Mushrooms Growing on Raised Garden Bed Logs

(Question)

Hi I am from Sudbury, Ontario and my father built me these raised garden beds from large 8×8 logs he had at home. We brought in gardening soil but now three years later i have these mushrooms growing on the wood. I did bring in sheep manure one year to supplement the soil. I’m not sure if they are edible or toxic. They somewhat resemble shiitake mushrooms but I have never planted any mushrooms here before. Any ideas?

(Answer)

Thank you for contacting Toronto Master Gardeners.

One of the main decomposers of logs in nature is fungi. The logs begin decomposing after the tree dies and slowly over time fungi spreads filaments, hyphae, through the logs and sends up mushrooms as its fruiting bodies. When you are walking in a forest you will notice most wood on the forest floor and some dying trees will have mushrooms and other large fungi on them.

For you to have mushrooms growing on your logs after three years is quite normal. Commercially, logs are used for propagating edible mushrooms. When used for this purpose they use new logs as they are not yet inoculated with the local fungi from their environment.

As a final note: unless you have a professional identify the mushrooms do not try them even if they resemble ones you normally eat and, always wash hands well after handling.

Further reading:

http://www.umoncton.ca/umce-foresterie/files/umce-foresterie/wf/wf/pdf/Mushroomguide.pdf

http://treesforlife.org.uk/forest/forest-ecology/decomposition-and-decay/