In late November 2020 I had some left over straw bales and some oyster mushroom spawn. We decided to try our hand at growing mushrooms on straw that had been cold sterilized with hardwood ash from our fireplace.
We set a hardwood ash bath for the straw at a 10% w/v concentration. The hardwood ash contains not only wood ash but also a lot of small bits of wood charcoal. We soaked the straw in the wood ash solution for 24 hours, periodically checking to make sure it was fully immersed.
After 24 hours we pulled the straw from the wood ash solution and placed it on some screen material to drain for 10 minutes. We placed a container under the screen to catch the solution drainage.
All of the drain and soaking wood ash water was poured into our compost bins. It will be at least 12 months before we plant into the soil below the compost bins. During that time, all the minerals from the wood ash will soak into the soil.
We layered straw/spawn/straw/spawn into a 14-gallon pre-cleaned plastic tote. We moved the plastic totes into our basement and loosely covered them with the tote lid.
We did see the oyster mushroom mycelium grow through the straw.
Then we waited and waited and waited for the mushrooms to appear. We have been rewarded for our patience, periodically, with flushes of mushrooms.
We found that our basement environment is not the optimal growth space for oyster mushrooms, because it is too cold. While this experiment didn’t yield the results we’d hoped, we learned some things and got the idea to use the spent straw mushroom substrate in another way.
Later this spring, we will be setting up outdoor grow beds under some trees for King Stropharia mushrooms. We will be using the oyster mushroom colonized straw, from our basement experiment, in the King Stropharia beds. Oyster mushrooms are primary decomposers with powerful enzyme systems. Oyster mushrooms prepare the growth substrate so that King Stropharia, which are secondary decomposers, can move in and enjoy the bounty.