Last week I popped over to the mushroom bed I had created at Middle Ruckham Farm a couple of months before to see how well the Elm Oyster mycelium was colonising the cardboard I had used as a substrate. On this particular occasion I was presented with the wonderful sight of little baby mushrooms (pins) poking out of the thin soil layer I had covered the cardboard with.
I will briefly explain the process I went through with photos to illustrate my explanations – If you want to try this yourself and would like to ask for some clearer instructions then comment or send a message through my Contact page.
Firstly I soaked some corrugated cardboard in living water from a stream on the farm (tap water can inhibit mycelial growth) and removed one of the flat sides to expose the corrugations. I then used a small 50g bag of Elm Oyster mycelium, growing on grains, sprinkled in between layers of the cardboard like a lasagna. This was left to incubate in a plastic storage container for a few weeks until mycelium was visibly colonising the cardboard layers. I added a little more water during this time to keep it moist, but not swimming in water, and covered the container with a towel to exclude the light.
When the myceliated cardboard was ready I picked a nice lightly shaded spot under a beech tree at the back of the garden area and cut back some vegetation to dig the bed for the cardboard to sit in.
Once the area was prepared and the shallow bed dug out I carefully separated the layers of cardboard and added fresh moist cardboard in between the colonised ones with a couple of fresh sheets in the bottom.
After I had sealed the top of the cardboard layers with a piece of fresh cardboard I added a thin layer of soil – removing larger woody matter – to cover over all the cardboard and kept an eye out for signs of mould or mycelial growth. If there was no rain for a week I would add some collected rainwater but otherwise it sat under the beech tree doing its thing.
Two months after creating this mushroom bed I noticed the first fruiting begin and in just three days the miniture mushrooms I first found (pictured at the start) became large fungal fruiting bodies ready to harvest and cook up with some butter, fresh thyme and homegrown garlic.
With Rosie’s culinary expertise these beautiful gleaming white mushrooms became a tasty little treat for a hungry bunch of WWOOFers and hosts…
The beds should produce more mushrooms from the cardboard and with the addition of some hardwood sawdust and/or woodchip a larger and higher yielding patch could potentially be created. The bag of spawn cost roughly £3-£4 (allowing for postage) and the cardboard boxes were ‘waste’. From small and simple beginnings there is the potential for many mushrooms to be harvested with very little effort or expense.
Interestingly the Elm Oyster has been shown to have a synergistic effect when grown beneath brassica plants by increasing the yield from the plants and providing edible mushrooms from space where nothing else would usually be grown. An experiment for next year perhaps?