Yellow flag iris (Iris pseudacorus) is classified as a Class C noxious weed in Washington State. 

This means it’s a non-native, potentially harmful plant that landowners may be required to control based on local priorities. While control is not mandated across the state, it is recommended due to its aggressive spread and ability to outcompete native vegetation. 

It will sicken livestock if ingested and is generally avoided by herbivores. Contact with its resins can cause skin irritation in humans. Washington State Noxious Weed Control Board (LINK)

In accordance with WAC 16-750, control is required when a Class C is selected by a local weed board. Thurston County Noxious Weed List (LINK)

Do not plant yellow flag iris in your landscape. If you already have yellow flag iris, please consider removing it and re-planting the area with native vegetation. Thurston County Noxious Weed Control Board (LINK)

More Resources About Yellow Flag Iris

LAKE LAWRENCE VIDEO: Yellow Flag Iris is Dangerous – Control It! LINK

LAKE LAWRENCE VIDEO: Yellow Flag Iris control is your responsibility. LINK

PDF: Thurston County Noxious Weed Facet Sheet LINK

PDF: Control Options for Yellow Flag Iris LINK

OFFUT LAKE NEWS POST: April 2024: Help Remove Yellow Flag Iris LINK

OFFUT LAKE NEWS POST August 2024:  Yellow Flag Iris LINK

LONG LAKE WEB POST June 2024: Yellow Flag Iris: A Beautiful but Risky Choice for Your Yard and Lakefront LINK