Weeds: Reed canarygrass – Phalaris arundinacea

categories: Pr-Sc Weeds

revision date: 2024-06-22 11:00

  • Family: Poaceae (Graminae)
  • Cycle: Perennial
  • Plant type: Grass
Reed canarygrass emerging in spring.
Reed canarygrass emerging in spring
Photo by: B.M. Johnson


An aggressive plant, reed canarygrass grows from a large root system. It spreads rapidly by seeds and rhizomes to form large, dense patches, effectively crowding out other plants. The stems are two to seven feet tall. Leaves are flat, but rolled in the bud before emerging. Leaf blades are 1/4 to 3/4 inch wide, three to eight inches long, and tapering to a pointed tip. The leaf edges are rough. The ligule (found at the point where the leaf blade joins the leaf sheath) is an obvious membrane 1/5 to 1/2-inch long. The leaf sheaths are membranous along the edges. Seeds are borne in a dense panicle or seed head, which appears to be branched at the bottom and unbranched above. The panicles are closed and compact initially, but open at maturity, becoming somewhat plume-like. The seed heads turn light brown above the green foliage as they mature. Ribbongrass (Phalaris arundinacea var. picta) is a striped ornamental variety of reed canarygrass. It is also considered to pose a threat, both as an invasive species and by cross-breeding with established populations of reed canarygrass (see “Ornamental Grass Threatens Native Biodiversity”, WSU Extension Fact Sheet FS106E, for more information). SPECIAL INFORMATION: In WASHINGTON, reed canarygrass is designated as a Class ‘C’ noxious weed. Management may be required by law in your county. Consult your local Noxious Weed Control Board for more information.


Reed canarygrass is found in wet areas, along streams and ditches, in marshes, and along roadsides. It can be a particular problem along irrigation ditches and canals.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • None recommended

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • Applications should be made by those holding a current aquatic pest control license.
  • In Washington, a special permit is required for use of herbicides in aquatic sites.
  • Contact the Washington Department of Ecology or the Washington State Noxious Weed Control Board for more information.
  • Apply products to weeds when actively growing.
  • Spot treatments with certain post-emergent herbicides will control weedy grasses, but will also kill the turf.
  • Glyphosate products should be applied as spot treatments only!
  • NOTE: Some ingredients listed here are only available in combination.
  • Read the label carefully on combination products to make sure the product is suitable for your specific situation.

Landscape areas

  • glyphosate

Turf areas

  • No products approved for use in turf.

Bare ground areas

  • glyphosate

Additional Images