Crocosmia × crocosmiiflora 'Walburton Yellow' (Montbretia) — Clump-forming, upright with arching flower sprays

Overview

Crocosmia × crocosmiiflora 'Walburton Yellow' is a clump-forming, upright with arching flower sprays perennial in the genus Crocosmia, part of the Iridaceae family, with deciduous; stiff, pleated, sword-shaped, mid to bright green foliage. Crocosmia × crocosmiiflora 'Walburton Yellow' grows best in full sun to partial shade, and tolerates fertile and moisture-retentive loam improved with organic matter soils and acid and neutral or alkaline pH. Its UK hardiness is rated H4-H6. Suggested uses include borders, cut flowers, cottage gardens and naturalizing in moisture-retentive soil..

About

Crocosmia × crocosmiiflora 'Walburton Yellow' is a clump-forming perennial in the iris family with an upright habit and arching flower sprays. Leaves are deciduous, stiff, pleated and sword-shaped in mid to bright green. It flowers from July to September. Plant in fertile, moisture-retentive loam in a sheltered, south, west or east-facing spot in full sun to partial shade.

About the genus

Crocosmia, also known as montbretia, is a small genus of flowering plants in the iris family, Iridaceae. It is native to the grasslands of southern and eastern Africa, ranging from South Africa to Sudan. One species is endemic to Madagascar.

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

In the garden

Crocosmia × crocosmiiflora 'Walburton Yellow' is a clump-forming perennial in the Iridaceae with an upright habit and arching sprays of summer blooms. The foliage is deciduous, with stiff, pleated, sword-shaped leaves that provide a structural presence through the growing season. Flowering occurs from July to September. Position it in full sun to partial shade on fertile, moisture-retentive loam improved with organic matter; it tolerates acid, neutral or alkaline soils. Soils should be moist but well drained and the plant prefers a sheltered aspect on south, west or east-facing borders. Its UK hardiness is H4–H6, which corresponds to average to very hardy conditions across much of Britain where winter temperatures are moderate to cold. Use Crocosmia × crocosmiiflora 'Walburton Yellow' towards the back of mixed borders, in cottage-style beds or for cutting, and allow it to naturalise where soil remains moisture-retentive. The arching flower sprays sit well above lower perennials, so place it where the blooms can be seen rather than obscured by taller neighbours; it reliably flowers through the peak summer months from July to September.

Growing conditions

Best soil and position for Crocosmia

Sunlight: Full sun to partial shade
Soil type: Fertile, moisture-retentive loam improved with organic matter
Soil pH: Acid, neutral or alkaline
Soil moisture: Moist but well drained
Aspect: South, west or east facing
Exposure: Sheltered
UK hardiness: H4-H6

Plant details

Crocosmia × crocosmiiflora 'Walburton Yellow' size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright with arching flower sprays
Foliage: Deciduous; stiff, pleated, sword-shaped, mid to bright green
Suggested uses: Borders, cut flowers, cottage gardens, naturalizing in moisture-retentive soil.

Care notes

Pruning and caring for Crocosmia × crocosmiiflora 'Walburton Yellow'

Cultivation: Plant corms in spring rather than autumn, setting them around 10cm deep in ground that holds summer moisture, since drought during bud formation is what produces a poor showing. Clumps become congested within a few years and flowering falls away, so lift and divide regularly. The most vigorous kinds spread strongly and are best kept away from delicate neighbours; in colder gardens a dry winter mulch protects the corms.
Pruning: Remove faded flower stems, or leave the seed capsules for autumn interest. Cut the foliage down once it has yellowed in late autumn, or leave it as crown protection and clear in early spring.
Propagation: Divide congested clumps in spring, separating the chains of corms and replanting the plump upper ones. Species can be raised from seed.
Pest resistance: Little troubled outdoors; red spider mite occurs on plants under glass, and slugs graze new shoots.
Disease resistance: Robust in suitable conditions. Gladiolus rust and corm rot occur occasionally, the latter where drainage is poor.

Frequently asked questions

How do I grow Crocosmia × crocosmiiflora 'Walburton Yellow'?

Plant corms in spring rather than autumn, setting them around 10cm deep in ground that holds summer moisture, since drought during bud formation is what produces a poor showing. Clumps become congested within a few years and flowering falls away, so lift and divide regularly. The most vigorous kinds spread strongly and are best kept away from delicate neighbours; in colder gardens a dry winter mulch protects the corms.

Where is the best place to plant Crocosmia × crocosmiiflora 'Walburton Yellow'?

Crocosmia × crocosmiiflora 'Walburton Yellow' prefers full sun to partial shade. It suits sheltered positions.

What soil does Crocosmia × crocosmiiflora 'Walburton Yellow' need?

Crocosmia × crocosmiiflora 'Walburton Yellow' grows best in fertile and moisture-retentive loam improved with organic matter soil. It prefers acid and neutral or alkaline soil. Aim for soil that stays moist but well drained.

How do I prune Crocosmia × crocosmiiflora 'Walburton Yellow'?

Remove faded flower stems, or leave the seed capsules for autumn interest. Cut the foliage down once it has yellowed in late autumn, or leave it as crown protection and clear in early spring.

Is Crocosmia × crocosmiiflora 'Walburton Yellow' hardy in the UK?

Crocosmia × crocosmiiflora 'Walburton Yellow' 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 Crocosmia × crocosmiiflora 'Walburton Yellow'?

Divide congested clumps in spring, separating the chains of corms and replanting the plump upper ones. Species can be raised from seed.

More in the Crocosmia genus

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