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Invasive Plant: Common Reed

Photo shows grass plants along a river bank with a blue sky.
Common reed is harmful to wetlands and estuaries, which are very important habitats. Wetlands and estuaries help clean our water and provide food and safe places for many of Oregon’s birds and animals. Once common reed is in these habitats, they are no longer good places to live.
On this page

At a Glance

  • Scientific name:Phragmites australis ssp. australis
  • Annual, perennial, or biennial: Perennial
  • Conditions it likes best: Moist, wet soil. Common reed likes places with shallow water such as roadside ditches, marshes, estuaries, and wetlands.
  • How it spreads: Primarily by roots and stems that creep along the ground to root and form new plants. Seeds can also spread by wind and water or by attaching to people and animals.
  • How it causes damage: Common reed damages wetlands and estuaries where it takes the place of other plants, reducing biodiversity. Oregon’s wetlands and estuaries provide the food and shelter that many of the state’s birds and animals need to survive. Common reed can destroy this critical habitat.
  • Oregon Department of Agriculture noxious weed rank: B
  • Report patches of this plant? Yes. City code lists this as a Required Eradication species. Report all sightings to Environmental Services. Contact information is on this page. Management of this species is required, but free help is available.

How to Identify Common Reed

  • Photo shows grass-like plant with long, feathery leaves against a blue sky.

    Common reed is on the Required Eradication List. Photos by Glenn Miller, Oregon Department of Agriculture.
    Spring–Summer. Plants emerge in April and May. The large grass plants have woody, hollow stems and can grow from 3 to 13 feet tall. Flowering stalks have large feathery flowers.
  • Fall–Winter. Seeds form in late summer and early fall. From November through January, seeds are spread by wind and water or by attaching to people and animals.

How and When to Remove Common Reed

  • Manual. For very small  patches, digging probably works, but not for larger patches.  
  • Herbicide. Herbicide treatments  work best in mid- to late summer (from June to August).
  • Check. Check the site for new plants at least once a year, and especially for the first 2-3 years after removal.
  • Replant. After a year or two of managing this plant, consider planting native or less aggressive non-native plants.

Prevention is Best Practice

Clean your boots, pets, and maybe even your tires when you finish a hike or trail ride in Pacific Northwest natural areas, or if you have invasive plants on your own property. Cleaning boots and pets keeps invasive plants from spreading to new places.  Be careful when trading plants with neighbors and fellow gardeners to make sure you’re not trading this or any other plant of concern.  

Be Aware of Look-alikes

In the Portland metro area, there is a rare subspecies of common reed that is very difficult to distinguish from the invasive subspecies. If you think you may have found common reed, check with the Oregon Department of Agriculture to confirm before trying to remove it.

Giant reed (Arundo donax) is another very tall grass that should also be reported.

Properly Dispose of Invasive Plants

To prevent spreading invasive plants:

  • Never place plants or seeds in your compost or yard debris.
  • Never throw pulled plants on the ground or into the street or sidewalk.
  • Put all pulled plants, bulbs, or seeds into a plastic bag and put the bag in the trash.
  • Wash all garden tools and gloves.