Iris x robusta 'Dark Aura' — Clump-forming

Overview

Iris x robusta 'Dark Aura' is a plant with a clump-forming habit in the genus Iris, part of the Iridaceae family, with sword-shaped foliage. Iris x robusta 'Dark Aura' grows best in full sun, and tolerates loam soils and neutral pH. Its UK hardiness is rated H7. Suggested uses include borders, rock gardens and containers.

About

Iris x robusta 'Dark Aura' is a clump-forming iris in the Iridaceae with sword-shaped foliage and an upright habit. It flowers in the UK from May to July. The plant prefers full sun on neutral loam in south-facing, sheltered sites. It is suited to borders, rock gardens and containers.

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 x robusta 'Dark Aura' is a clump-forming member of the Iridaceae grown for its seasonal display of flowers between May and July and for the architectural presence of its sword-shaped leaves. The botanical name indicates its placement within the genus Iris and the cultivar epithet distinguishes this garden form from other robusta types. Position the plant in full sun, ideally in a south-facing, sheltered spot where it will avoid cold exposure and drying winds. Use a neutral loam that is well drained: the combination of pH and soil texture supports healthy root development while avoiding waterlogged conditions. Exposure should be sheltered rather than exposed. This cultivar carries a UK hardiness rating of H7, which translates to fully hardy under typical UK winter conditions. It therefore suits permanent planting in outdoor beds as well as large containers that receive a sheltered, sunny aspect. Place it in mixed borders where the upright clump of sword-shaped foliage can provide structure, or use it in rock garden pockets and containers where soil can be maintained as a neutral, loam-based medium. Expect the flowering season to run from May to July, giving a clear early-summer window of bloom for planning adjacent plants.

Growing conditions

Best soil and position for Iris

Sunlight: Full sun
Soil type: Loam
Soil pH: Neutral
Soil moisture: Well-drained
Aspect: South-facing
Exposure: Sheltered
UK hardiness: H7

Plant details

Iris x robusta 'Dark Aura' size, habit and characteristics

Habit: Clump-forming
Foliage: Sword-shaped
Suggested uses: Borders, rock gardens, containers

Care notes

Pruning and caring for Iris x robusta 'Dark Aura'

Propagation: Division, seed
Pest resistance: High
Disease resistance: High

Frequently asked questions

Where is the best place to plant Iris x robusta 'Dark Aura'?

Iris x robusta 'Dark Aura' prefers full sun. It suits sheltered positions.

What soil does Iris x robusta 'Dark Aura' need?

Iris x robusta 'Dark Aura' grows best in loam soil. It prefers neutral soil. Aim for soil that stays well-drained.

Is Iris x robusta 'Dark Aura' hardy in the UK?

Iris x robusta 'Dark Aura' has an RHS hardiness rating of H7, meaning it is fully hardy throughout the UK, tolerating temperatures below -20°C.

How do I propagate Iris x robusta 'Dark Aura'?

Division, seed.

More in the Iris genus

Browse all Iris →