Cold Shocking Mushroom Fruiting Blocks

Blue oyster mushroom

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In the exciting world of mushroom cultivation, we are often on the lookout for innovative techniques to maximize yields and make the process more effective. Today, we delve into a method known as “cold shocking,” primarily used to initiate fruiting in a wide variety of mushroom species. This tactic can stimulate your mushroom fruiting blocks to produce an abundant, healthy flush, and we will explore how and why it works in the context of mushroom cultivation.

What is Cold Shocking?

Cold shocking is a process wherein mycelium, the vegetative part of a fungus, is exposed to a sudden drop in temperature. This process mimics the natural environment for many mushroom species, especially those from temperate and cold regions. The sudden dip in temperature signals the mycelium that winter is coming, thereby triggering the fruiting process, which is the mushroom’s means of reproducing and ensuring the survival of its species.

Cold shocking is typically done by lowering the temperature of your mushroom fruiting blocks for a short period, typically 12 to 24 hours. This sudden temperature decrease helps trick the mycelium into thinking that it is time to produce fruiting bodies.

How to Cold Shock Your Mushroom Fruiting Blocks?

Cold shocking mushroom fruiting blocks

There are several ways to cold shock your fruiting blocks, but the common method involves the use of a refrigerator. Here’s a step-by-step guide:

  1. Prepare the Blocks: Once your substrate blocks are fully colonized by the mycelium and have consolidated well, they’re ready for the cold shock. Learn how to create your own fruiting blocks.
  2. Temperature Adjustment: Place your fruiting blocks in a refrigerator. The ideal temperature for a cold shock is generally between 2°C and 12°C (36°F – 54°F). This will largely depend on the type of mushroom species you’re cultivating. Remember, not every type of mushroom requires a cold shock, so do your research for your specific species.
  3. Timing: The duration for cold shocking also depends on the species, but it usually ranges from 12 to 24 hours. It’s important not to leave the blocks in the cold for too long, as it can hinder growth or even kill the mycelium.
  4. After the Shock: Once the cold shock period is over, remove the blocks from the refrigerator and place them in your fruiting chamber. Ensure your fruiting conditions (temperature, humidity, light, and fresh air exchange) are optimized for the species you are growing.
  5. Wait for the Magic: Over the next few days, you should see signs of primordia formation, which are the beginning stages of mushroom fruit bodies. These will eventually grow into mature mushrooms.

The Impact of Cold Shocking on Mushroom Fruiting

The main reason for cold shocking mushroom fruiting blocks is to stimulate the production of fruiting bodies. Certain mushroom species like Shiitake, Oyster, and various Psilocybe species, respond particularly well to this treatment.

By mimicking the natural life cycle of the mushrooms, the cold shock effectively ‘fools’ the mycelium into responding to what it perceives as an environmental shift, thereby initiating the reproductive stage. It can result in a more synchronized and sometimes increased yield, as all the mycelium responds to the cold shock collectively and fructifies at the same time.


Cold shocking is a powerful tool for mushroom cultivators looking to boost their yield and improve the quality of their produce. But remember, it’s not a one-size-fits-all approach; different mushroom species have different needs. Always research the specific requirements of the mushroom species you’re cultivating to ensure you’re giving them the best possible conditions for growth. Happy mushrooming!

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