Yellow Flag Iris

Yellow flag iris brings upright, sword-shaped leaves and clear yellow flowers to wet margins, where its bold spring and early-summer display can be striking. It is also a vigorous rhizomatous plant that can spread beyond a garden, so site choice and local rules matter. ## Site and character The North Carolina Extension profile describes yellow flag as a water plant for full sun and persistently moist, occasionally flooded or standing-water sites. Flowers are yellow and typically appear from spring into summer; capsules release many seeds. It suits a contained pond edge or purpose-built rain garden only where it can be controlled. ## Regional caution Yellow flag is listed as invasive by the North Carolina Invasive Plant Council, and Wisconsin DNR describes it as an invasive wetland species. Its status and restrictions vary by region, so check local guidance before planting and avoid disposal where seeds or rhizomes could reach waterways. The North Carolina profile also reports low toxicity to people and problems for cats, dogs, and horses. [North Carolina Extension](https://plants.ces.ncsu.edu/plants/iris-pseudacorus/common-name/yellow-flag/) · [Wisconsin DNR](https://dnr.wisconsin.gov/topic/Invasives/fact/YellowFlagIris) ## Maintenance Keep growth within a contained area and remove unwanted seed heads before capsules mature. Divide or remove rhizomes when the clump outgrows its space, disposing of plant material according to local invasive-species guidance.