Growing Mushrooms - Agaricus bisporus - Part 1

Growing Mushrooms - Agaricus bisporus

The idea of growing mushrooms has long been in the back of my mind but it wasn't until a conversation with Nick Vowles of Marshland Permaculture Interest Group that trigged me in to action. Nick said that he had trouble growing Agariucs Bisporus and this sounded like a challenge.

Agariucs Bisporus are the common mushrooms that are normally in the shops, Button Mushrooms.

A quick Google led to Mushroombox who sell the spawn and a short while reading up at various places on the net seemed to suggest growing them in horse manure would be ideal. Manure is something I have lots of so although other mediums may be suggested I have opted to try manure. 

There are a few conditions of my own that must be met, namely they mush grow outside, in a wooden box and rather than mix in straw I need to use hay, since again, I have hay.

Mushrooms, like anything, need the correct habitat to grow and so it is all about creating that habitat and where ever possible reducing the competition that they will face - no rocket science involved.  My main problem is going to be getting and keeping temperature and humidity right because they will be outdoors. In nature the conditions often aren't correct and to a large extent I will be at the mercy of nature. To help with this I have placed earth around three sides of my box to help keep the temperature more consistent and maybe I will add earth to the fourth side although I have place the box next to a path - a slight error in the location although I can move the path since it's just a matter of changing the direction of the lawn mower :)

The Box

Plywood base (yes it will rot) but if successful I can put in concrete slabs. This is just a first attempt after all. Pallet sides which are nice as they fit together. I'll make a lid at a later stage. 

Next is the manure. The manure has lots and lots of bacteria and other fungi as well as all sorts of other creepy crawlies in it and all of these will be competition for the Mushrooms so to help them the manure needs to be pasteurized.

Pasteurizing 4 or 5 wheel barrow loads of manure isn't easy but an old metal dustbin and a fire to heat it up seem the best way. Hard work and time consuming but easily doable.

I dug a small fire pit, about 18 inches square and about 8 inches deep and placed bricks around it and laid broken paving slaps either side so that the dustbin could be supported while still exposing the fire to the base of the dustbin.

Pasteurizing

Approximately two thirds of the dustbin was filled with semi rotted (4 month old) manure and a couple of gallons of water added. The water will steam and heat the manure better as well as keep the metal bin from burning and melting a hole in.

I had read that the Agariucs Bisporus is a secondary composter which simply means that the manure needs to have already been partly composted by other organisms before it gets to work. Semi rotted manure seemed to fit the bill.

What I hadn't given much thought to was the time it would take to heat up all of the manure. Four wheel barrows took most of the day. I don't know how hot the manure got but I considered ready was when the manure at the top was very hot to tough and steaming away. The dustbin lid was there to simply help contain the heat.

The result

A bit more manure went in after this photo so the box was about half full. A lid was placed over the box and the next stage awaits.

I haven't totally worked out the next stage yet but it will involve adding hay (sterilized) and the spawn, which should arrive today or tomorrow and perhaps some Gypsum. I now need to look at getting the balance between Carbon and Nitrogen right. I may not need to do any more because the manure has straw and wood shavings in which means there may well be a good balance already. 

I think the manure does already have the correct balance, or at least a good enough balance, for mushrooms since many wild mushrooms and fungi in general can be seen growing in various places around the garden as well as the rotting manure pile but the hay may also be needed to help get oxygen into the manure as well as act as a casing for the later stage.

Part 2 in a few days.