Iris Regeliocyclus Group — Clump-forming, upright

Overview

Iris Regeliocyclus Group 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 Regeliocyclus Group 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 Regeliocyclus Group are clump-forming, upright perennials in the genus Iris, with sword-shaped to grassy foliage that is often glaucous. Plants may be deciduous or evergreen and carry their flowers in late spring to mid-summer. They suit sunny, south- or west-facing positions and can tolerate exposed sites as well as sheltered corners. Flowers appear from May to July.

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 Regeliocyclus Group belong to the Iridaceae family and represent a range of upright, clump-forming irises. Leaves are typically sword-shaped to grassy and often show a glaucous bloom; some types keep foliage through the year while others are deciduous. The group includes forms that respond differently to soil moisture, so read individual labels when selecting varieties. Choose a south- or west-facing site in full sun where possible; some varieties will tolerate partial shade. Soil preferences cover loam, chalk or sand, with neutral to slightly alkaline pH as ideal. Generally plants need a well-drained position, though Siberian and Japanese types within the broader group prefer more moisture-retentive soil. For bearded kinds within the group, sharply drained planting spots are important to avoid rot. Hardiness ranges H5–H7, which means these irises cope from hardy to fully hardy in UK conditions and suit a wide spread of gardens. Exposure can be either exposed or sheltered, so they work on windswept banks as well as in more protected borders built on chalky or gravelly ground. If you are selecting for foliage colour, look for the glaucous leaves; their flowering runs 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 Regeliocyclus Group size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright
Foliage: Deciduous or evergreen; sword-shaped to grassy, often glaucous

Care notes

Pruning and caring for Iris Regeliocyclus Group

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 Regeliocyclus Group?

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 Regeliocyclus Group?

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

What soil does Iris Regeliocyclus Group need?

Iris Regeliocyclus Group 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 Regeliocyclus Group?

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 Regeliocyclus Group hardy in the UK?

Iris Regeliocyclus Group 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 Regeliocyclus Group?

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 →