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June 24, 2022

How to grow Shiitake mushrooms

How to grow shiitake mushrooms. Everything you need to know to obtain a 10th dan shiitake blackbelt.

Want to learn about growing Shiitake mushrooms at home? This article will step you through the stages of growing a ready-made Shiitake block.

Are Shiitake mushrooms easy to grow?

They are fairly easy if you are using a pre-inoculated Shiitake grow kit. For our grow blocks, we have tried to make it as easy and fast as possible. If starting from scratch it can be challenging.

  • They are slow to grow. Compared to Oysters, they take about 4-6 months to mature and are ready for the actual mushrooms to start pinning (growing). Oyster mushrooms take about 3-4 weeks!
  • There are also several steps you may need to perform in order to will initiate fruiting. We’ve outlined these below in the section called creating the perfect autumn storm. 
  • Once growing the shiitake need little care, requiring less humidity and fresh air than Oysters.

We grow several different varieties of Shiitake, including the native Lentinula novae-zelandiae in addition to a Chinese strain which has dark caps, and a Japanese variety that has a lighter cap and very full fruit body.

Steps: How to grow Shiitake

We usually send the shiitake block in an advanced state of maturity. So, it will be close to growing.

However, it may be in one of the 4 different phases of late maturity.

  1. A completely white block
  2. Popcorning
  3. Turning brown
  4. Pinning
  1. White block: Leave the plastic on and wait for the white mycelium to start turning dark brown. However, if you see a very dark-looking dot or dots forming under the plastic, carefully cut a circle of plastic around the dot. If a mushroom forms after a couple of days, carefully take the rest of the plastic off. This is “pinning”. Proceed to the Autumn storm, but don’t slap in case you damage the mushrooms that may already be forming.
  2. Popcorning: The relatively smooth surface of the block may start to develop lumps. These lumps indicate the Shiitake is getting ready to pin. Proceeding to the “Autumn storm” should trigger pinning after a week or 2.
  3. Turning brown: Over time the white mycelium will start to turn brown. Eventually, the block will take on a dark patina, with the appearance of an old log with a cork-like texture. At this stage, you can take it out of the plastic and proceed to the autumn storm.
  4. Pinning: It will often look like, one of the lumps turning a very dark or darker brown, that slowly erupts into a baby mushroom. Note: pinning may start without the above stages completed, so could happen at any time. If this happens under the plastic, remove the covering immediately.

2. Create the perfect autumn storm!

When the bag is fully colonised, the following tips will help get the mushrooms growing (pinning). We call this process ‘creating an autumn storm’. You can do this to get a new block going. It will also kick a dormant block back into gear.

  1. Give the bag a firm but gentle slapping (a storm has blown the tree down!). Better to do this with the plastic on, or be gentle with it off.
  2. Cut off the plastic bag (giving fresh air …ahhh they just love that autumn breeze)
  3. Soak in cold water for a couple of hours (a passing rainstorm)
  4. Chill it down. Put it in the fridge for a couple of days (…winter is coming)
  5. Put it in a warmer spot and keep an eye on it (nice sunny autumn day, evaporating all that rain, …ahhh humidity)
  6.  …as soon as you see little mushrooms, mist the. Tap water is fine.

What’s the reason for slapping the shiitake block?

The shiitake can sense impact, which would usually be after the tree or branch has fallen during a storm. It is thought that this may be a signal to the Shiitake that it needs to propagate (grow mushrooms). This technique is used to initiate first pinning, but may also help if it has been dormant for a while.

Why should I put the shiitake block in the fridge?

In nature, the Shiitake grows in northern (cold) latitudes and will fruit in the autumn (and spring). It will detect the fluctuation of seasonal temperature. You would typically use the refrigerator, or an ice bath, if it hasn’t fruited in a couple of weeks, and the weather has been warm (say +23c).

Shiitake are very cold tolerant, often spending winter in a frozen log. Unfortunately, this means that many growers of Shiitake import frozen blocks from China and fruit them in NZ claiming that they are NZ-made. Our Shiitake is 100% NZ made, from NZ products.

Why and when should I soak the shiitake block?

Soaking the block simulates an autumn rainstorm. As far as the little Shiitake is concerned, it’s dreaming of being in a puddle on the forest floor. Together with raising the temperature a couple of days later, simulates a warm sunny autumn day. The shiitake sense this and know that the forest is now a perfect humid environment to grow.

You may need to soak the block at regular intervals. Half the weight of the shiitake block is water. So if a 5kg one is weighing in at 2.5kg… there is no water left. So if it’s getting close to 3kg it needs a soak. Tap water (with Chlorine etc) is fine.

The different stages of Shiitake mushroom growth

1. The White stage

After the block is made, the shiitake mycelium will slowly grow through the substrate. After about 6 weeks, the patches of white will thicken and slowly spread and eventually cover the surface of the entire block. After about 3 months it should appear thicker and have a velvety texture.

2. “Popcorning” stage

It’s easier to demonstrate this as visually. It looks almost like the Shiitake block is going through an exceedingly slow-motion boil. It’s typical that this stage happens before the browning stage, but it may happen after.

At this stage, some people may spray the white mycelium off using a high-pressure hose. This can speed up the browning.

2. The Browning stage

I find this the most wonderful stage. What we are seeing is the shiitake developing skin. Much like our own skin, this will protect it from the outside environment (from other fungi like yeasts or moulds, and bacteria). The skin is formed by liquid metabolites. You will see this under the plastic as a brown liquid. These metabolites are the Shiitake’s very potent immune system in action. These same metabolites are also in the mushrooms themselves when it grow. They are then bio-available to our own bodies, so we inherit them and boost our own immune system.

4. Pinning & mushroom growth

Eventually, some of the popcorning lumps will have a dark centre and grow into a baby shiitake. Once it starts to pin it requires less attention than Oyster mushrooms. As long as its in an area that’s not overly dry it should continue to grow. If it’s inside mist it several times a day, if outside you can just spray it with a hose.

Frequently asked questions

Here are some of the most frequent questions people ask about how to grow shiitake mushrooms at home. If there’s something missing please let us know using the live chat feature on our website.

What size shiitake block should I get?

The size will influence overall yield, but It’s hard to predict in kilograms, here is a rough guide

  • A 5kg block should produce about 2-3kg of mushrooms over its life. 
  • A 3kg block should produce about 1-1.5kg over its life. 

After receiving it, how long will it take shiitake mushrooms to grow?

Being nature and your own unique growing environment, it’s impossible to predict. Typically it takes about 18 weeks after we make it. This date is part of the batch number on the side of the bag. We then incubate it for about 12 weeks in our lab, so you still have several weeks to wait. However, the shiitake will respond well to your patience and general good vibes.

How long will the Shiitake block it last?

If you care for it, it should produce for over 12 months. If you are really good, closer to 24. However, it’s nature and there are a lot of variables that will affect its longevity. As it gets older its yield will decrease as nutrition is depleted. When you think it’s finally done, you can use it as mulch in the garden.

How often will the Shiitake block fruit?

It should cycle on and off fruiting every couple of weeks. Sometimes you may have the odd shroom popping up randomly, but if you have it in a good environment it should have a fairly consistent cycle, producing over a half-dozen mushrooms at a time. This is followed by several weeks of being dormant. If it has been dormant for over a month, try to initiate pinning by performing the autumn storm technique.

What’s different between your shiitake block and others?

We sell our shiitake blocks as mature, so they are generally ready to go. We have taken out the long wait and made success more certain. Others sell kits or logs. Kits may require you to find a suitable stump or log (usually a deciduous Harwood, like oak or Hickory, drill your own holes, seal with beeswax and wait… It may take over a year for anything to happen if anything happens at all. Some people want to manage and be part of the entire process, others just want to eat them.

Are these grown on logs? What are the mushrooms grown on?

We do not grow on logs because it’s a very slow process, and has a lower success rate. Instead, our Shiitake substrate recipe uses a combination of organic pine sawdust, plus some wheat bran for added nutrition plus water.

As the shiitake mycelium colonises the substrate it binds the loose sawdust into a fairly solid block and gains a texture similar to cork.

Where’s a good place to put the Shiitake block?

Shiitake require less care than Oyster mushrooms when it is fruiting. So it should be okay in any spot as long as it’s out of direct sunlight and drafts. They are more tolerant of being grown in sheds or garages, or outside in a shelter or damp location. However, beware of pests like mushroom gnats and slugs.

If you have an air conditioning/heat pump, be aware that this will dry the air. Please try and maintain a humid environment. Here’s an article about where to grow mushrooms

My mushroom caps are cracking!

This is considered a desirable quality especially if you are considering drying them for storage. This happens when the fruit body is moistened (misted etc) and you then let them dry out, as the cap grows. If you don’t want this happening then keep the cap moistened.

You can play around with the humidity and try to get the caps to split. Go for the perfect ‘hana donko’ grade shiitake. Or you can go minimal and simply watch them grow while you write your haiku.

When should I pick the mushrooms?

The perfect shiitake are picked soon after the cap separates from the stem, and starts to expose its gills. If you want a larger shiitake you can leave it a day or so to grow. If you leave it longer the cap will flatten out and drop spore. Try to avoid this. The Shiitake mushroom growing time is about 6-7 days.

What temperature does Shiitake need? 

Our general rule of thumb: If you are comfortable, they will be comfortable. But, Shiitake prefer running it a little cooler. They may go dormant in the summer months, so if you are wanting to increase production you will need to cool them by putting them in the fridge. The ideal shiitake mushroom growing temperature is between 12 and 18 degrees Celsius.

Some of my mushrooms are very small

Sometimes the fruit bodies will be small, but larger on the next flush. You may get smaller fruit bodies after soaking or when many are growing at the same time.

What if my Shiitake block dries out?

Shiitake are very hardy, and it’s likely that it’s okay. Soak it in water to rehydrate. It may bounce back quickly or may be dormant for a while. Be patient. Be careful not to oversoak it. This may damage the mycelium and encourage mould. The weight of the block, after soaking, should not be more than the original weight when you brought it.

If too dry the surface of the block may split or crack.

Do I need to keep it in the dark?

These types of mushrooms grow in the deep shade of the forest, so inside room lighting is about right. It doesn’t need light to grow, so it is equally ok in the dark. I prefer to give it a natural environment, as possible, to stimulate the production of micronutrients.

Can I put grow the Shiitake outside?

You can, but it’s likely that pests like fungus gnats will make a home of it and get to your mushrooms first. The larvae stage of the gnat lives inside the farm eating the mycelium and weakening it. They will eventually eat their way through the cap and fly away to lay more eggs. If you see little critters flying around your shiitake block, invest in some yellow sticky fly traps sold in garden centres.

Also, protect it from getting too wet, so rain etc as this may damage it.

I see mould, is that a problem?

Because we sell our Shiitake grow kits at a mature stage. There’s very little risk of a major mould outbreak. However, If the shiitake farm is too damp, after the soak, sometimes mould may appear. Often the shiitake can fight back and deal with it. If it’s struggling or looks like it’s getting worse, try dabbing some hydrogen peroxide on the mould. At worst, you may need to carve off the affected part out.

What if I over-soak it?

If you forgot and left it soaking for a few days, just let it drain and recover. It should be ok, but watch out for mould. The mycelium may have weakened so be careful in handling it. In extreme cases, the mycelium may have been permanently damaged and will quickly deteriorate and die.

I’ve grown your Oyster mushrooms, what’s the main difference with Shiitake?

Oyster mushrooms are very aggressive growers. It takes them 3 weeks (after making a bag) to fruit but the Shiitake needs 3 months. As a consequence, the oyster mini-farms are usually ’spent’ after 3 months whereas Shiitake can go 6+. Being aggressive the oysters will often have very large flushes or yields, whereas the Shiitake is less, but spread over a longer time.

Another main difference is that we remove the bag from the Shiitake but leave it on for the Oysters. This is because the Shiitake grows a protective skin, and the Oyster doesn’t.

They also require less humidity and care while the mushrooms are growing. The main challenge is getting them to fruit in the first place.

Why do you use plastic, is it biodegradable?

Unfortunately, we have not found a suitable substitute for the polyethene bags, but we are working on it. We are also very sceptical regarding the biodegradable nature of plastic alternatives (biodegradable plastics are almost an oxymoron).

If you cannot dispose of the plastic ethically please send it back to us. On the farm, we melt these plastics down into bricks that are used as edging etc in the garden. This way we can manage the waste by turning it into a somewhat solution. We are also acting as custodians of our waste until such time as it can be more effectively processed.

We are also in a good position and interested to experiment with strains of Oyster mushrooms that are being developed to digest plastic. Watch this space.

Further reading

How to grow Shiitake Mushrooms, the University of Vermont

Grow cycles guide how to grow shiitake

Buy a Shiitake Growing Kit

We sell our shiitake blocks as fully mature, so takes up to 4 months to prepare. Because they are very popular we are often sold out.

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