Fruiting Shiitake Mushrooms

Shiitake is a mushroom which has been cultivated on natural wood logs for thousands of years.

A more recent method is to pack sawdust into bags and mix it with the Shiitake spawn.

This enables people to really get into the ingredients of a shiitake log and figure out just what it likes!

Here at Oak and Spore Mushrooms, we have discovered a fantastic mix that grows some truly enormous Shiitake!

When Shiitake is colonised it needs to sit for an incubation period of between 40 to 100+ days in some cases.

The Mycelium will cover the man-made log in a thick white mat, then it will slowly start to form a brown crust

over the surface. When this brow crust nearly covers your log, it's ready to fruit!

Fruiting Shiitake shouldn't be a challenge, and I've found that with a bit of patience,

you can have more Shiitake than you know what to do with.

We will start this guide by assuming you have a fully colonised shiitake block that's nearly completely brown.

We want to separate the fruiting into four steps.

The first is birthing, which is where we prepare the block and unwrap it into the world.

The second is primordia formation, or 'pinning', the third is fruiting, and the fourth is a dunk and repeat
 


Step 1 - Birthing

Birthing is where we strip the Shiitake block out of its plastic wrap, and place it into a fruiting chamber or room.

Some shiitake blocks are happy to just have the plastic cut off and directly placed into the fruiting room,

but there are three good techniques we can employ to help them along. 
 

  1. Cold shock - If a shiitake block is subject to a rapid drop in temperature, it will often signal it to start bearing fruit.
    A cold shock can be done by simply placing the shiitake block in the fridge for a night or two.
    Make sure it
    doesn't freeze! After this it can be taken out, unwrapped, and placed into a fruiting room. 
     

  2. Shiitake Thump - Shiitake will often start fruiting if the block receives a thump or a jolt on the side.
    This can be done with a firm whack with your palm, but not so hard as to deform or crack the block - so be careful! Once you've given it a whack, you can place it into fruiting.
    Some say this simulates an infected dead tree falling over in the forest, telling the
    mycelium to start fruiting
     

  3. Water blast - Take your shiitake block outside and give it a good old squirt with a strong hose!
    Not so strong it rips the block apart, but if a few small flakes of brown bark fall off the side then that's ok.
    This can be repeated for a few days while the primordia is starting to form. 
    ​​

A combination of the above can all be used to help shiitake into the world, and ensure you are letting it know that it is ready to grow some mushrooms!


Step 2 - Primordia Formation

 

To form primordia, or 'pins' you need to provide the freshly birthed block with 4 things.

Light, humidity, fresh air exchange, and the correct temperature.

Light - Contrary to popular belief, mushrooms actually need a bit of light around the blue spectrum.
They like blue light because it scatters and gets to shady damp spots easier.
The same reason the sky looks blue to humans is because it scatters blue light.
You can use a cool blue fluorescent light, or just good old fashioned natural light! But don't leave it directly in the sun. 


Humidity - During primordia formation the shiitake blocks like it wet.
This is why spraying them with a hose during birthing can help with primordia formation.
It soaks the bark and helps create a barrier of very high humidity to try and encourage primordia formation.
Shiitake needs the humidity level above 90% for best results during primordia formation. 


Fresh Air Exchange (FAE) - Mushrooms love to create CO2, they are masters at it. If there is too much CO2,
they just won't fruit. To prevent this we need to ensure there is plenty of fresh air exchange around the shiitake block.

Ideally the air needs to be circulated and replaced 5-8 times per hour. 

Temperature - Shiitake generally like it cold. You can get warm weather strains,
but I believe they all like to pin at colder temperatures. Generally between 10 and 16 degrees celsius is perfect.
Too cold and they will slow right down. Too hot and their fruit is going to be of a sub-standard quality. 

 


Step 3 - Fruiting 

This is the part we have been waiting for.
All going well, you have provided your block with the perfect conditions and now have some good pins growing.
Now is the time to take them through adolescence into maturity.
At this time the humidity can be dropped back. 80% will do the trick, but it can be pulled back even further.
Donko Shiitake are known for their top quality and high price; these are caused by a huge decrease in humidity,
followed by an increase back to normal fruiting humidity. The temperature should remain between about 12-18 degrees. Try to keep the humidity and temperatures constant during this stage and the shiitake should form. 

 

I like to pick my shiitake right as the veils break away from the steam.
You can leave them longer but their shelf life degrades the longer they grow. 

Once picked, place the mushrooms in a 1 degree environment (i.e the fridge) as quickly as possible.

If stored correctly, your shiitakes can last 2 weeks!
 


Step 4 - Dunk and Repeat

 

Once you have cut all your mushrooms off the block, stick the block in a dry place and let it sit for a week or two. Following this, submerge the block in a bath of water (you might need to use a weight to hold it down).

After it has been in there for approximately 6-24 hours, remove it (you will know it is ready to be taken out when it has absorbed water and is heavier) and and put it back into the fruiting chamber.
All going well you will get another flush of shiitake!
This can be repeated numerous times, with reports of shiitake blocks that just keep on giving even up to a year
after they were first birthed! It is common to get 3-5 flushes.