Iris fulva (tawny iris) — Clump-forming, upright

Overview

Iris fulva 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 fulva 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 southern and central United States.

About

Iris fulva is a clump-forming, upright perennial best known for its copper to deep red flowers. Leaves are sword-shaped to grassy and often show a glaucous bloom, and the foliage may be deciduous or persist through winter. It flowers in the UK from May to July. Plant where it receives full sun or light afternoon shade on neutral to slightly alkaline, well-drained soil.

Wikipedia contributors, CC BY-SA 4.0 — Iris fulva

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 fulva is a perennial iris native to the southern and central United States, valued for its copper to deep red blooms. It grows as an upright, clump-forming plant with sword-shaped to grassy leaves that are often glaucous and can be either deciduous or evergreen in appearance. Flowering occurs from May to July in the UK, when the coloured standards and falls make the species unmistakable in a border. Give the plant a sunny position — south or west facing is best — although some plants tolerate light afternoon shade. It favours neutral to slightly alkaline soils such as loam, chalk or sand, and performs on soils that are kept well drained. Exposure can be either exposed or sheltered; hardiness is H5–H7 (hardy to fully hardy), and the USDA range of 3–9 shows why it tolerates a broad range of conditions where winters are not extreme. Where space allows, Iris fulva suits sunny perennial borders, gravel or mixed-drainage beds where its upright clumps can be appreciated. Handle with care: the plant is harmful if eaten, and gloves and other protective equipment should be worn when handling; for pet guidance consult the HTA guide to potentially harmful plants. The copper-to-deep-red flowers stand out against the glaucous foliage from May to July.

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 fulva size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright
Foliage: Deciduous or evergreen; sword-shaped to grassy, often glaucous
Native to: southern and central United States
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 fulva

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 fulva?

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 fulva?

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

What soil does Iris fulva need?

Iris fulva 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 fulva?

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 fulva hardy in the UK?

Iris fulva 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 fulva?

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 fulva 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 →