Casing for Dummies
By Hongus

Nan's Nook : Archives : Casings : Casing Teks


So now you have fully colonized jars waiting to fruit. You can now choose many methods to get them to fruit. You can fruit them as cakes or casings, but since this is called "Casing for Dummies", we are going to discuss a very simple casing method that will make a pro out of you and will also improve your yields dramatically.

A casing is simply a "shell" that provides moisture for the substrate. There are many types of casing materials, but we are going to use vermiculite. Vermiculite is a soil conditioner that retains water. It does not contain nutritional value in itself, so it will help ward-off contaminants.

Mushrooms are about 90% water. They use moisture from the air and the media in which they are growing to fulfill their water needs. This is where the casing plays it part.

You have to decide how many cakes are you planning to case. You can create nice, one-cake casings, and you can create humongous four-cakes casings. The more you case within a tray, the more plentiful the flush. This is because the mycelium network is stronger. There is the risk that if the casing gets contaminated, well´┐Ż you lose all the cakes invested in it. Not with one-cake casings. If they show contamination, you just dispose of that particular one, not four. I would recommend you to experiment with smaller two-cake casings as a compromise between both ends. After getting a hold of the concept, experiment until you find something that suits your needs.

This is what you need to do a plain vermiculite casing:

  • A bag of vermiculite. Available at many garden centers and stores
  • A gallon of distilled or spring water. Available almost everywhere except in some deserts.
  • A tray or container with a lid (or plastic wrap) that will hold the casing.
  • A bowl to mix-in the vermiculite and the water.
  • A spoon.
  • Lysol® (antibacterial disinfectant spray)
  • And the cakes to be cased.

As a side note regarding the tray, try to get one that is not see-through. If not, you can tape around with black electrical tape or cover with foil. This is because the mycelium is photosensitive, and if it senses the light from the sides, it will start pinning on the sides and not on the top. This will reduce flush and lower yields, and it risks the casing as the mushrooms in the sides can rot and introduce contaminants to the casing due to the mushrooms rotting.

Doing the casing.
Grab all the materials we talked about a little earlier, and bring them to your work area. Make sure to be sterile at all times, it never hurts to be clean. Spraying a little (a lot of) Lysol® in the air will do you good since it will keep molds and spores at bay while you are working. Make sure your bowl and utensils are very clean.

This is the procedure for a casing using vermiculite:

  1. Spray Lysol® in your working area.
  2. Put vermiculite in the bowl. Put as much needed to make a one-inch (3cm) thick layer in the bottom of the tray/container.
  3. Take the water, and wet the vermiculite enough for it to be wet. Yet when you squeeze it, it should barely drip any water. (25mL water for each half cup of vermiculite).
  4. Now, take the wet vermiculite and spread it in the bottom of the tray/container.
  5. Now you should have something like in the picture.This will provide extra moisture to the mycelium. The amount of water necessary to achieve the right moisture can vary according to the grade of the vermiculite. If you are going to make a mistake, err to the drier side and mist when necessary.

  6. With your hands clean, take the colonized jars, and take the cakes out.
  7. Crumble the cake/s to about one or two cubic inch pieces

  8. Level the crumbled cake/s over the first vermiculite layer. A nice 1½" to 2" (38mm to 51mm) thick layer of substrate is desired. Make the top as level as possible. Fill the gaps between large chunks of substrate with smaller pieces of substrate.
  9. If you are still with me, your casing looks like this, and that is good. We are getting ready to do the final layer of the casing. We are going to do it a vermiculite only layer, but you can choose from other recipes for this.

  10. Get the mixing bowl and pour vermiculite in it. Slowly add water (25mL water for each half cup of vermiculite) and mix well. Do not over saturate it with water. It should almost drip when squeezed.
  11. Take the vermiculite and spoon it little by little over the substrate layer. Cover all the substrate completely, but do not pack it or over compact it. You can make this layer from ¼" to ½" (6.35mm to 12.7mm) thick. Also, make sure you get a very leveled layer.
  12. Cover with a lid (Saran Wrap® or plastic wrap will be fine) and place in a dark, warm place.

By now you should have a finished casing. It is important that the top layer is not packed down because then the mycelium will have a hard time poking through the layer. This will slow things down. Make sure that the casing is as level as possible as otherwise you will not achieve an even pinset.

Caring for the casing.
We already did the "hardest" part of the process. The rest is actually packed with fun and excitement as it is just waiting for the mushrooms to be picked. Also, since there is so much excitement involved, many newbies get desperate and lose their patience, something that can cost them their hard work. This is because they get anxious and start playing around, misting, fanning, poking, dunking, recasing, and just messing things which were nicely done the first time. That is the biggest cause of casings failing and getting contaminated.

After the casing is done, you place it in a dark, warm place to allow the mycelium to recover and colonize the casing layer.

Allow the casing to sit in there for 3-7 days more or less. Usually by then, the mycelium has poked through in several places. It is recommended that you patch with casing material the first areas in which the mycelium is seen first. This is to allow the rest of the casing to catch up and promote even pinning. You look forward to this, as it makes yields substantially larger.

When the mycelium appears to have colonized uniformly the casing, it is time to place in the terrarium.

The terrarium.
This are just briefs words about setting up a terrarium. Terrariums do not need to be elaborate or fully automatic. Although automatic setups that provide the ideal environment are great, many of us poor people can/will not afford them. But who needs to invest in a hundred-plus dollar environment when you can get by with around $20 of materials easily available at our favorite stores (hint: the ones that end with MART). For dummies' sake, lets take a look at what a very simple terrarium has and does.

A container that will actually be the terrarium. This can be any size as long as you have space above to allow the mushrooms to grow. An example of this can be 11-gallon clear plastic container.
For humidification, there are many options. The most cheap is hand-misting. It is simply what it is called. Perlite is great at mantaining high humidity and is very cheap and readily available. Cool mist humidification works better, but they require more space and additional maintenance. But they are worth the try.
Air exchange is very important. So unless you have an automatic method of circulating the air, you will have to do this manually. This is called fanning. Just take the lid off, and fan vigorously to remove the stagnant air. You can also add an aquarium air pump to replenish the O2 (oxygen) levels and fresh air. Keep in mind that molds, especially green mold, loves stale air and air exchange is the best way to fight it.


  1. An air pump does not do all the job of air exchange, but it helps bringing in fresher air and circulates it.
  2. To prepare the perlite for humidification, you first put it in a bowl. You add water to it until it is soaked wet, and strain with a colander. Spread evenly about in the terrarium floor. About an inch (3cm) depth is good.

Once inside the terrarium.
After placed in the terrarium, there is not much to be done to the casings. It is just a matter of providing the right conditions for them to fruit. This is what you would need to do:

  1. Fan three to five times a day. This is perhaps the most important aspect (along with humidity) in determining fruiting. Also, it removes stagnant air, which is desired by nasty molds.
  2. Spray the terrarium walls after you fan to bring the humidity up again. Also, you can spray the casing if it seems dry, as long as there are no pins at sight. But do not overdo it. One or two light mistings are okay.

When the casings are put in the terrarium, a humidity of more than 95% is desired to initiate primordia formation. Once pinning has begun, the humidity can be brought down to 85%-92% for cropping.

It is recommended that a light source be placed above the casings. Psilocybe cubensis are a photosensitive mushroom; this means, that it uses light to sense which way to grow.

The temperature for casings should fluctuate between 75°F (23°C) to 88°F (31°C) for optimal conditions. It can be lower, though growth will be considerably slower, or higher, though thermal death of the mycelium occurs at 106°F (41°C). Do not allow the temperature to rise above 95°F (35°C).

Food of the gods.
After 5-14 days of placing in the terrarium and maintaining the conditions described above, you should start noticing little hyphal knots forming. They resemble thick strands of mycelium and will develop into healthy mushrooms if the conditions are favorable. Some will not make it to their mature stage. These are called abhorts and can be consumed provided that they have not started to rot. You can find abhorts because they stop growing and their heads start changing color to a dark blue, then black. If they turn black they have just started to rot. Ironically, many believe that abhorts are primo in alkaloid contents (by weight compared).

After two days or so, those knots will become thicker and bigger. These are pins. You can spot them because they are a somewhat off-white color with a reddish-brown head. The head will become the cap.
Usually once you have a pin, in only a matter of days you will have BIG mushrooms. They grow very fast. It only takes a lapse of about 7-9 days for them to achieve maturity.

Wow, you made it!
Growing mushrooms is very easy. And casings are easy to do also. They are a great technique to master, as other mushrooms which you might have interest in growing require the knowledge of casing. With a couple of trial runs, you will find a technique and recipe that will work for you greatly and open many doors to experimentation.


More on Hongus Tek : The Casing Layer  : Casing Overview : Back to the Archives : Shroom Glossary

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