Shiitake mushrooms are one of the most widely consumed culinary mushrooms in the world. This is largely due to their distinct pleasant flavour which is used to provide many Asian dishes with an umami flavour. While readily available at most supermarkets in the dried variety, they can be hard to access as fresh mushroom in many parts of the world including the United states. This is unfortunate as many sources of dried mushrooms originate from China, where higher than acceptable levels of heavy metals ( eg lead) have been found in imported dried mushrooms ( the ideal levels are 0%). Luckily it is possible to grow your own shiitake mushrooms at home, providing you with safe and healthy source of nutritious mushrooms for much less than you would pay at the supermarket. While they can be more challenging to grow than common beginner varieties such as oyster mushrooms, with care they can be grown effectively and make for a rewarding challenge to new growers

Keys Facts

  • Shiitake mushrooms can be grown on hardwood logs or using a prepared substrate of hardwood sawdust- usually made using pellets such as these
  • Shiitake mushroom have a slow growing mycelium, taking approximately 12 mth to reach fruiting stage on logs, and anywhere from 7-12 weeks if using grow bags.
Fresh Shiitake mushrooms
Freshly picked shiitake mushrooms

Substrate

The ideal substrate for growing shiitake mushrooms is hardwood sawdust/ pellets. This closely mimics what the shiitake mushroom will grow on in nature – hardwood.
Shiitake mushrooms are one of the few hardwood loving species that does not prefer the Masters Mix substrate over a traditional sawdust block. Adding extra nutrition to the substrate can be achieved by the addition of wheat bran at a ratio of 10% wheat bran to hardwood pellets, however this may or may not produce improved results depending on the strain. It is consistently reported by growers that the addition of any material other than hardwood will lead to mutation of the fruits. While you can experiment by adding additional components to your substrate, nothing more than hardwood pellets and water would be recommended for your first grow.

Preparing a grow bag for shiitake mushrooms is relatively simple. Simply mix hardwood pellets with water at approximately 5 cups of pellets to 1.4 litres of water (for a large 5lb bag) and add to bags ( or mix directly in bags). Ensure they are not overly hydrated, if can pickup and handful of the substrate and squeeze it, a few drops of water should come out. If there’s a stream of water it’s over hydrated and you’ll need to add more pellets, and if no water comes out it’s under hydrated. Luckily hardwood pellets are already pasturised, therefore additional sterilisation or processing is not required, the bag can simply be inoculated and sealed. If you are adding other components such as soy Hulls or wheat germ you may need to sterilise the bags in an autoclave or pressure cooker at 15psi for 90-150mins.

Inoculation

Shiitake mushrooms are slow to colonise, and require a significant amount of spawn to be distributed between each of your grow bags. Adding a higher percentage of spawn ensure that the bags will colonise quickly, and provide extra nutrition to the mycelium from the grain spawn. Mushrooms such as oyster mushrooms can be inoculated at a ratio as high as 1 part spawn to 20 parts substrate , however for shiitake mushrooms this should be reduced to below 1 part spawn to 8 parts substrate. Its best to start with a higher ratio and work your way down to find what ratio provides you with the best yeilds, as this may vary based on your variety.

Colonisation

To colonise shiitake mushroom grow bags, simply place the grow bags in a room temperature environment without and direct sunlight for 3 weeks.

While the mycelium will initially appear white as it does with most species, the key sign that your mycelium is almost complete colonising your bag is a change in colour of large parts of the mycelium to brown. Additionally the mycelium will change texture to what is know as ‘popcorning’ due to the popcorn like appearance of the mycelium. This should begin to occur around 3 weeks to parts of your mycelium. Allow the bag to colonise a further 2 weeks from when the browning and popcorning occur.

To speed up and help the initial colonising process you can break up and shake the bag about every 7-10 days but stop once the popcorn appearance and browning is occurring.

Fruiting

After about 5 weeks from inoculation and when the mycelium has mostly turned brown, it is time to introduce fruiting conditions.

The first step of this process is cold exposure. Place you bags in a fridge at 3-5 degrees celcius for 12-2 hours. This will encourage your mycelium blocks to begin pinning as they try to fruit before the winter arrives. You will then need to place your blocks in a fruiting chamber at 95% RH and between 16- 20 degrees celcius. A shotgun fruiting chamber, tent, Martha, or tub chamber can be used. Allow the bag to rest in its fruiting chamber for 1 day before removing the block from its bag leaving all 6 sides exposed in the fruiting chamber, ensure the bottom of the block is not in direct contact with your water source. Pins should start to form within 5 days.

Harvesting

Harvesting Shiitake mushrooms can be a case of personal preference. Small mushrooms may have more depth of flavour while letting them grow large can result in greater yeilds. Remove them with a sharp knife to prevent harming your block between flushes. Luckily Shiitake mushrooms maintain there beautiful rich flavour well when dried, and make the perfect addition to soups and broths when dried. So don’t worry if you’ve grown too many to each with in a couple of weeks. Check out how to dry mushrooms here.

To harvest shiitake, take a sharp knife and cut the mushroom off at the stem, allowing it to fall into a basket, bowl, or other suitable container. Although shiitake mushrooms are pretty resistant to damage, it is still best to minimize the amount of handling.

Future Flushes

After a successful first flush it is recommended to your block out for between one and two weeks. To do this place your block back in its fruiting chamber without the humidity source for 1 – 2 weeks. After this rehydrate the block by submerging it in water for 24 hours. You may need to do this by obtaining a large tub filled with water, and a smaller tub to weigh down the block.

After this place your block back into your fruiting chamber and wait for your second/third flush (and fourth if you are very lucky . You can expect significant yeilss fr both your 2nd and 3rd flushes.

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