Cultivation of Psilocybe cubensis on sterilized rye grain

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We cultivate Psilocybe cubensis on sterilized rye grain. This species can be grown on a wide variety of substrates such as rice, birdseed, pasteurized straw, compost and dung. We however think that, of all of these, rye grain is the most suitable for the small-scale cultivation of Psilocybe cubensis for research purpose because it's both cheap and easy to work with. Most other grain types have the disadvantage of having to be boiled or steeped before sterilization or else the kernels will clump together. Cultivating mushrooms on straw, compost or dung is possible but an art in itself.

Preparation of rye grain spawn

We prepare rye grain spawn by combining equal volumes (1 cup) of rye grain and water in a jar. In our case this comes down to (roughly):

175 grams of rye
230 ml of water

We use 720 ml jars with metal lids. After the water and rye have been filled into the jars, the lids are put on but NOT screwed tight! The lids MUST remain loose! Then a double layer of tinfoil is crumpled over the lid and top part of the jar. Now the jars are ready for sterilization. As an extra precaution some kind of filter (filter disc, Tyvek) can be inserted under the lid. For this method the lids must be punctured to facilitate air exchange.

Different ratios of rye and water have been suggested by literature. We recommend you do a test batch with different ratios of water and rye to see what works best for you. The 1:1 ration we use contains the maximum amount of water the we could use. When using larger volumes (big jars or bags) less water should be added or the bottom kernels will turn to brown goo. When using the colonized rye grain to directly fruit the grain can be somewhat wetter then when it's used to inoculate (non sterile) bulk substrate. Exploded kernels with their starchy inside exposed can flourish with bacterial bloom upon contact with non sterile materials.


The jars should be sterilized in a pressure cooker or autoclave, a normal pot will NOT suffice. First a layer of water is poured into the cooker. The jars are placed in the pressure cooker making sure that the lids are loose!

Now sterilize the jars for one hour according to the directions supplied with your pressure cooker. If you are using bigger jars then the sterilization time should be prolonged. (we sterilize 1.5 litre jars and spawnbags always for 2 full hours). Once the cooker is no longer under pressure the jars should be taken out and the grain in the jars should be shaken loose to mix the wet and dry kernels. The jars should then be allowed to cool in a clean place. Always check the jars for cracks before shaking! When the jars have cooled to room temperature inoculations can take place. As the jars are cooling down the lids should remain loose or else they will form a vacuum inside of the jar. When this vacuum is broken, dirty air is sucked inside and the jar will most likely contaminate.


When the jars have cooled down completely they are ready to be inoculated. If you inoculate the jars while they are still hot the spores or mycelium might get killed. You can use a spore syringe, mycelium syringe, agar squares or whatever kind of inoculant you want. The most important thing to remember is to WORK CLEAN!
When using syringes always flame the needle before commencing inoculations. When using agar squares always flame the scalpel! Be careful!

Even a simple hood made of a cardboard box prevents prevent drafts and subsequently contamination. Do not expose the sterilized grain to air longer then absolutely necessary. Open the lids of the jars just a crack and work swiftly. After inoculation the lids of the jars are closed and the jars are shaken. Then the lid is loosened again so the mycelium will be able to breathe.

Use your common sense and do not put yourself in risky situations. Again, most disinfectants are both toxic and flammable. When working in the presence of an open flame do not use any kind of other flammable materials. Also, do not overdose on disinfectants, most are seriously dangerous to your own health.
UV disinfectant lights are dangerous as they can cause damage to your eyes and cause skin cancer.


After inoculation the jars are put in a clean and draft free location. Mycelial growth has its optimum at 30C, but beware! Incubating jars generate heat themselves! The mycelium will grow in a wide range of temperatures. We normally put our jars at room temperature (20C) or slightly higher. When mycelium starts to grow in only a few spots we shake the jars to redistribute the colonized kernels. This speeds up colonization dramatically. Depending on the temperature and the method of inoculation the grain can be completely colonized in 5-20 days.


When the grain in the jars is completely colonized it needs to be cased. For this purpose we use 1-litre disposable plastic trays. The colonized grain kernels of one jar are shaken loose are poured into a tray. If there are lumps within the grain these can be broken up with the clean rim of the jar. The surface of the grain is leveled evenly. Using a big spoon and a fork the grain is now covered with a thin layer (1.5-2.0 cm) of casing soil. We always try to keep the casing surface even while at the same time keeping it rough (with small valleys and hills) The cased tray is then covered with tin foil and put in a clean location (20-25C). Within a few days you will notice the mycelium growing through the casing soil. Depending on the strain (some strains fruit earlier and easier then others) the casings are now ready to be exposed to air and light to start the fruiting cycle.

Recipe and Preparation of the casing soil

We use the following recipe:
10 parts of peat
5 parts of vermiculite
2 parts of limestone (Marl)

The ingredients are mixed in dry form and while stirring water is added. The amount of water of course depends on the moisture content of the peat. The object is to get as much water in the casing soil as possible without turning it into mud. If the casing gets too wet just add a little more dry ingredients. This casing soil is then filled into oven bags (made of nylon), autoclave bags (PP) or jars and these are sterilized for one hour in the pressure cooker. When the soil has cooled down to room temperature it's ready to use.

Often an alternative method that utilizes the microwave oven can be used. The moistened casing soil is filled into heat resistant bags or jars and is sterilized for 20 minutes at maximum power in the microwave. Just add some extra water to make up for water loss from escaping steam.


Some cultivators use very elaborate set-ups with humidifiers, cool-mist devices and such. We have never found this necessary. The fruiting containers that we use consist of simple clear plastic bins that are covered with polyethylene sheeting. These bins are stackable and thus very space efficient. For air exchange some hole are melted in the sides of the bins. These holes can be covered with mesh to keep out flies.

Basically, five cased trays are put in one bin and the evaporation from the casing surface is enough to maintain the proper moisture inside the bin. The holes provide some air exchange. We always cold-shock the harder-to-fruit strains (we put them in the fridge for one night before putting them in the bins). For easy fruiting strains (i.e. Ecuador cubensis) this is not necessary.

The casings are misted each day and the casing is never allowed to dry out. Directly after a flush is picked watering is increased because the maturing mushrooms pull a lot of moisture from the casing soil. It's very difficult to give explicit directions on a watering regime. You will have to develop a 'feeling' for it.

Depending on the strain the first pinheads will appear 6-15 days after putting the casings in the bins. The mushrooms will mature in 5-7 days after which they can be picked. We normally let the casings produce 3 flushes, but they may (when watered properly) produce as much as six flushes! Keep the surface of the casing as clean as possible by removing dead pinheads (aborts) as these can lead to molds showing up on the casing surface.

Casing Teks : Inoculation Teks : Shroom Glossary