Euphorbia polychroma (Cushion Spurge) — Clump-forming, upright or spreading sub-shrub

Overview

Euphorbia polychroma is a clump-forming, upright or spreading sub-shrub perennial in the genus Euphorbia, part of the Euphorbiaceae family, with evergreen, semi-evergreen or deciduous; narrow, often blue-grey or glaucous, sometimes red-tinted in autumn foliage. Euphorbia polychroma grows best in full sun to partial shade; the woodland species tolerate dry shade, and tolerates light to moderately fertile loam and sand or chalk soils and acid and neutral or alkaline pH. Its UK hardiness is rated H4-H7. It is native to Europe.

About

Euphorbia polychroma is a clump-forming perennial sub-shrub with narrow, often blue-grey leaves and a long flowering season from May to September. It forms upright or spreading tufts and may be evergreen, semi-evergreen or deciduous depending on winter severity. Plants suit positions in full sun to partial shade and prefer well-drained soil. Handle with care: the milky sap is an irritant to skin and eyes.

Wikipedia contributors, CC BY-SA 4.0 — Euphorbia epithymoides

About the genus

Euphorbia is a large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae.

Wikipedia contributors, "Euphorbia", CC BY-SA 4.0 — Euphorbia

In the garden

Euphorbia polychroma is a European perennial that grows as a compact, clump-forming sub-shrub with narrow, glaucous leaves that can take on red tones in autumn. Flowering runs from May to September. The species performs equally well in exposed or sheltered sites and adapts to a wide range of soil pH levels. Place Cushion Spurge in full sun to partial shade; woodland forms tolerate dry shade. It prefers light to moderately fertile loam, sand or chalk but will not tolerate winter waterlogging, so choose free-draining soil or a raised bed on heavy ground. Aspect is flexible and it suits both exposed and sheltered garden situations. In UK gardening terms it covers H4–H7, meaning plants will survive average to fully hardy conditions across most of the country. Use it where its foliage can be appreciated: gravel beds, mixed perennial borders and dry woodland edges are all appropriate spots. Wear gloves and eye protection when pruning or cutting back, because the plant’s sap is an irritant. Avoid siting where winter wet accumulates, as prolonged waterlogging is the most common cause of decline for Cushion Spurge.

Growing conditions

Best soil and position for Euphorbia

Sunlight: Full sun to partial shade; the woodland species tolerate dry shade
Soil type: Light to moderately fertile loam, sand or chalk
Soil pH: Acid, neutral or alkaline
Soil moisture: Well drained; most dislike winter wet
Aspect: Any
Exposure: Exposed or sheltered
UK hardiness: H4-H7

Plant details

Euphorbia polychroma size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright or spreading sub-shrub
Foliage: Evergreen, semi-evergreen or deciduous; narrow, often blue-grey or glaucous, sometimes red-tinted in autumn
Native to: Europe
Toxicity: Irritant sap

Care notes

Pruning and caring for Euphorbia polychroma

Cultivation: Easy and largely self-sufficient given drainage. The milky sap is a genuine irritant to skin and eyes, so wear gloves and eye protection when cutting back and never handle the plant in strong sun. Most flower on stems produced the previous year, which makes correct timing of the cut essential. The spreading species can be invasive in loose soil, so site them accordingly.
Pruning: On the shrubby evergreen kinds, cut flowered stems right to the base once the bracts fade in summer, leaving this season's new shoots to flower next year. Cut herbaceous species down in late autumn.
Propagation: Divide herbaceous kinds in spring. Take basal cuttings of shrubby species in spring and rinse the cut end to stop the latex sealing it. Many self-seed freely.
Pest resistance: Rarely troubled by pests; aphids occasionally gather on soft new growth.
Disease resistance: Generally healthy. Euphorbia rust causes orange spotting and distorted shoots on some species and affected growth should be removed.

Frequently asked questions

How do I grow Euphorbia polychroma?

Easy and largely self-sufficient given drainage. The milky sap is a genuine irritant to skin and eyes, so wear gloves and eye protection when cutting back and never handle the plant in strong sun. Most flower on stems produced the previous year, which makes correct timing of the cut essential. The spreading species can be invasive in loose soil, so site them accordingly.

Where is the best place to plant Euphorbia polychroma?

Euphorbia polychroma prefers full sun to partial shade; the woodland species tolerate dry shade. It suits exposed or sheltered positions.

What soil does Euphorbia polychroma need?

Euphorbia polychroma grows best in light to moderately fertile loam and sand or chalk soil. It prefers acid and neutral or alkaline soil. Aim for soil that stays well drained; most dislike winter wet.

How do I prune Euphorbia polychroma?

On the shrubby evergreen kinds, cut flowered stems right to the base once the bracts fade in summer, leaving this season's new shoots to flower next year. Cut herbaceous species down in late autumn.

Is Euphorbia polychroma hardy in the UK?

Euphorbia polychroma has an RHS hardiness rating of H4, meaning it is hardy through an average UK winter, tolerating -10 to -5°C.

How do I propagate Euphorbia polychroma?

Divide herbaceous kinds in spring. Take basal cuttings of shrubby species in spring and rinse the cut end to stop the latex sealing it. Many self-seed freely.

Is Euphorbia polychroma toxic?

Irritant sap.

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