Cedar Flagging

Cedar flagging is a natural process that is often confused with a disease.  Evergreen plants, including conifers and broad leaf types, naturally shed some old foliage each year. Stress factors, such as insufficient water, hot winds, construction damage or other root disturbance, poor planting procedures, or recent planting can promote flagging.  It is being seen more often this year because it is more common when there is hot weather followed by cold weather.

Evergreens like Western redcedars shed old foliage every year. The symptoms of cedar flagging include the development of brown foliage on the tree or shrub in mid to late summer and this is very obvious by early fall.  Affected foliage is growth from previous years while foliage developed during the current year (new growth at branch tips) remains green.  The brown branchlets, called flags, are generally spread uniformly through the canopy.  During hot, dry weather, the foliage may drop.  Most of the dead foliage is blown or washed out of the plant by wind and rain in fall and winter and the tree typically looks healthy again by spring.

Management includes:

  • Additional irrigation may be needed during periods of summer drought.
  • Alleviate root disturbance from construction damage or other factors.
  • Correct poor planting practices when feasible. If affected plants were planted too deeply, it may be possible to replant them during the dormant season if they are not too large.
  • Check your local sewer drain pipe covers to keep them clear of this debris as the October rains begin to prevent flooding.


Hortsense: Cedar Flagging

PNW Handbook: Cedar (Cedrus spp) – Cedar Flagging

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