Getting a Second Flush From Shiitake Blocks

One thing that makes growing mushrooms interesting is how well they give back to the cultivator. After a successful first flush on the same fruiting block, there's a high possibility that you'd get a second, third and fourth flush.

You get the best value of your work and biological efficiency by getting multiple flushes. Luckily, when kept in fruiting conditions, gourmet mushrooms like Oysters will naturally produce new flushes within a week or thereabout.

Shiitake doesn't follow this pattern. But you can also enjoy multiple flushes with shiitake if you employ some unique technique.

Strike and Cold Shock

Shitake is not like other gourmet species; growing it can be technical and may not be easy.

For starters, the blocks lakes longer to completely colonize to the point of fruit-bearing. The first inoculation may take about 5-7 weeks for shiitake to colonize.

After colonizing the block, you’d also have to hit it on all sides with your hands and also “cold shock" it.  You cold shock by putting in a fridge overnight. It helps the shiitake have a winter-like mood and put it into reproduction mode.

Resting Period

If you leave your fruiting blocks in the fruiting chamber after the first flush, it has a high tendency not to fruit again. Why? Well, unlike other gourmet, shiitake blocks need a resting period. During this period, the fruiting block is taken away from the fruiting condition and allowed to dry.

It's normal to think that the blocks will no longer be valid after drying out. It's quite the opposite as when the block dries out, it gets recharged during that period which prepares it for a second flush. In most cases, the flush used to be better than the first one.

The trick is to allow the block to dry out for a few weeks.  You can just leave them on a shelf or drying rack at room temperature. Ensure there is no room at all for moisture. Moisture can contaminate the surface of the block. Continuously turn the blocks day-by-day so that the drying can be even, especially if you are drying on a flat surface.

Once the blocks are dry, you should allow the block to sit for at least 3 weeks. There's no certainty on the time limit, so allowing the block to sit for a month or more could also work.


Re-hydration comes when you have dried the blocks entirely, and you've also allowed them to sit for a few weeks.

You do that by putting the blocks in a large tote or any container that can hold a large volume of water. Then you allow them to soak for at least a full day. Soak for 24 to 32 hours. If it goes beyond that, the blocks will disintegrate and no longer be applicable.

Place something heavy on top of the locks to keep them submerged. They can be a little annoying as the shiitake block naturally floats.

Subsequent Flushes

After the re-hydration, smack the block on all sides with your hand. Then arrange them back in the fruiting chamber.

You don't need a "cold shock" for subsequent fruiting; it could be counterproductive. Soaking the blocks in water is enough to shock, that is, if you soak them in cold water. This is good enough for second fruiting. 

When you arrange the blocks in the fruiting chamber, ensure the humidity is proper and that the blocks have access to enough fresh air. Even though shiitake doesn't require as much fresh air as oyster mushroom, it is essential to maintain high humidity.

You can re-run this process with the same blocks about 2 to 3 times before the blocks lose the ability to bear fruits or become contaminated. Usually, you will begin to notice tiny green mold forming on the sides of the blocks when they are in the fruiting chamber. When you see that, it's best to dispose of the block. You may want to resign to fate. You could place it out in the grass and see what fate does.

Multiple Flush Method For Shiitake

Step 1: Place on a shelf

After harvest, give the blocks space to breathe. Arrange them with good spacing on a shelf. Don't cluster them together.

Step 2: Dry evenly

Allow the blocks to dry evenly, watch them closely, and continuously rotate them probably on a day-to-day interval so that the drying can be even. That way, moisture will be eliminated, and you can avoid contamination that way.

Step 3: Rehydrate

Rehydrate blocks by soaking them in water. 24 to 32 hours is good. If it goes significantly longer, the blocks will disintegrate and lose their usability. Make sure they are firmly submerged as they tend to float.

Step 4: Fruit

You don't have to cold shock; just smack the block on all sides. Place them in a fruiting chamber under normal fruiting conditions. You can re-run the process with the same blocks 2 to 3 times.

Growing a Second Flush Outside

You can have a Shiitake patch in your garden using second flush blocks. It's pretty straightforward; after the first flush, give the blocks adequate resting time and soak well. You can then place them in the grass in your backyard.

The result cannot be the same as the one growing inside. The fruit will be darker but larger. Though in every likelihood, the yield will be smaller. On the plus side, you don't need to put in any effort; little care and attention are required.

You only have to just wait for the fruit to be ready, no monitoring, no watering whatsoever. It will take about a week or a little more for the tiny fruits to become visible, and in no time, you will have full-size mushrooms.

Because of sparse humidity, the fruits may blossom more on the sides of the block. Growing indoor will help you have an even distribution of humidity which accounts for better results. Regardless though it would be fun to grow outside, you may want to try it.

Getting More Out Of Your Shiitake

To get more out of your shiitake, you just need to follow the simple steps highlighted above. Yes, the life cycle of shiitake is a little longer, and compared to other mushrooms, the process may be a little complicated, but if you trust the process, you will get more out of your shiitake.

All information in this article has not been evaluated by the FDA in any way. Don't be mistaken; our products are not made for diagnosis, preventing, or treating ill-health. Consult with a physician; you should not take the information above as a direct replacement for proper consultation. Also, don't self-medicate using the statements from this article.


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