Elisabeth C. Miller Library logo Miller Library Home UW Botanic Gardens Home UW Botanic Gardens Home book graphic

3501 NE 41st Street, Seattle, WA 98195 | (206) 543 0415 | Open: | Library Schedule

Gardening Answers Knowledgebase


Knowledgebase record #556


PAL Question 

I have noticed that my old cedar has a very large number of cones on it this year. Several areas of foliage have turned reddish brown. This has all appeared in the past month or less. Some of the other cedars in this area appear to have these characteristics. Is something different going on this year? I am concerned that there may be a disease that is affecting them?

Answer 

Is your tree a true cedar (Cedrus) or a species of Thuja? The Thuja plicata (Western red cedar) in my garden also had a huge number of cones this year, and just like yours, it has some foliage turning reddish brown. This is probably cedar flagging, as described in this Washington State University Extension page. Flagging--the browning of older leaves and twigs--is a common occurrence on western red-cedar and related trees, such as arborvitae. It usually develops in late summer to early fall. Often, very hot, dry weather, followed by rain, will stimulate the sudden dropping of this older foliage.

If the browning were to be widespread, that might be more of a cause for concern. Additional links:

Cedar Flagging from Private Forest Landowners in British Columbia

Keywords Thuja plicata, Trees--Diseases and pests--Washington
Season All Season
Date 2007-10-10


Need an answer to your gardening question? Ask us directly!

Browse keywords or Search:

Keyword Search