Iris foetidissima 'Chinese Form' of gardens (Stinking Iris) — Clump-forming, upright

Overview

Iris foetidissima 'Chinese Form' of gardens 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 'Chinese Form' of gardens 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 foetidissima 'Chinese Form' of gardens is a clump-forming, upright perennial in the Iridaceae, notable for its unpleasant, foetid scent. It grows to about 1.0 m with sword-shaped, often glaucous leaves that may be deciduous or persist through winter. Flowers are leaden-blue to buff-yellow tinged with blue and appear from May to July. It suits full sun or some partial shade on well-drained, neutral to slightly alkaline soils and prefers a south or west-facing aspect.

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 'Chinese Form' of gardens is a garden form of Iris in the Iridaceae, valued for its architectural, sword-like leaves and an unusual, foetid fragrance. The plant forms upright clumps, reaching about 1.0 m, and produces flowers from May to July. Flowering colours range from leaden-blue to buff-yellow tinged with blue. Plant on a south or west-facing slope or border in full sun or where it receives some light shade. It favours neutral to slightly alkaline soil and performs best in loam, chalk or sand provided the soil is sharply drained for bearded types; generally it prefers well-drained conditions. In UK hardiness terms it sits in H5–H7 (hardy to fully hardy) and corresponds roughly to USDA zones 3–9, so it will tolerate most garden winters across Britain. Place the clump at the middle or rear of a mixed border where its 1.0 m height provides structure without overwhelming lower plants. It will grow in exposed or sheltered positions; bear the foliage scent in mind when siting near patios or seating. The plant's erect habit and long-lived foliage give winter structure even when not in flower.

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 'Chinese Form' of gardens 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
Fragrance: Unpleasant, foetid

Care notes

Pruning and caring for Iris foetidissima 'Chinese Form' of gardens

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 'Chinese Form' of gardens?

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 'Chinese Form' of gardens?

Iris foetidissima 'Chinese Form' of gardens prefers full sun; some tolerate partial shade. It suits exposed or sheltered positions.

What soil does Iris foetidissima 'Chinese Form' of gardens need?

Iris foetidissima 'Chinese Form' of gardens 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 'Chinese Form' of gardens?

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 'Chinese Form' of gardens grow?

Iris foetidissima 'Chinese Form' of gardens reaches a height of 1.0 m.

Is Iris foetidissima 'Chinese Form' of gardens hardy in the UK?

Iris foetidissima 'Chinese Form' of gardens 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 'Chinese Form' of gardens?

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 →