The Giant Pancake Tek requires quite a bit of colonized substrate and must be at least 6" inches deep. It is preferable to use different layers of mixtures to be colonized by the mycelium. For example you can use (pasteurized or sterilized) compost, freshly chopped wood sawdust, potting soil, 50/50+, dung, worm castings, and possibly others. Since it will be a very deep substrate it will take quite some time to finish colonizing therefore you might not want to use anything with straw because of it's vulnerability to contaminants. But basically you can mix and match in layers. You don't have to use different mixtures of substrates if you don't have them available. The concept is to colonize as deep a substrate as possible without running into contaminants.
Here you see a mixture of fresh neutral hardwood sawdust from a freshly chopped non-infected treebranch. Store bought mulch doesn't work as well. It has been mixed with a nutrient rich pasteurized compost. NEVER USE "MUSHROOM COMPOST" for mushroom cultivation. Mushroom compost is the spent soil mixtures that were used for mushroom cultivation farms that is still suitable for plant growing, but not for mushroom growing.
Lay 2-3" of this mixture on top of a thin layer 3/4" inch of pasteurized or sterilized potting mixture with any big chunks removed from it on bottom, which will eventually be the top on the cake when it's flipped.
Now lay another 2-3" inches of a pasteurized or sterilized potting mixture with little to no vermiculite in it.
Another 1-2" inches of a 50/50+ mix containing peat moss and vermiculite with added lime and calcium carbonate if available or crushed oyster shells.
On top of the 3-4 layers of mixtures (remember it doesn't have to be in layers if you only have 1 kind of mixture available) you will place your colonized substrate. In the picture many colonized cakes cut vertically were used. You cannot mix and match strains or species of course. Lay the slices down and try to leave no gaps in between the cake slices. We are trying to create a sheet of colonized substrate. For this type of casing you don't want to mix the colonized substrate into the mixtures, as it might be preferable with other types of casings.
On top of your substrate lay another 2-4" inches of 50/50+ pasteurized or sterilized.
Cover the bin with its lid. Place the bin in a semi-dark location inside or outside with temps anywhere between 50 to 80 degrees. Keep in mind the colder it is, the longer it will take to colonize. Optimum temperture would be around 68-75.
Keep the top of your casing moist always by regularly misting with a pump style water sprayer. Use spring or mineral water. Every 2 weeks mist with a mixture of mineral water and lime. The lime must be boiled separately with distilled, spring or mineral water and then added to the mineral water and mist generously. Once the top of the bin is fully colonized, wait longer until you see the first couple of mushrooms coming from the sides or pins on top. Usually the first few will appear on the sides. This means that it is colonized through the bottom, and time to flip the pancake into a bigger bin. Use a bigger bin and place about 3-4" inches of perlite wet only by peroxide and no water. Mix the peroxide into the perlite well with some gloves or just your hands, but the peroxide might hurt your skin. Once that's mixed well and the perlite feels very moist, lay some dry vermiculite in the spot that the pancake is going to lay in leaving the edges with the perlite only showing. The vermiculite layer should be about 1/4" inch tall.
Now flipping it is a bit tricky sometimes. What works best is to lay 1 or 2 large garbage bags on the floor. Lay the side of the bin on the floor on top of the garbage bag and carefully, smoothly and swiftly tilt the bin upside down with it's side always touching the bag. This will dislodge the colonized pancake block from the bin and into the plastic bag. Now try and move the block between two or 3 people into the bin on top of the dry vermiculite that was laid down. If the block breaks into several pieces all you have to do is put it back together in the bigger bin like a jigsaw puzzle. Another way it could be done is by tipping the pancake in the middle of the bag and by evenly pulling on the bag with at least 2 people as you bring it to the bigger bin in the center and then cut the bag at the bottom surrounding the pancake. If you don't have any helpers, you can break the pancake into 2-4 pieces and put it back together in the bigger bin by yourself and the pancake will tie the pieces back up with mycelium in a matter of days if not tampered with.
Sprinkle vermiculite on top of the block and mist thoroughly. Cover with it's lid and allow to rest for few days. The bin must be aired out a minimum of 2-3 times daily. Mist twice daily with fine mist as you wipe away exess moisture from the top of the lid and the sides of the bin after misting. The will allow for a more evaporative moisture and allow for the perlite to do it's job better.