Iris orientalis (Turkish iris) — Clump-forming, upright

Overview

Iris orientalis 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 orientalis 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. It is native to Greece and Turkey.

About

Iris orientalis is a clump-forming, upright perennial with sword-shaped foliage that is often glaucous. It flowers in the UK from May to July. Plants prefer full sun and neutral to slightly alkaline, well-drained soils. Wear gloves and other protective equipment when handling as the plant is harmful if eaten; pets are also at risk.

Wikipedia contributors, CC BY-SA 4.0 — Iris orientalis

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 orientalis originates from Greece and Turkey and grows as a clump-forming, upright perennial. In the UK it reliably produces its flowering stems in May to July, giving a late-spring to mid-summer presence in the border. Position plants in full sun on a south or west-facing site; some plants will tolerate light afternoon shade. Soils should be neutral to slightly alkaline: loam, chalk or sand are all suitable provided drainage is good. Exposure is not critical — it tolerates both sheltered and more exposed sites — and its UK hardiness rating of H5–H7 means it is hardy across most of the country, with H5 = hardy, H6 = very hardy and H7 = fully hardy. The USDA hardiness range is 3–9. Handle with care, as all parts are harmful if eaten; wear gloves and other protective equipment when working with plants and note that they are harmful to pets — for further information and contact numbers consult the HTA guide to potentially harmful plants. Place Iris orientalis where its erect habit and seasonal flowering will be seen from paths or seating areas, and expect the main display in the May to July 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 orientalis size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright
Foliage: Deciduous or evergreen; sword-shaped to grassy, often glaucous
Native to: Greece, Turkey
Toxicity: Harmful if eaten. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants

Care notes

Pruning and caring for Iris orientalis

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 orientalis?

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 orientalis?

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

What soil does Iris orientalis need?

Iris orientalis 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 orientalis?

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 orientalis hardy in the UK?

Iris orientalis 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 orientalis?

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.

Is Iris orientalis toxic?

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

More in the Iris genus

Browse all Iris →