Iris xiphium (Spanish iris) — Clump-forming, upright

Overview

Iris xiphium 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 xiphium 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 W & C Mediterranean.

About

Iris xiphium is a clump-forming, upright perennial in the iris family with sword-shaped leaves that are often glaucous. It produces its flowers in the UK from May to July. Plants prefer a sunny, south- or west-facing position in neutral to slightly alkaline, sharply drained soils. Wear gloves when handling, as the plant is harmful if eaten.

Wikipedia contributors, CC BY-SA 4.0 — Iris xiphium

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 xiphium originates from the western and central Mediterranean and grows as a perennial forming upright clumps. In the UK it flowers from May to July, producing the seasonal display that suits late spring into early summer borders. Leaves are sword-shaped to grassy and are often glaucous; plants may be deciduous or hold foliage longer depending on site. Give the Spanish iris a sunny spot, ideally south- or west-facing, though some plants tolerate light afternoon shade. Soils should be neutral to slightly alkaline — loam, chalk or sandy types are appropriate — and sharply drained where bearded forms occur. Water needs are low once established; avoid waterlogged positions. Hardiness H5–H7 means it tolerates typical UK winters and is suitable for most regions, including exposed sites. Use Iris xiphium in gravel or well-drained mixed borders and on sunny banks where drainage is good. It also performs well in open, exposed situations where northerly cold and poor drainage are not an issue. Handle with care: the plant is harmful if eaten, so wear gloves when planting or dividing, and consult the HTA guide to potentially harmful plants for pet-safety contact information.

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 xiphium size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright
Foliage: Deciduous or evergreen; sword-shaped to grassy, often glaucous
Native to: W & C Mediterranean
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 xiphium

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 xiphium?

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 xiphium?

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

What soil does Iris xiphium need?

Iris xiphium 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 xiphium?

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 xiphium hardy in the UK?

Iris xiphium 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 xiphium?

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 xiphium 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 →