Growing Shiitake Mushrooms!

Blog post and photos by: Tara Laidlaw, Eagle Bluff Naturalist

Drilling holes in Ironwood logs.

As a California native, this early onset spring is making me feel right at home… but out here it’s keeping all of us on our toes! Yesterday morning I helped pull down the maple sap equipment after an unfortunately short running season, but in the afternoon I got a glimpse at a warmer-weather delicious-treat process: growing shiitake mushrooms.

Eagle Bluff became a Residential Environmental Learning Center about 15 years ago. Before that, it was the Forest Resource Center, an organization dedicated to helping landowners manage their forested land well. Part of the Center’s work focused on research about cultivating shiitake mushrooms, which take well to Southeast Minnesota’s climate without being invasive. Back in those days, the staff would inoculate up to 5000 logs a year for growing shiitakes. This year, we prepared 50… enough so everyone could give it a try, and that we’ll have enough mushrooms to share with visiting students in our fungus class and still have plenty left over for the dining hall to use.

When the naturalists arrived on the scene, two of the full-time staff members were ready for some extra hands. We started by clearing out from the growing area some of the old and thoroughly decomposed logs that had produced mushrooms last year,

Graduate Naturalist Colleen holding the mycelium-sawdust mixture that will inoculate the logs.

setting aside the ones that weren’t falling apart in our hands for another season of production. Then we moved the fresh ironwood logs, collected from the Eagle Bluff property, to the beginning of the inoculation assembly line.

The first step of the process is to drill holes all over the log with a power drill. The holes are about an inch deep and half an inch across; a small log will end up with 15-20 holes while a large log might have as many as 30.

Once the holes are drilled, the log gets rolled down the line to be inoculated. The mycelium – the stuff that will break down the log and grow into delicious mushrooms given the right conditions – arrives from the supplier mixed in with damp sawdust, allowing it to be picked up, packed together, and then, with a tap of the hand, pressed into the holes in the logs using a simple tool called an inoculator.

After all of the holes have been filled, they need to be sealed to ensure the spawn (that’s the mycelium-and-sawdust mixture) stays damp. We used melted wax, heated up in an old crock pot and maneuvered with a turkey baster, to achieve this.

Once the wax cooled and each log was checked for empty or unsealed holes, we moved the logs outside and stacked them up where they could soak in the approaching rain. Eventually, they’ll get moved into an enclosure that’s covered over with shading net, where they’ll stay as the fungus takes over the logs and produces delicious shiitake mushrooms for everyone to enjoy in about a year.

Naturalist Tony seals in the mycelium-sawdust mixture with wax.