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Category: Mushroom Growing Guide

Rehydration of psilocybe cakes

Mushroom cake soaking. Mushroom block soaking
Mushroom cake rehydration to trigger new flush of fruiting

STEP 14. Day 32-33. How to soak magic mushroom cake in water and initiate new flush of fruiting

During the first flush and after harvesting you can see the mushroom cake is shrunk. Each container has from 1/2 inch to 2 inch gap from the sides of the tub. But they were flush at the beginning. What's going on?

Mushrooms absorb water from your cake. A lot of moisture evaporate from the top layer. Hence, mushroom cake/block lost moisture and shrunk. Rehydration (aka soaking in water or spraying water on the top layer) makes up for the loss of moisture. It works for mushrooms as a trigger for fruiting in the same way as rain in nature

Why magic mushroom cakes need rehydration

  1. As you know, mushrooms consist of 90-95% water. During colonisation period (in incubator) and fruiting period (in fruiting chamber) mushroom substrate loses moisture that is so important for development mushroom bodies. No moisture - no shrooms.
  2. Spawn and Bulk substrate can be dry. Therefore some growers practice rehydration even before the first flush in case top layer isn't wet enough (improper field capacity, high evaporation rate, if colonisation period lasts more than 3 weeks).
  3. To start new phase of fruiting we need to simulate a long rain for our mushrooms. Every mushroom hunter knows - the best time to set out to look for mushrooms - after a good rain. If nature already has everything in place and in right order, then in our simulated conditions we still have to work hard. The main purpose of rehydration is moisture compensation wasted by the mycelium. You need to fill all cakes with water, so that mushrooms really begin to grow like after rain. Rehydration stimulates new flush of fruiting, helps to harvest more mushrooms and more weight of shrooms.
  4. Rehydration helps to wash out waste products of mycelium metabolism such as acids and waste enzymes;
  5. Rehydration promotes nutrients and beneficial enzymes for further mushrooms growth.

When do we need to soak mushroom cake?

  1. Before the first flush, if your cake is totally dry. Recommended for PF-tek cakes after colonization and small mushroom cakes if colonization lasts 2 weeks and more.
  2. After the first flush of harvesting is must have for any tek of cultivation: pf-tek, small mushroom cakes, bottle-tek, shoeboxes, monotub.
  3. Repeat rehydration after each harvesting to initiate new flush of fruiting.

Prepare mushroom cake for dunking in water

Remove all mushrooms (even the smallest ones) and their stumps from the cakes. Mushroom cake should be completely bald.

Magic mushroom cake preparation for rehydration
Mushroom cake preparation for rehydration (Brazil)

If you have dry crust of overlay on the cake, scrap it with sterile fork. It helps to provide access of air and water for further mushrooms development. Cake won't absorb water through the overlay! Details: Overlay & Stroma

Check your cakes from all sides. If you take the cake out of the box you can find some mushrooms on the sides. Pick them also.

Cultivation magic mushrooms. PF Tek guide. Mushroom cake preparation for rehydrating
Mushroom cake preparation for rehydrating

Rinse each cake thoroughly under the running water.

Rinse mushroom cake under running water before rehydration
Rinse mushroom cake under running water before rehydration

Put the cake back in the plastic container (wash this container before). You put the cake in a bigger plastic box, it is more convenient.

Psilocybin mushroom cake ready for rehydrating
Magic mushroom cake ready for rehydrating

How to soak mushroom cake in water

For soaking mushroom cake you can use just tap water. Clean drinking water is also great!

Fill each box with water. Rehydration process for magic mushroom cake
Dunking magic mushroom cake

Pour water over the cake.

Growing Psilocybe Cubensis mushrooms at home. Rehydration technique. Pour water with honey (or sugar) over the cake
Soaking mushroom cake. Pour water over the cake

Cakes are lightweight. When you fill them with water they will float. You have to submerge each cake completely in water! Put something on top of the cake. This can be any jar or glass of water. Repeat it with each mushroom cake.

Submerge magic mushroom cake completely in water
Submerge psilocybin cake completely in water. Put smth on the top to press the cake

Leave mushroom cakes for soaking in water for 3-4 hours at room temperature.

Leave psilocybe cubensis cake for soaking (12-24 hours) at room temperature
Leave mushroom cake for soaking

Less attractive, but handy option to use larger containers for soaking cakes. Fill them with water, add cake and put a weight or a lid on top

Rehydration mushroom cake in bigger containers
Rehydration mushroom cake in bigger containers

Some growers provide cold shock for cakes at this stage. They soak cakes in the refrigerator or add ice in water. This step is optional. Personally, I add ice occasionally, not always

After 3-4 hours of soaking drain the water from the container. Take cake out of the container. Rinse each cake thoroughly under running water once again.

Rinse magic mushroom cake after rehydration under running water
Rinse mushroom cake after rehydration under running water

Don't put the cake back into the plastic container. Put it on the upside down container as a podium to allow mushrooms to grow from the sides. In such way cakes won't contact directly with water in growbox. Also it will be convenient to take them out for cropping.

Wash your fruiting chamber thoroughly before placing mushroom cakes for the new flush of fruiting.

Pour one glass of water in your growbox tub (Optional! You can add 5-10 ml of H2O2 hydrogen peroxide solution 3% in water) and put mushroom cakes inside.

Psilocybin mushroom cakes in growbox after rehydration
Psilocybe cubensis cakes in growing box after rehydration

Dunking mushroom cake in honey water

Honey water recipe for dunking mushroom cake
Honey water recipe for soaking mushroom cake

I will say right away that such method has advantages and disadvantages!

Honey water recipe for soaking mushroom cake

Add only 1 teaspoon of honey per 1 Quart (1 liter) of clean water. Stir thoroughly!

Honey water for soaking mushroom cake
Honey water for dunking mushroom cake

Prepare as much as you need for dunking your cakes. Pour honey water over cake.

Growing Psilocybe Cubensis mushrooms at home. Rehydration technique. Pour water with honey (or sugar) over the cake
Rehydration process. Pour water over the cake

Flush by flush mushroom cake loses nutrition resources. That's why honey water can be as additional support for mycelium and further fruiting, especially on the last flushes. As a result we can prolong fruiting period.

Benefits of soaking mushroom cake in honey water (or corn syrup, dextrose, malt extract) based on a few practical experiments.

However you can face with another issue. Bacteria/yeast love all types of sugars (carbohydrates) and you can provoke bacterial/yeast contamination. Although I didn't have contamination in my own experiments, but it's great potential to have them.

Moreover, mushroom metabolism can be 'confused', because mycelium need time for adaptation to another type of carbs (from substrate carbs to honey carbs, that have some differences). As it takes time, bacteria/yeast can use this moment.

Mycelium 'memory' works better if you inoculate jars with liquid culture based on honey/corn syrup or used drippy corn tek, so that mycelium can match previous early experience for metabolism.

All of the listed above are just my observations!

Please, share your thoughts, experience and scientific arguments regarding adding carbs (honey, LME, dextrose etc.) for soaking in comments to this article.

Soaking mushroom cake in alkaline water

Flush by flush mushroom cake is gradually acidified by mushroom waste products. Acid substrate (lower than 7.0) is extremely vulnerable for green mold contamination aka Trichoderma.

pH scale
pH scale

Most of molds, including Trichoderma green mold, prefer acidic soils pH 4-6. After the first flush substrate pH can change gradually from 7.5 from the very beginning to 5.0-6.5 after the first flush

That's why the risks to catch green monster is higher with the next flushes, when pH drop from 7.5-8.0 to 6.5 and lower

🔴 Recommended: How soil pH affect Trichoderma

One of the methods to reboot pH level for mushrooms is rehydration in alkaline water pH 8.5 - 9.5 and adding new layer of pH adjusted casing (about 0,5 cm) after rehydration to protect mycelium.

By rehydrating the mushroom cake with pH adjusted water the pH back up to a level that is hostile for Trichoderma, but allows mycelium to thrive and produce fruits again. Although sudden changes in pH can damage the beneficial bacterial colonies in substrate!

How to prepare pH adjusted water for soaking mushroom cake

Your local tap water may be naturally hard and alkaline (containing calcium, magnesium, carbonate), which adds further to the higher pH (7.2-7.8). Tap water may be acidic (5.0-6.5). Distilled water has a neutral pH 7.0.

If you want to increase the pH of water use:

1 gallon (~4L) of water (tap or distilled)

1/8 to 1/4 tea spoon of hydrated lime (aka Calcium Hydroxide Ca(OH)2, Slaked Lime or Pickling Lime).

Pure Calcium Hydroxide (Slaked Lime) 50g/2oz $7.99

Laboratory-Grade Calcium Hydroxide 500g $22.49

Shake it thoroughly and leave it for 12 hours.

Check the pH level. It should be around 9.0. If lower add just a pinch of hydrated lime, shake it well and leave for an hour before measuring pH level again.

pH 10 and higher can be harmful for mycelium metabolism, also harmful for beneficial bacteria in substrate.

Baking soda not allowed for fungi!

How to check water pH

Test the pH of your water with pH test strips or pH meter:

pH Test Paper 1 to 14 for water, soil, body $6.55

pH Test Strips 0 to 14 for Water & Liquids $11.97

Digital PH Tester for water $12.99

How to make rehydration for mushroom cake in MonoTub or Shoebox or Bottle-Tek

Don't remove mushroom cake. Wash and pour cold water (or pH'd water) right in the plastic tub, shoebox or bottle.

How long to soak mushroom cake when rehydrating after a flush

It is debated topic. Let me share different options.

Newbie growers rehydrate cake overnight (for 8-12 hours). It's relatively fine, however it doesn't take that long. Prolonged soaking can cause fermentation issues. Although, I never had it, when I ran experiment with 8-12 hours of soaking shroom cakes.

Some growers hold mushroom cake under cold water with added ice only for 10-30 minutes. It is considered that mushroom cake like a sponge absorb water in the first minutes, it cannot absorb more and long soaking is not required.

There is also a common rule among mushroom growers: 1 hour per inch of substrate for full soak immersion.

Based on my experience, I'd suggest dunking cake for 3-4 hours. More than enough. Right or wrong, but this timing always works great for my small and big cakes!

Maintain proper fruiting conditions and wait for the new flush. Ready!

Can I skip dunking mushroom cake and mist the surface instead

Question: Hey, Shroomok! I usually avoid dunking (I see that as a high risk for contamination) and instead I just mist the surface until it's really well soaked.

Usually I dunk cake if the top layer is dry (always do this after the 1st flush, when cake really looses a lot of moisture).After the next flushes I act case by case. If cake wet enough I just mist the top layer. If cake produced huge rich flush, then I soak it again. Sometimes good misting or spraying water on the top layer till small puddles appeared is enough to trigger the new flush of fruiting. However full rehydration (soaking in water) has more benefits than risks!

Full rehydration helps to wash out waste products of mycelium metabolism such as acids and waste enzymes. Rehydration promotes nutrients and beneficial enzymes for further mushrooms development. That's why I'd suggest full rehydration at least every other flush.

Avoid water pools on top layer AFTER rehydration, whether it was soaking in water or just misting. Water pools should disappear (absorbed/dried out) within the next ~8-12 hours after soaking or misting!

How to rehydrate Panaeolus aka Copelandia mushroom cake

Don't soak in water Panaeolus (aka Copelandia) mushroom cake if the main substrate is manure. If you soak such cake in water it loses the shape and turns into mud.

For Panaeolus rehydration just spray water on the top casing layer till small puddles appeared. Maintain proper fruiting conditions for Copelandia and wait for the new flush.

What if mushroom cake has strange smell during or after soaking

If you feel a smell of something fermented, rotted, cider, vinegary, sweet and sour, stale, yeasty, smell of dirty socks, alcohol — all these are clear signs of fermentation (bacteria/yeast contamination). It is a common issue if you had mild bacteria contamination in grain spawn before making mushroom cake/block. High temperature and water speed up fermentation process.

Fermentation — the state of actively growing microorganisms, usually in a liquid environment. Smell is a good indicator of fermentation, it starts out with a sweet vinegary odor and then turns to a denatured alcohol smell. Fermentation in cultivation is a sign of contamination. The bacteria are breaking down the yeast and causing the fermentation of the tissue

🔴 Recommended: Mycology Glossary & Abbreviations

Mild smell is not a problem. To prevent such fermentation process add 10-20ml H2O2 hydrogen peroxide solution (3%) per 1 Quart (1 liter) of water. Shake it well and use for soaking mushroom cake no more than 3-4 hours. But if your cake totally healthy don't use H2O2, because it inhibits useful microorganisms and mycelium as well. If you notice visible signs of contamination i.g. slime, rotted areas and strong smell, then toss mushroom cake or bury it in the garden!

🔴 Recommended: Wasted mushroom cake: carry on or throw away

Fruiting conditions after dunking Cubensis mushroom cake

  • Temperature +20°..+25°C or 68-77°F
  • Relative humidity 90-92% (possible range 85%-95%)
  • Light 12 hours on/off cycle - optional
  • Fresh air exchange 2-4 times a day for 2-3 minutes. Or turn on air pump 24/7. Or turn on PC fan for 1-2 minutes every 2-4 hours. Or just natural air flow through air vents in your fruiting chamber.

The next flush are going to develop faster. In 2-7 (up to 14) days you'll see new pins and mushroom bodies on the cakes. In 7-14 days it's time for harvesting.

Now looking forward for the next flush of fruiting Psilocybe Cubensis mushrooms!

Move on — Step 15. Day 38-41. Second flush of fruiting and harvesting Psilocybe Cubensis


Wonderful guide! Thank you! I am going to experiment with adding some honey when I rehydrate my substrate. I am also thinking of adding some soil as a casing. I figure it does not have to be sterilized because the mycelium is well established.

Question, have you had much luck growing any mushrooms in your garden?

Shroomok avatar Shroomok

@VK each method has pros & cons. Play with different options to find the best tek for you. Don't forget to share your results, please ;)

Casing isn't nutritious, so sterilization isn't necessary. We use pausterization (steam heat or in the oven for 1-2 hours at 160-180F or even in microwave). But the main point for casing is pH adjusting. You can find details on Step 8. Casing section

Regarding outdoor growing, yes you can bury wasted cakes in the garden in the shade and get shrooms. It is possible under proper climate conditions (warm, high relative humidity), because P. Cubensis are warm-loving tropical/subtropical shrooms. Check the examples I've shared on the final Step 20: Disposing of shroom cakes

Psilocybe Natalensis (African species) great for indoor and outdoor growing for hot season (77-105°F or +25°..40°C).
Psilocybe Azurescens is possible to grow on an outdoor bed in continental climate.
You can cultivate some edible mushrooms outdoor as well ;)


The instructions above for soaking period required or recommended for rehydration are all over the place. Seems to range from 20-30 mins to 24 hours. In one case, a picture and the caption had wildly different times listed.
This should be corrected.

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