Growing Guide
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Iris, Yellow Flag

Herbaceous Perennial Flower

Iris pseudoacorus
Iridaceae Family

At home in bog gardens and other soggy sites, this aggressive perennial has cheerful yellow blooms and stiff, erect dark green foliage.

Site Characteristics
  • full sun

Soil conditions:

  • requires damp soil
  • Tolerates poor drainage
Performs best when roots are submerged in water or at least receive constant moisture.

Hardiness zones:

  • 5 to 9
Plant Traits

Lifecycle: perennial

Ease-of-care: easy

Height: 3 to 5 feet

Spread: 2 to 2.5 feet

Bloom time:

  • late spring
  • early summer

Flower color: yellow

Blooms are vivid yellow with gold veining.

Foliage color: dark green

Foliage texture: medium


  • cushion, mound or clump
  • upright
  • fan-shaped

Shape in flower: flower stalks with upright spikes

Flowers borne along erect stems rising above the foliage.

Special Considerations
Special characteristics:
  • aggressive - Self-seeds prolifically if not deadheaded.
  • non-invasive
  • not native to North America - Native to Europe and North Africa.
Growing Information
How to plant:

Propagate by seed, division or separation - Divide in the spring or fall. Often self-sows.

Maintenance and care:
Deadhead after flowering to prevent self sowing. Divide in the spring or fall as needed.

More growing information: How to Grow Perennials

Iris borer in dry sites
‘Bastardii’ (var. bastardii) has flowers that are creamy yellow, lacking the usual brown blotch on the falls (or lower flower parts).

‘Flore Pleno’: double yellow blooms.

‘Golden Queen’ produces somewhat larger yellow flowers, which also lack the brown splotch.

‘Variegata’: yellow flowers on plants with yellow variegation on green leaves.