Black walnut question

Asked July 18, 2019, 2:29 PM EDT

I have some Black Walnut bark that has been sitting for 2 years. Is it safe to use as mulch on paths of a vegetable garden that is all raised beds after this long a time?

Washtenaw County Michigan

1 Response

Hello,

If the bark was chipped and essentially left to compost, with weather hitting it, yes it is safe. You can test it by putting some around a single, separate plant, like a tomato plant, and see if there is any reaction over several days.

Here is a discussion, which indicates the juglone in mulched bark and wood disperses after 6 months of aging.

https://www.extension.iastate.edu/news/2005/jul/070701.htm

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