Growing Mushrooms Using A Casing Layer

It was discovered by some mushroom farmers that putting a layer of soil on top of a planted mushroom enhances its growth. Hence, the layer of soil placed on the planted mushrooms is known as the casing layer.

This procedure was recently discovered as one of the most effective ways to grow mushrooms. This article will reveal to you the benefits and the do-it-yourself procedures.


Knowing what the casing layer is all about will help you understand and give a clue about everything it's used for. So, what's the casing layer?

The casing layer is simply a layer of wet soil put on top of a substrate in which the mushrooms grow before it starts to shoot out.


The casing layer is beneficial for growing mushrooms. Without a doubt, it enhances mushrooms' productivity and increases their yield. A well-balanced humid environment is needed to enjoy all these benefits because moist soil is needed for the covering, and the soil must remain moist.

However, any alteration to the integrity of this moist soil will cause damage to the mushrooms. This means an increase in the soil temperature will cause the mushrooms to gradually dry. And this, in turn, will also affect the fruiting of the mushroom. Hence, these mushrooms won't be as productive as they should be without any alteration.  

Additionally, humid surroundings are needed for maximum productivity and effectiveness of the casing layer. This helps the mushrooms when planted in environments with high temperatures. Thus, constant application of water is needed to be required to maintain the humidity. Either of these is used to keep the casing layer humid; sparing bottles, watery cans, or knapsack sprayers are implemented.

Materials Needed For Casing Layers For Home Growers.

There are many materials used for casing layer procedures; these include garden soil, sphagnum moss, coco coir, et cetera. Tho, peat moss and vermiculite are used primarily due to their availability, water retention capacity, and to withstand contamination.

However, making a casing layer for king oyster blocks requires knowing the best layer, peat moss, and vermiculite. Yes, the best and the most recommended casing layer is the addition of peat moss and vermiculite with a 50:50 ratio, mixed to field limit, and about 30-40minutes of sterilization.

Furthermore, the materials needed for making king oyster blocks are; a large bowl, polypropylene bag; large pot; temperature probe; vermiculite, peat moss. Also, below are the step-by-step procedures needed for making king Oyster blocks;

  • Mixing of Ingredients

Peat moss and vermiculite should be put together in a large bowl in a ratio of 50:50.

After which, you thoroughly mixed with water until it attained the best moisture level. What is the best moisture level? This is when you squeeze the content and only a tiny water drops.

  • Pasteurization

There is every possibility that casing layer that the casing layer will have been contaminated. So, some actions need to be taken to save it from spoilage.

And this action is known as "Pasteurization ."Which is a partially heating procedure that eliminates contaminants. How? You can pasteurize by doing the following;

To pasteurize these mixtures, peat moss, and vermiculite. You need to put them in an air-tight bag and allow them to boil for some minutes (30-40minutes). Hence, when the mixture reaches the pasteurization temperature of 65-80°C, you are sure your mixture is free from contaminants.

  • Cool And Apply

There is a need to remove the mixture from the heat and allow it to cool before applying it to the substrate. Also, for substrate application, you can either use your bare hands or nitrile hand glove. Just make sure you thoroughly wash your hands after application.   

  • Place In Fruiting Chamber And Wait

After the casing application, the block of the casing has to be placed on the fruiting chamber. And between 4-7days, the mushrooms will shoot out through the casing. Hence, Normal temperature has to be maintained to avoid the casing layer from drying out.

  • Harvesting

This is the last and most crucial step because you need to be careful at this point, or else there won't be continuous growth. Harvesting in the wrong way or tampering with the slabs can alter the growth of the mushroom. So, when harvesting, you can use your hands or a sharp knife or saw; just be careful not to tamper with it.

This is where the mushrooms are matured, and harvesting it is the only way to enjoy it. You need to be careful because When the mushrooms have grown to a reasonable size, you cut the mushrooms from the bottom of the stem, and you have it.

After harvesting, there are two options you can adopt; one of the options is to continue the growth process. All you need to do is put the fruiting block right inside the chamber, and after 4-5 days, it will start to shoot out.

And the second process involves the removal of the previous casing and re-applying the new casing, and the fruiting will begin in 7 days.

Other Mushrooms That Benefit From A Casing Layer.

Without a doubt, not every mushroom species will grow or benefit from the casing layer cultivating process. One of the mushrooms that benefits from it is the Reishi mushroom. This glossy woody mushroom benefits significantly from the casing layer.

Also, some mushrooms won't develop in the absence of a casing layer because they depend on certain microorganisms, namely bacteria and molds, to fruit. This mushroom includes Button mushroom, Shaggi mane, King Stropharia, et cetera. When processing the species above, pasteurization must be avoided.

Cons Of Using Casing Layer.

Regardless of how beneficial this procedure is, it comes with its disadvantages which are highlighted below:

  • The developmental stage requires more time and energy.
  • For a casing layer to be successful, much fresh air is required. Hence, where there is less fresh air, the casing layer can easily be polluted.
  • It is easily destroyed if the environment remains wet after pollution.

Additives For Casing Layers

Due to the acidic nature of peat moss, the addition of calcium carbonate is needed in the mixture to aid the Ph. And this will certainly prevent it from contamination.

Furthermore, some mushroom farmers have found out that using hydrated lime (calcium hydroxide) helps in improving the work of the casing. Also, farmers don't need to use either calcium carbonate or calcium hydroxide, especially if the grower wants to grow the mushroom more than once.


The casing layer has been proven to enhance mushrooms' growth, and it was also discovered that some mushrooms can't survive without a casing layer. You need to sterilize your casing layer to avoid contamination, but not every mushroom species should be pasteurized to attain maximum yield.

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