OK, not the greatest picture - but man was it a tasty mushroom!
Growing Shiitake on Oak Logs
I've confessed before that I am a little obsessed with mushrooms - from growing oyster mushrooms in coffee grounds, to learning about edible wild mushrooms. (I'm still too nervous to eat them though!) Yesterday I finally got a reward for one of my more long term mushroom projects - growing shitake on oak logs. It's way easier than you might think.
Last Spring I contacted a local tree surgeon and scored a truck load of oak logs that had been cut down from a neighbor's yard - you need to let them sit for 3 weeks or so to allow the natural fungicides in the live tree to die back. In the meantime I ordered shiitake, oyster and lion's mane plug spawn from Fungi Perfecti - whose founder, Paul Stamets, gave a fascinating TED talk about how mushrooms can help save the earth. Then it was simply a case of drilling holes in the logs, hammering in the oak dowels (which are inoculated with spawn), and then covering the holes with wax.
Updated: Here's a step-by-step pictorial of the process courtesy of furtwangl on Flickr. (Note that they are using sawdust spawn, not oak dowels, but the process is essentially the same.
Step One: Drill the Holes
Step Two: Insert Spawn
Step Three: Wax Over Holes
Step Four: There is no step four....
Once the logs are inoculated, you simply let them sit - preferably in a damp spot, raised off the ground so that they don't become colonized by other mushrooms - and you wait for them do their thing. The process can take anywhere between six months and two years. All you need to do is to water them every few weeks if the weather is dry.
My mushroom logs stacked behind the barn.
Eventually, usually in the Spring or the Fall, the logs will start fruiting - you can tell they are about to burst forth when you see a dark mottling on the cut ends of the logs. Often fruitings will occur after a few days of heavy rain. Alternatively, you can try shocking the fungi into fruiting - this involves submerging the logs in cold water for 24 hours, and then bashing the log with a mallet or dropping it on a rock. Nobody is quite sure why this induces a flush of fruiting - but it may have something to do with fungi suspecting that a tree nearby has fallen, and hence sensing that it's a prime time to spread its spores. We've yet to have any luck shocking our logs - but I do have one sitting in the creek behind my house (pictured below). Once I drag it out and bash it, I'll post if I see results.
Soaking this log in the creek will hopefully induce fruiting
Of course, as with all things green there are gray areas around converting trees into food - after all, I'm really taking sequestered carbon and releasing it back into the atmosphere. I tend to take the view that as long as I am using waste wood that would otherwise be decomposed or burned, then that carbon is being released cleanly, and with a side product of nutritious, edible mushrooms - and whatever is left of the logs becomes valuable compost for the garden.
Update: Here's a video from the Urban Farming Guys on how they do mushroom log cultivation: