Cultivate Shiitake Mushrooms

cultivating shiitake mushrooms

A) Shiitake from Spore

If you purchased a spore print or a culture syringe to start your Shiitake (also known as Golden Oak Mushroom) cultivation, your next step would be to learn how to prepare AGAR media. Agar is a seaweed extract – a gelatinous substance that will solidify at room temperature. Sterilized by pressure cooking and is ideal food for mushroom cultures to thrive on. You will need a sterile space, a glove box or a laminar flow hood to do agar work.


See This Formula

Tinfoil and cotton Cap

Agar to Master Spawn

Once you have a culture growing on agar, transfer it to a sorghum and millet seed mixed substrate. I like to add millet seed, as it fills the little gaps between the sorghum seed, and Shiitake really like the millet seeds as well. You can start this by either using a  Glass JAR or a unicorn type bag with filter patch. I prefer the bags, as jars are a lot of extra work. When using a unicorn bag, fill it only with  or so of seed mix in the bottom of the bag, not too much. The seed mix is soaked for 12 hours, then dried again as to not feel wet to the touch. Sterilize the seed bag with seed (refer to sterilization), wait for it to cool, then in a sterile environment or a glove-box, inoculate the seed bag with your shiitake agar wedge. Leave the agar on top of the seed mix, where it drops. Gently close the bags, and place in a clean space, to incubate at 20 – 24 degrees Celsius. Let the mycelium grow out for about two weeks, and then give it a good shake, to disperse the fine growth of mycelium right throughout the seed bag. Place the bag back to incubate for another week. By now the mycelium would have consumed every last corner of the seed bag, and well on its way to becoming a white mass of master spawn. From here you can divide your master spawn again into 6 spawn bags, but now, you can use up to 3.5 kg of seed in each bag. Each 3.5 kg spawn bag can inoculate up to 30, 1.5 kg grow bags.

The Grow Bags

I use Gusseted filtered bags for growing Shiitake. Once filled to just under the filter patch, you can fit up to 2 kg of substrate per bag.

B) Shiitake from Spawn

Preparing the Substrate

Use Black Wood – Acacia melanoxylon,or other broad leaved hardwoods, including  the Forest Alder and Iron Wood, and if 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% of 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 with 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. Next I spoon out a measure of Shiitake spawn to each receiving bag (10% – 150 grams 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.

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, with a cap of bleach added 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 is 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 re-soaking 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.

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