Image for Western Blue Flag Iris

Western Blue Flag Iris

Scientific name

Iris missouriensis


The Western Blue Flag Iris is a long-lived perennial wildflower species that typically grows about 0.5 m tall. This plant may also be known by the common name: Rocky Mountain Iris. The leaves are grayish green, broad, flexible, sword shaped, and appear in dense clumps. The flowers are large, delicate, pale to dark purple coloured, have yellow bases, have distinctive purple veins, appear on the end of stout leafless stalks, and bloom between May and June. The flowers are attractive to pollinator species, like hummingbirds and bees. This plant spreads well and forms dense colonies, which can be divided to grow in other locations. Plant the rhizomes shallowly, just enough so that they are securely in the soil.

Planting conditions

Western Blue Flag Iris grows best in moist to wet conditions with full or partial sun exposure. It prefers well-drained, sand or loam soil types. It prefers early season moisture then drier conditions in late summer. This plant can grow well on slopes with adequate moisture and drainage. It is intolerant of permanently wet conditions and full shade. This is the most drought tolerant native Iris but should have high moisture throughout the spring. This wildflower can be naturally found in marshes, wet meadows, and along stream and lake shorelines.


  • Plant height:
    • Max 1.5m
    • Max 2m
    • Max 3m
    • Any
  • Moisture level:
    • Moist
    • Wet
    • Flood Tolerant
  • Light conditions:
    • Full sun
    • Partial sun
  • Soil type:
    • Sandy
    • Loamy
    • Clay
    • Rocky
  • pH:
    • Normal
  • Depth:
    • Wildflower
  • Eco Zone:
    • 3a
    • 3b
    • 4a
    • 4b
  • Plant type:
    • Wildflower
  • Height:
    • 0.5 m
  • Spread:
    • 1 m