Grow Shiitake from Spawn

Preparing the Substrate

Use Black wood - Acacia melanoxylon or other broad leaved hardwoods, including - The Forest Alder, Iron Wood, and when you get your hands on Oak, you are guaranteed the best harvest. 

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 10 - 15% of the dry weight in wheat bran. Add 1% the dry weight in Calcium Sulfate (Plaster of Paris)  and molasses water - (25g to 50g molasses with 5L water). 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. You must remember, shiitake can take about 60 - 90 days to mature in the bags. 

I do not have the facilities to autoclave 100 bags at a time, so the result for my sterilization mostly comes from doing a 6 - 8 hour steaming 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 sterilizing, 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 4kg shiitake spawn bag with alcohol and then cut the top of the bag right across. I sterilize my gloves with alcohol and then gently fold over the plastic to create a bowl. Now spoon out a measure of shiitake spawn, to each receiving bag (10% - 150grams to 1.5kg 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. 

The Nursery

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.

shiitake mycelium

I visit my bags every day 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! Shiitake is a strong culture, and if small spot contaminants appear on the substrate, the bags are removed to my garden. I harvest one or two flushes, right in between my beans and lettuce. Get to the mushrooms before they open their caps or you may have insects to contend with.


shiitake ready

Remove the now browned logs from the plastic bags. Care for them daily, by giving them a quick mist spray, and inspecting the surface for any contamination. After the water spray the logs need to dry out again. Take care, not to over water in this phase. Once the logs have their browned barky exterior, I soak them for 2 hours, completely submerged in water, add a cap of bleach to the water as well. The logs are now removed from the water and placed in my grow room (Be careful, they can still break from the weight of the water it consumed), keep the humidity low for the first two days after the soak and make sure there are plenty of air flow. The exterior bark of the shiitake logs needs to dry off first, if kept wet at this time, you will get trichoderma infections (green mold), that may spoil big parts of your log. After the two days dry off time, you can start twice daily spraying your logs with a hand misting nozzle on your watering hose. Keep the room humidity above 80%, but allow it to drop to 70% daily. 3 - 7 days after soaking your logs you will start noticing the first pins forming. At this time, water the logs, but avoid spraying water on the caps, as this may spoil future produce. If your caps get cracks in, your humidity is too low in your room, and if you get brown spots or center black spots in the stems, you have too much water around your mushrooms.

pinning shiitake

Harvest, Dry and Soak

After harvesting a flush of mushroom, dry out the logs for 7 - 10 days before resoaking the them, and place them back in your grow room. You should get up to 5 flushes from each log.

Your shiitake mushroom is ready for harvest, having broken its veil, but not unrolled its entire cap yet. Shiitake are beautiful mushrooms, and besides the Ceps, my favorite for eating. 

Also Read: Cultivating Winter Oyster Mushrooms

With minimum effort, mushrooms can be successfully cultivated on logs outdoors.

You will need:

  • A High Speed Drill & 9mm Drill bit
  • some beeswax, cheese wax or soya wax
  • a Small gas burner and a pot to melt the wax
  • a paint brush to apply the wax
  • inoculated wooden plugs (Plug Spawn)
  • a wooden mallet

outdoor grown shiitake funguys smallThe best time to cut your logs is in Autumn or Spring. You can use Oak, Black wattle, Poplar and other broad leaved hard woods. Avoid Pine, Cypress, Yellowwood and other conifers and aromatic woods. Cut in sizes that are easy to manage - 1.2 m in length and between 12 and 25cm diameter. Let the logs rest for 3 weeks before inoculation. The bark is important protection for mushroom growth, as the mycelium can easily run between the heartwood and the bark.

  • Use colored tape to wrap around your drill bit to indicate the depth of your plug for drilling.
  • Drill a line of holes down the side of your log | 8 - 10 cm apart.
  • Drill another line of holes down the log 10cm away from the first line, but space the holes in such a way to form a diamond shape. Repeat drilling down the lines of holes to cover the entire log.
  • Use a rubber or wooden mallet to knock the spawn plugs into your pre-drilled holes.
  • Use a paintbrush to paint/cover the plugs with your choice melted wax as you go along.
  • Store the inoculated logs, off the ground, in a shady spot and cover with straw or hessian. (80% covering)

You can irrigate the logs, using a garden sprinkler for a couple of hours every couple of weeks. The logs can take anything from 6 months to 18 months before the first pinning of mushrooms. They will carry on producing for up to five years.

Once ready, stack the fruiting logs of the ground, two per level, piling upwards to a meter. Use bricks under the logs, to avoid the logs touching the ground. Some growers prefer to bury one side of a log into the ground and standing the verticle.

In the dryer hotter season, it will be advisable to irrigate the logs from time to time to add moisture.

For more detailed instructions, I found these 2 articles very usefull. Here and Here.


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