Preparing the Substrate
Use broad leaved hard wood shavings and sawdust – Acacia melanoxylon, oak, white pear, iron wood and many others.
The substrate used for growing your mushrooms is based on the following formula – a mix of wood shavings, sawdust and wood chip when available ( attempt to get broad leaved species of woods, for shiitake, oak is the best you can get), add 7.5% of the dry weight in wheat bran. Add 1% the dry weight in Calcium Sulphate (Plaster of Paris). The amount of water I use, will bring my substrate humidity to 60%; by no means does it feel wet to the touch, when you mix it; the substrate must feel damp, with no drops of water collecting on your hands at all. Too much water will invite anaerobic conditions, and soon you will see unwanted growth happening in the bottom of your bags and a sour smell.
Sterilisation is achieved from submerging my plastic bags for a 6 – 8 hour steam at 100 degrees Celsius at sea level pressure. To ensure this method works, you have to use a clean substrate. If the wood shavings at any time get wet, and or get clumped up and moist before you use it, rather use it as mulch in your garden. So I advise to use clean, dry wood shavings and sawdust; if you add wood chips, you can soak them for 6 hours before use.
After sterilising, I leave my bags in the steamer until cool, covered and safe. Once cooled, the bags are moved directly to my clean room. (You may want to use a room in your house that you have previously disinfected.) In front of my flow hood, I clean the entire working area with an alcohol wipe; have all my gear around me and ready. I clean my 3.5 kg spawn bag with alcohol and then cut the top of the bag right across, sterilize the gloves with alcohol and then gently fold over the plastic to create a bowl. Now spoon out a measure of spawn, to each receiving bag (10% – 150 g to 1.5 kg substrate). I like to give the bags a good shakedown after inoculation to disperse the seed downward and around the bag. It helps the mycelium to grow more balanced throughout the substrate.
Store your bags in a clean dark room until they are ready for fruiting. This could take up to ninety days depending on the strain you choose and under what conditions the bags are kept. The incubation room temperature is kept at 20 degrees Celsius.
I visit my bags every few days and they seem to appreciate the extra care. Try not to move them too much and keep a keen eye out for mycelial growth and contaminants. Separate any bags that appear in ill health and place them in hospital. I VERY RARELY throw away bags!