at the front of a bed. In the planner's ten height classes it is short (12 to 18 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
The acid yellow is at its best with blue and purple: grape hyacinths, aubrieta, dark tulips. Its dome shape is as valuable as its colour, a full stop among looser plants.
- Bright spring colour with tulips
- A tidy dome at the front of a sunny bed
- Autumn foliage colour
What to plant with cushion spurge
Plants recorded as good partners for it, and what each pairing does:
- Tulip: purple against yellow, opposite each other on the colour wheel, if you choose those colours, in flower together for four weeks.
- Grape hyacinth: blue against yellow, opposite each other on the colour wheel, in flower together for three weeks; spires rising out of its mound; low enough (6 in) to stand in front of it.
- Catmint 'Walker's Low': in flower together for two weeks, from mid May; spires rising out of its mound; happy in the same dry soil.
Questions about cushion spurge
Does cushion spurge need sun or shade?
Cushion spurge grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).
It wants dry, sharply drained soil, of average fertility, and little watering once settled.
What zones does cushion spurge grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does cushion spurge flower in my zone?
In zone 5 it flowers late April to late May. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 4 | Early May to late May |
|---|---|
| Zone 5 | Late April to late May |
| Zone 6 | Mid April to mid May |
| Zone 7 | Mid April to early May |
| Zone 8 | Early April to early May |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should cushion spurge be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.
It grows 18 in (45 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many cushion spurge plants do I need?
At 18 in apart, set out in staggered rows:
- 5 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 17 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used three in one group.
Is cushion spurge poisonous to dogs and cats?
Yes: mild toxicity to people, dogs and cats. The sap can irritate skin and eyes. Can cause vomiting and diarrhoea if eaten.
Rated from NC State Extension. Where references disagree, the more cautious rating is used.
Is there a pet-safe plant like cushion spurge?
These come closest to doing what cushion spurge does, and no toxicity is recorded for them:
- Tickseed 'Early Sunrise': the same job in a bed, the same size and the same colour; flowers early June to late August.
- Blanket flower 'Mesa Yellow': the same job in a bed, the same size and the same colour; flowers mid June to early October.
- Sundrops: the same job in a bed, the same size and the same colour; flowers late May to mid July.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after cushion spurge?
Cushion spurge is over by late May. These start as it finishes and carry the same spot on, so it never goes flat:
- Catmint 'Walker's Low': from mid May to mid September, 24 in tall (a recorded partner).
- Lady's mantle: from late May to early July, 18 in tall.
- Creeping thyme: from early June to mid July, 3 in tall, to stand in front of it and cover its fading stems.
What does cushion spurge look like in winter?
Cushion spurge dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
More Euphorbia
- Cushion spurge 'Bonfire' Euphorbia polychroma 'Bonfire'
- Cypress spurge Euphorbia cyparissias
- Donkey-tail spurge Euphorbia myrsinites
- Flowering spurge Euphorbia corollata
- Griffith's spurge 'Fireglow' Euphorbia griffithii 'Fireglow'
- Mediterranean spurge Euphorbia characias subsp. wulfenii
- Purple wood spurge Euphorbia amygdaloides 'Purpurea'
- Spurge 'Ascot Rainbow' Euphorbia x martini 'Ascot Rainbow'
- Spurge 'Blackbird' Euphorbia 'Blackbird'
- Spurge 'Chameleon' Euphorbia dulcis 'Chameleon'
- Wood spurge Euphorbia amygdaloides var. robbiae
In these guides
Every fact on record
- Type
- Perennial
- Size
- 18 in (45 cm) tall, 24 in (60 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Short (12 to 18 in)
- Place in the bed
- Front
- Flowers
- Late April to late May; dense clusters; yellow
- Leaves
- Medium texture, herbaceous; green
- Shape
- Mounding, clumping
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun, part sun
- Soil
- Average, dry and sharply drained
- Water
- Low
- Feeding
- None needed
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.