Possible to mitigate aleopathic compounds in cedar?

Discussion in 'Pacific Northwest Native Plants' started by Ivar, Jul 21, 2021.

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  1. Ivar

    Ivar New Member

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    I'd love to have some pointers on how to diminish / mitigate / counteract the aleopathic substances in cedar. In my home garden I have a lot of cedar to dispose of. I'd like to use it in a hugelkultur but I've read that the chemicals in cedar that prevent many other plants from growing make that a bad idea. I'm hoping that perhaps someone knows of a way to get around this?
     
  2. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    You posted this in Pac NW Native Plants, so we can assume you're talking about Thuja plicata, Western Red Cedar?
     
  3. Ivar

    Ivar New Member

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    Correct - I'm referring to Western Red Cedar specifically, but if the aleopathic compounds are common among other trees I suppose any mitigation strategy would be relevant.
     
  4. Margot

    Margot Generous Contributor 10 Years

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    The following information comes from Dr. Linda Chalker-Scott from Washington State University and Dr. Jeff Gilliam from the University of Minnesota via a website called 'Dave's Garden'. Garden Myths Busted: Potassium / Magnesium+ Cold, Native Plants, Cedar Wood Chips - Dave's Garden

    The Myth

    Wood chips made from cedars will kill landscape plants.

    The Facts
    Many gardeners are reluctant to use cedar wood chips because they will kill plants. When one plant emits toxics that kill other plants this process is called allelopathy. One of the best known allelopathic plants is the Black Walnut tree. It is believed that plants do this to eliminate competition for water and nutrients.

    There is virtually no documented evidence for allelopathic activity in cedars.

    • It is unlikely that wood chip mulches containing cedar will have negative effects on established landscape plants.
    • The allelopathic activities attributed to mulches made from cedar and other species may actually be due to other factors such as nutrient and light limitations.
    • Seeds and seedlings, whether weeds or desirable species, are more sensitive to mulch suppression as they do not have established root systems.
    In closing, I expect some of you might disagree with some of these findings. However remember that this research was done in reputable university labs under controlled conditions. Each of us will draw our own conclusions.

    You can find lots of other articles by searching Dr. Linda Chalker-Scott - cedar allelopathy. https://s3.wp.wsu.edu/uploads/sites/403/2015/03/aleopathic-wood-chips.pdf

    When I lived in Burnaby, there were 4 enormous Thuja plicata on either side of our driveway which dropped incredible amounts of old leaves every year. Cars skidded trying to drive up the driveway and we needed snow shovels to clear it off. Believing that the stuff was allelopathic, I was meticulous about hauling it away to the municipal compost. Now I realize that the problem with it was more the volume than the toxicity. Many plants did grow well nearby unless they were smothered by the old leaves.

    It may be a good idea to let the old cedar leaves age for a year or so before using them for hugelkultur; I have no experience to say for sure.
     
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