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A picture of a Yellow Flag Iris

Yellow Flag Iris

Iris pseudacorus

Also known as

Flag Iris, Pale-Yellow Iris, Water Flag, Yellow Flag, Yellow Flag, Yellow Water Iris, Yellow Iris

Iris pseudacorus 001 by Jean-Jacques MILAN (CC-BY-SA-3.0)

Full Sun
Easy care
Frequent watering
Frost Hardy


USDA zone


Minimum temperature

Expected size








3 years to reach maturity


  • spring
  • summer
  • autumn
  • winter

This plant has no fragrance

More images of Yellow Flag Iris

Some Iris pseudacorus with green leaves and yellow flowers
A yellow Iris pseudacorus flower
Some yellow Iris pseudacorus flowers
Some green Iris pseudacorus plants with yellow flowers in a garden
A photo of Yellow Flag Iris

Yellow Flag Iris Overview

Iris pseudacorus is a herbaceous flowering perennial from the Iridaceae family. It produces tall, blade-like leaves and erect stems with showy flowers that die back completely during winter. Often found in the wild in Northern Europe. This species is native to the British Isles, a common sight in ponds and damp ground. It will produce blooms which are a pale to deep yellow and sometimes have a dark purple or brown zone radiating from the centre of the petals. Flowers measure around 10cm across, they have 3 main large pendant petals, coloured yellow, with attractive brown venation, they appear from mid-summer. Leading onto dry capsule fruits measuring between 4-7cm in length, they contain numerous pale brown seeds. It has a suckering habit and spreads easily. Fully hardy and grows well in full sun or partial shade and moist, poorly-draining soil.

Common problems with Yellow Flag Iris

Yellow Flag Iris Companion Plants

Plant with water loving or bog species.

How to harvest Yellow Flag Iris

Pick flowers in early summer.

How to propagate Yellow Flag Iris


Can be sown in early spring in a cold frame in compost.


Divide anytime from mid-summer to autumn and plant directly into the new location.


Special features of Yellow Flag Iris

Attracts useful insects

Loved by dragonflies and damselflies.

Wet sites

Thrives in margins of ponds, streams or in damp ground.

Attractive flowers

Other uses of Yellow Flag Iris

Bog, aquatic, border, cutting bed.


The root is said to have medicinal properties, but is toxic, so only ever through a medical practitioner.

Water treatment

This plant has been used as a form of water treatment since it has the ability to take up heavy metals through its roots and is featured in many AS Level Biology practicals as its ability to grow in low pH levels makes it a useful indicator.

Marginal Plants

Plants that prefer to grow at the margins of ponds, lakes and waterway.

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