Blue flag iris
Iris versicolor L.
Also called blue flag iris, northern blue flag.
Native wetland iris with sword-like blue-green leaves and violet-blue flowers veined white and yellow in late spring. Grows in saturated soil and shallow standing water, making it a natural choice for rain-garden bottoms and pond edges.
Size over time
Typical landscape size 0.6–0.9 m (2–3 ft) tall and 0.5–0.6 m (18–24 in) wide; medium growth, about 3 years to maturity. Intermediate sizes use the planner’s growth curve (k = 0.25) from the #1 install size.
Bloom
Blue-violet flowers, May–Jun (northern-hemisphere months; timing shifts with region and season).
| Plant | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Blue flag iris : May–Jun |
Design notes
- Tolerates up to about 10 cm of standing water; in ordinary beds keep it consistently moist.
- Rhizomes and sap are mildly toxic and can irritate skin — wear gloves when dividing.
- Do not substitute yellow flag (Iris pseudacorus), an invasive wetland iris.
Regions
Native range: Eastern Canada and the northeastern U.S., south to Virginia and west to the Great Lakes.
Native to these OpenLandscape3D pilot regions:
Native status describes where the species occurs naturally. It is not a promise that it suits a particular garden; site conditions decide that.
In the guides
Blue flag iris comes up in this guide:
Related plants
Try Blue flag iris in a plan
Opens your own copy of a finished sample garden in the planner with Blue flag iris ready to place; the planner checks it against that garden’s zone, light and moisture.
Plan with Blue flag iris
Place it in a design, check it against your zone, light and moisture, and see it at year three and year ten.