Euphorbia robbiae — Clump-forming, upright or spreading sub-shrub

Overview

Euphorbia robbiae 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. It typically grows around 0.8 metres tall. Euphorbia robbiae 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 Italy.

About

Euphorbia robbiae is a clump-forming perennial spurge with narrow, often glaucous leaves and a compact habit to about 0.8 metres. It flowers from May to September and carries a milky sap that can irritate skin. Native to Italy, it suits a range of light garden soils provided drainage is good. Plants may be evergreen, semi-evergreen or briefly deciduous depending on site and season.

Wikipedia contributors, CC BY-SA 4.0 — Euphorbia amygdaloides

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 robbiae belongs to the Euphorbiaceae and originates from Italy. It forms upright or spreading clumps to roughly 0.8 metres and typically bears narrow, blue-grey (glaucous) foliage that can take on red tints in autumn. Flowering occurs from May to September. Give it full sun to partial shade; woodland strains tolerate dry shade, so it will sit comfortably beneath trees that do not leave the soil waterlogged. It prefers light to moderately fertile loam, sand or chalk on soils that are well drained — most plants dislike winter wet. Soil pH may be acid, neutral or alkaline, and the species handles exposed or sheltered positions and a variety of aspects. Hardiness is H4–H7 (average to fully hardy), so Euphorbia robbiae survives UK winters across most regions. Use it where a clump-forming, low sub-shrub suits the planting — gravel, edge of mixed borders, or dry-shade under trees are all appropriate. Handle and prune with care: the milky sap is an irritant, so wear gloves and eye protection when cutting back after flowering in late summer.

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 robbiae 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
Height: 0.8 metres
Native to: Italy
Toxicity: Irritant sap

Care notes

Pruning and caring for Euphorbia robbiae

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 robbiae?

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 robbiae?

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

What soil does Euphorbia robbiae need?

Euphorbia robbiae 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 robbiae?

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.

How big does Euphorbia robbiae grow?

Euphorbia robbiae reaches a height of 0.8 metres.

Is Euphorbia robbiae hardy in the UK?

Euphorbia robbiae 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 robbiae?

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 robbiae toxic?

Irritant sap.

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