Overview
Iris ensata is a clump forming herbaceous perennial in the genus Iris, part of the Iridaceae family, with deciduous foliage. It typically grows around 0.5-1 metres tall and 0.1-0.5 metres wide, reaching full size in around 2-5 years. Iris ensata grows best in full shade and partial shade, and tolerates clay and loam soils and acid pH. Its UK hardiness is rated H6. Suggested uses include cottage and informal garden, wildflower meadow and wildlife gardens.
About
Iris ensata, commonly known as Japanese water iris or Japanese flag, is a clump-forming herbaceous perennial in the Iridaceae family. It features deciduous foliage and typically grows to a height of 0.5 to 1 metre with a spread of 0.1 to 0.5 metres, reaching full height within 2 to 5 years. This cultivar thrives in full or partial shade, favouring south, east, or west-facing aspects, and can tolerate both exposed and sheltered conditions. It prefers poorly-drained, acid soils such as clay or loam and provides seasonal interest throughout spring, summer, autumn, and winter.
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
Growing conditions
Best soil and position for Iris
- Sunlight
- Full shade, Partial shade
- Soil type
- Clay, Loam
- Soil pH
- Acid
- Soil moisture
- Poorly-drained
- Aspect
- South-facing, East-facing, West-facing
- Exposure
- Exposed, Sheltered
- UK hardiness
- H6
Plant details
Iris ensata size, habit and characteristics
- Plant type
- Herbaceous Perennial
- Habit
- Clump forming
- Foliage
- Deciduous
- Height
- 0.5-1 metres
- Spread
- 0.1-0.5 metres
- Time to full height
- 2-5 years
- Suggested uses
- Cottage and informal garden, Wildflower meadow, Wildlife gardens
Care notes
Pruning and caring for Iris ensata
- Propagation
- Division of rhizomes from midsummer to early autumn
- Pest resistance
- Slugs, Snails, Thrips
- Disease resistance
- Aphid-borne viruses, Bacterial soft rot, Grey moulds
Frequently asked questions
Where is the best place to plant Iris ensata?
Iris ensata prefers full shade and partial shade. It suits exposed and sheltered positions.
What soil does Iris ensata need?
Iris ensata grows best in clay and loam soil. It prefers acid soil. Aim for soil that stays poorly-drained.
How big does Iris ensata grow?
Iris ensata reaches a height of 0.5-1 metres and a spread of 0.1-0.5 metres. It takes around 2-5 years to reach full size.
Is Iris ensata hardy in the UK?
Iris ensata has an RHS hardiness rating of H6, meaning it is very hardy, tolerating -20 to -15°C across most of the UK.
How do I propagate Iris ensata?
Division of rhizomes from midsummer to early autumn.
More in the Iris genus
- Iris 'Antigone' (TB)
- Iris 'Dauntless' (TB)
- Iris 'Dipped in Dots' (TB)
- Iris 'Ablaze' (MDB)
- Iris 'After the Storm' (TB)
- Iris 'Aldo Ratti' (TB)
- Iris 'Alene's New Love' (SDB)iris 'Alene's New Love'
- Iris 'Alpine Lake' (MDB)
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