Iris foetidissima (stinking iris) — Clump-forming, upright

Overview

Iris foetidissima 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 1.0 m tall. Iris foetidissima 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. Suggested uses include ornamental garden plant, woodland garden and naturalizing in shaded areas. It is native to Europe and N Africa.

About

Iris foetidissima is a clump-forming, upright perennial in the Iridaceae noted for its unpleasant, foetid-smelling foliage when bruised. It reaches about 1.0 m and carries sword-shaped, often glaucous leaves. Flowering occurs in the UK from May to July, with blooms produced above the foliage. The plant is used in woodland and shaded areas and can naturalise where conditions suit it.

Wikipedia contributors, CC BY-SA 4.0 — Iris foetidissima

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 foetidissima is a perennial native to parts of Europe and North Africa, forming upright clumps of sword-shaped leaves that are often glaucous in tone. Its foliage emits an unpleasant, foetid smell if crushed or handled, which is a useful identification feature rather than a reason to remove it. Give it a sunny site where possible — full sun is preferred, though some plants tolerate partial shade — on a south or west-facing aspect. It performs best in neutral to slightly alkaline soils that are well drained; loam, chalk or sand are suitable soil types. The species is hardy (H5–H7), so it will withstand most UK conditions from milder lowlands to exposed situations. Exposure can be exposed or sheltered without major problems. Use Iris foetidissima as a structural perennial in mixed borders, in a woodland garden or to naturalise in shaded corners where its upright habit and seasonal flowers are appreciated. Take care when handling: the plant is harmful if eaten and protective gloves are advised when lifting or dividing. Expect the leaf scent to be noticeable if foliage is brushed or crushed.

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 foetidissima size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright
Foliage: Deciduous or evergreen; sword-shaped to grassy, often glaucous
Height: 1.0 m
Suggested uses: ornamental garden plant, woodland garden, naturalizing in shaded areas
Native to: Europe, N Africa
Fragrance: unpleasant, foetid smell
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 foetidissima

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 foetidissima?

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 foetidissima?

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

What soil does Iris foetidissima need?

Iris foetidissima 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 foetidissima?

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 foetidissima grow?

Iris foetidissima reaches a height of 1.0 m.

Is Iris foetidissima hardy in the UK?

Iris foetidissima 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 foetidissima?

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 foetidissima 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 →