Iris aurea — Clump-forming, upright

Overview

Iris aurea 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. Iris aurea 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 aurea is a clump-forming, upright perennial in the iris family with sword-shaped leaves that are often glaucous. It flowers from May to July. Plant in full sun or with light afternoon shade on neutral to slightly alkaline loam, chalk or sand with good drainage. It is winter-hardy across most of the UK (H5–H7) when given a south- or west-facing position.

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

A member of the Iridaceae, Iris aurea grows as an upright, clump-forming perennial with sword-shaped to grassy leaves that commonly show a glaucous bloom. Flowering takes place from May to July, providing a clear early-summer display while the foliage supplies structure before and after bloom. Give Iris aurea a sunny aspect, ideally south- or west-facing; some specimens will tolerate light afternoon shade. It prefers neutral to slightly alkaline soils—loam, chalk or sand are all suitable—combined with good drainage. Bearded irises in the wider genus benefit from sharply drained soils, while groups such as Siberian and Japanese irises do better in moisture-retentive ground, so choose planting companions and a site to match. Hardiness ratings of H5–H7 mean this species withstands typical UK winters from milder southern districts through colder areas. Use it in sunny mixed borders, on gravel banks or at the front of perennial beds where the erect leaves form architectural lines. The glaucous, sword-shaped foliage remains upright well beyond the May to July flowering period.

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 aurea size, habit and characteristics

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

Care notes

Pruning and caring for Iris aurea

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 aurea?

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 aurea?

Iris aurea prefers full sun; some tolerate partial shade. It suits exposed or sheltered positions.

What soil does Iris aurea need?

Iris aurea 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 aurea?

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.

Is Iris aurea hardy in the UK?

Iris aurea 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 aurea?

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 →