Helleborus × sternii (Stern's hybrid hellebore) — Clump-forming, mounded

Overview

Helleborus × sternii is a clump-forming, mounded perennial in the genus Helleborus, part of the Ranunculaceae family, with evergreen or semi-evergreen; leathery, palmately divided, dark green foliage. Helleborus × sternii grows best in partial shade; tolerates full sun in reliably moist soil, and tolerates fertile heavy loam or clay with plenty of humus soils and neutral to alkaline pH. Its UK hardiness is rated H6-H7. Suggested uses include borders, woodland gardens, shaded garden beds and under deciduous shrubs..

About

Helleborus × sternii is a clump-forming, mounded perennial in the ranunculus family that produces its flowers in winter and early spring. It has leathery, palmately divided dark green leaves that remain through much of the year. Flowers appear from January to April. Wear gloves when handling as the plant is harmful if eaten and can cause skin irritation.

About the genus

Commonly known as hellebores, the Eurasian genus Helleborus consists of approximately 20 species of herbaceous or evergreen perennial flowering plants in the family Ranunculaceae, within which it gave its name to the tribe of Helleboreae. Many hellebore species are poisonous.

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

In the garden

Helleborus × sternii is a garden hybrid within the genus Helleborus (family Ranunculaceae) that combines the winter-flowering habit of hellebores with a compact, mounded growth. It flowers from January to April, providing one of the earlier sources of blooms after the winter months. The foliage is leathery and palmately divided, remaining evergreen or semi-evergreen in suitable sites. Give this hellebore partial shade or an east-, north- or west-facing position; it will tolerate full sun only where the soil remains reliably moist. Plant into fertile heavy loam or clay that has plenty of humus, on a neutral to alkaline pH. Keep the soil moist but well drained and choose a sheltered spot to reduce winter wind exposure. In UK hardiness terms it ranges from H6 to H7, meaning it is very hardy to fully hardy across most gardens. Use Helleborus × sternii in mixed borders, shaded beds and woodland-style plantings or beneath deciduous shrubs where its evergreen leaves form a low mound under taller plants. Take care when planting where pets or children might nibble foliage; for further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants. Remove worn flowering stems carefully to avoid skin contact with the sap.

Growing conditions

Best soil and position for Helleborus

Sunlight: Partial shade; tolerates full sun in reliably moist soil
Soil type: Fertile heavy loam or clay with plenty of humus
Soil pH: Neutral to alkaline
Soil moisture: Moist but well drained
Aspect: North, east or west facing
Exposure: Sheltered
UK hardiness: H6-H7

Plant details

Helleborus × sternii size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, mounded
Foliage: Evergreen or semi-evergreen; leathery, palmately divided, dark green
Suggested uses: Borders, woodland gardens, shaded garden beds, under deciduous shrubs.
Toxicity: Harmful if eaten, skin irritant. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten, skin irritant. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants

Care notes

Pruning and caring for Helleborus × sternii

Cultivation: Give them a cool, humus-rich root run under deciduous shrubs, where they get spring light and summer shade. They dislike being moved, so plant well and then leave alone. The single most useful job is removing the old leaves of the hybrid hellebores in midwinter: it exposes flowers that would otherwise be hidden, and strips out the foliage that carries leaf spot.
Pruning: Cut away the previous season's leaves of stemless kinds as the flower buds emerge in midwinter. On stemmed species such as H. foetidus and H. argutifolius, remove flowered stems at the base once they fade.
Propagation: Divide established clumps after flowering, though they re-establish slowly. Seed sown fresh germinates readily and self-sown seedlings are plentiful, but hybrids will vary from the parent.
Pest resistance: Slugs and snails damage emerging buds, and aphids gather on flower stems in spring.
Disease resistance: Hellebore leaf spot is common and disfiguring, and removing old foliage in winter is the main control. Hellebore black death, a virus, causes distorted blackened growth and affected plants must be destroyed.

Frequently asked questions

How do I grow Helleborus × sternii?

Give them a cool, humus-rich root run under deciduous shrubs, where they get spring light and summer shade. They dislike being moved, so plant well and then leave alone. The single most useful job is removing the old leaves of the hybrid hellebores in midwinter: it exposes flowers that would otherwise be hidden, and strips out the foliage that carries leaf spot.

Where is the best place to plant Helleborus × sternii?

Helleborus × sternii prefers partial shade; tolerates full sun in reliably moist soil. It suits sheltered positions.

What soil does Helleborus × sternii need?

Helleborus × sternii grows best in fertile heavy loam or clay with plenty of humus soil. It prefers neutral to alkaline soil. Aim for soil that stays moist but well drained.

How do I prune Helleborus × sternii?

Cut away the previous season's leaves of stemless kinds as the flower buds emerge in midwinter. On stemmed species such as H. foetidus and H. argutifolius, remove flowered stems at the base once they fade.

Is Helleborus × sternii hardy in the UK?

Helleborus × sternii has an RHS hardiness rating of H6, meaning it is very hardy, tolerating -20 to -15°C across most of the UK.

How do I propagate Helleborus × sternii?

Divide established clumps after flowering, though they re-establish slowly. Seed sown fresh germinates readily and self-sown seedlings are plentiful, but hybrids will vary from the parent.

Is Helleborus × sternii toxic?

Harmful if eaten, skin irritant. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten, skin irritant. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants.

More in the Helleborus genus

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