Iris sibirica 'Sea Shadows' (Siberian Iris) — Clump-forming, upright

Overview

Iris sibirica 'Sea Shadows' is a clump-forming, upright perennial in the genus Iris, part of the Iridaceae family, with deciduous or evergreen; sword-shaped to grassy, often glaucous foliage. It typically grows around 0.6 m tall and 0.3 m wide. Iris sibirica 'Sea Shadows' grows best in full sun; some tolerate partial shade, and tolerates loam and chalk or sand; sharply drained for bearded kinds soils and neutral to slightly alkaline pH. Its UK hardiness is rated H5–H7.

About

Iris sibirica 'Sea Shadows' is a clump-forming, upright perennial in the Iridaceae with grass-like, often glaucous leaves and a compact habit to roughly 0.6 m high by 0.3 m wide. It flowers from May to July. Give it full sun or light afternoon shade on neutral to slightly alkaline, moisture-retentive soil for best results.

Wikipedia contributors, CC BY-SA 4.0 — Iris sibirica

About the genus

Iris takes its name from the Greek goddess of the rainbow, and for once the naming feels entirely earned. I can't think of another genus that covers so much ground — inky purples, burnt apricots, clean whites, blues that seem lit from inside — or so many situations. There are bearded irises that want their rhizomes baked in full sun, Siberian types happy in ordinary border soil, and species that will sit contentedly at the edge of a pond. What they share is the flower: three petals standing up, three falling away, built with a kind of architectural confidence most plants never attempt. Even out of bloom the foliage earns its place — those upright fans of blue-green leaves hold a border together for months. I grow them for the fortnight in May and June when nothing else in the garden can compete, and I've made my peace with that. Some plants are for the long haul. An iris is an event.

Written by Henry

In the garden

Iris sibirica 'Sea Shadows' is a clump-forming perennial of the iris family that carries the narrow, sword-shaped leaves associated with Siberian and Japanese iris types. It reaches about 0.6 m in height with a spread near 0.3 m and produces its flowering display between May and July. In US terms it corresponds to zones 3–9. Position this cultivar in full sun where possible; some specimens tolerate partial shade, especially on hot sites. A south- or west-facing aspect suits it best. Soil should be neutral to slightly alkaline and can be loam, chalk or sand; while the plant benefits from a free-draining substrate, Siberian types do best when the soil retains some moisture rather than drying out completely. Exposure can be either open or sheltered. In the UK it ranges H5–H7, i.e. hardy to fully hardy across most regions. Use Iris sibirica 'Sea Shadows' in mixed perennial borders, alongside moist path edges or near water features where soil stays consistently damp without becoming waterlogged. The foliage often displays a glaucous bloom through the season, and the plant's May–July flowering gives a clear early-summer run of blooms.

Growing conditions

Best soil and position for Iris

Sunlight: Full sun; some tolerate partial shade
Soil type: Loam, chalk or sand; sharply drained for bearded kinds
Soil pH: Neutral to slightly alkaline
Soil moisture: Well drained; Siberian and Japanese kinds need moisture-retentive soil
Aspect: South or west facing
Exposure: Exposed or sheltered
UK hardiness: H5–H7

Plant details

Iris sibirica 'Sea Shadows' size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright
Foliage: Deciduous or evergreen; sword-shaped to grassy, often glaucous
Height: 0.6 m
Spread: 0.3 m

Care notes

Pruning and caring for Iris sibirica 'Sea Shadows'

Cultivation: Plant bearded irises with the top of the rhizome exposed so it can bake in summer sun; beardless kinds sit just below the surface in richer, damper ground. Feed with a low-nitrogen fertiliser after flowering and keep the rhizomes clear of mulch and encroaching neighbours.
Pruning: Remove spent flower stems at the base. Trim the outer leaves back by about half in late autumn to reduce overwintering fungal spores, leaving the central fan intact.
Propagation: Divide rhizomes six to eight weeks after flowering, discarding the old woody centre and replanting vigorous outer sections. Species come from seed, but named cultivars will not come true.
Pest resistance: Generally trouble-free, though iris sawfly and slugs damage foliage and thrips can disfigure buds.
Disease resistance: Prone to leaf spot, and to rhizome rot wherever drainage is poor or planting too deep.

Frequently asked questions

How do I grow Iris sibirica 'Sea Shadows'?

Plant bearded irises with the top of the rhizome exposed so it can bake in summer sun; beardless kinds sit just below the surface in richer, damper ground. Feed with a low-nitrogen fertiliser after flowering and keep the rhizomes clear of mulch and encroaching neighbours.

Where is the best place to plant Iris sibirica 'Sea Shadows'?

Iris sibirica 'Sea Shadows' prefers full sun; some tolerate partial shade. It suits exposed or sheltered positions.

What soil does Iris sibirica 'Sea Shadows' need?

Iris sibirica 'Sea Shadows' grows best in loam and chalk or sand; sharply drained for bearded kinds soil. It prefers neutral to slightly alkaline soil. Aim for soil that stays well drained; siberian and japanese kinds need moisture-retentive soil.

How do I prune Iris sibirica 'Sea Shadows'?

Remove spent flower stems at the base. Trim the outer leaves back by about half in late autumn to reduce overwintering fungal spores, leaving the central fan intact.

How big does Iris sibirica 'Sea Shadows' grow?

Iris sibirica 'Sea Shadows' reaches a height of 0.6 m and a spread of 0.3 m.

Is Iris sibirica 'Sea Shadows' hardy in the UK?

Iris sibirica 'Sea Shadows' has an RHS hardiness rating of H5, meaning it is hardy in most of the UK, tolerating -15 to -10°C.

How do I propagate Iris sibirica 'Sea Shadows'?

Divide rhizomes six to eight weeks after flowering, discarding the old woody centre and replanting vigorous outer sections. Species come from seed, but named cultivars will not come true.

More in the Iris genus

Browse all Iris →