Overview
Iris pseudacorus is a clump forming bogs in the genus Iris, part of the Iridaceae family, with deciduous foliage. It typically grows around 1-1.5 metres tall and 1-1.5 metres wide, reaching full size in around 2-5 years. Iris pseudacorus grows best in full sun and partial shade, and tolerates clay and loam soils and acid pH. Its UK hardiness is rated H7. Suggested uses include borders, rock gardens and containers.
About
Iris pseudacorus, the yellow flag, yellow iris, or water flag, is a species of flowering plant in the family Iridaceae. It is native to Europe, western Asia and northwest Africa. Its specific epithet pseudacorus means "false acorus", referring to the similarity of its leaves to those of Acorus calamus (sweet flag), as they have a prominently veined mid-rib and sword-like shape. However, the two plants are not closely related. It grows to around 1-1.5 metres tall and 1-1.5 metres wide, carrying deciduous foliage. Grow it in full sun and partial shade and clay and loam soil. It tolerates acid soils, poorly-drained conditions and south-facing and east-facing aspects.
Wikipedia contributors, CC BY-SA 4.0 — Iris pseudacorus
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 sun, Partial shade
- Soil type
- Clay, Loam
- Soil pH
- Acid
- Soil moisture
- Poorly-drained
- Aspect
- South-facing, East-facing
- Exposure
- Exposed, Sheltered
- UK hardiness
- H7
Plant details
Iris pseudacorus size, habit and characteristics
- Plant type
- Bogs, Herbaceous Perennial
- Habit
- Clump forming
- Foliage
- Deciduous
- Height
- 1-1.5 metres
- Spread
- 1-1.5 metres
- Time to full height
- 2-5 years
- Suggested uses
- Borders, rock gardens, containers
Care notes
Pruning and caring for Iris pseudacorus
- Propagation
- Division, seed
- Pest resistance
- Aphids, Slugs, Snails
- Disease resistance
- Generally disease-free
Frequently asked questions
Where is the best place to plant Iris pseudacorus?
Iris pseudacorus prefers full sun and partial shade. It suits exposed and sheltered positions.
What soil does Iris pseudacorus need?
Iris pseudacorus grows best in clay and loam soil. It prefers acid soil. Aim for soil that stays poorly-drained.
How big does Iris pseudacorus grow?
Iris pseudacorus reaches a height of 1-1.5 metres and a spread of 1-1.5 metres. It takes around 2-5 years to reach full size.
Is Iris pseudacorus hardy in the UK?
Iris pseudacorus has an RHS hardiness rating of H7, meaning it is fully hardy throughout the UK, tolerating temperatures below -20°C.
How do I propagate Iris pseudacorus?
Division, seed.
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)