Preparing & Inoculating Grain Spawn

Part 2 : Unit 3 : Preparing and Inoculating Grain Spawn

This is the first proper meal you’ll be cooking for your mycelium – a hot, steamy mason jar with hydrated corn kernels inside. In this module you’ll learn to hydrate the corn, sterilize it in mason jars using a pressure cooker and then inoculate it with some liquid mycelium. If all goes well, the mycelium will slowly grow and spread in the jar. You can break up the grain and mix the contents of the jar once there’s been about 30% colonization. This spreads the mycelium around more evenly among the grain and gets the jar colonized quicker. Once the mycelium has fully spread, or “fully colonized the grain,” it will be ready for the next step: mixing it with bulk substrate. Let’s get ready to cook some delicious grub for our mycelial friends!

Colonizing jar of mycelium
Colonizing jar of mycelium

Preparing Grain Spawn in Mason Jars

Items needed
Notes & Tips

Video Tutorial : Hydrating and Sterilizing Grain Spawn in Mason Jars

The video markers above 👆🏼correspond to the the various Steps in this Unit. Click on them to skip to a Step.

Step 1 : Hydrate the Corn in Simmering Water for 3-4 Hours

You’re going to need an uninterrupted 4 hour block for this next step. Clean out the pressure cooker pot and add 4 lbs of dry corn kernels. Fill the pot half way with water and place on the stove. Turn on the heat to “high” and bring the water to a boil. Once boiled, turn down the gas to low so that the corn simmers in the water. Add water to the pot if needed, as water will evaporate and be absorbed by the corn. Keep simmering for about 3-4 hours, until the corn is well hydrated and can be crushed between your fingers. 

Step 2 : Dry out the Corn in a Sieve or Tray

Once the corn is ready, carefully pour it out into the sieve and drain out all the water. Allow the grain to steam off for about 30 minutes, occasionally mixing it around to expose underlying corn. Wait until the corn has no significant water on its surface before finally placing it in mason jars. You can use the “is the paper towel wet” test to see if the grain is dry enough or not. Dab a paper towel into the grain for a few seconds – if it has visible wet stains, it’s not ready yet and requires more drying. Don’t let your corn dry for more than several hours or else it will dehydrate.

Step 3 : Place Grain in Mason Jars and Pressure Cook for 90 Minutes at 15 PSI.

Once the grain is dry enough, put it in the mason jars, filling them about 3/4 of the way. You want to leave enough space in the jar to mix the grain later on. Make sure the silicone seal is in the lid and close the jar tightly. Cover the jar lid with aluminium foil. Proceed to  fill the rest of the jars in a similar fashion. Once done, place the 6-7 mason jars in the PC and pressure cook for 90 minutes at 15 PSI. Allow PC to cool off completely before opening.

Inoculating Grain Spawn with Liquid Culture

Items needed
Notes & Tips
Psilocybe cubensis mycelium colonizing grain spawn
Psilocybe Cubensis Mycelium Colonizing Grain Spawn

Video Tutorial : Inoculating Grain Spawn with Liquid Culture

The video markers above 👆🏼correspond to the the various Steps in this Unit. Click on them to skip to a Step.

Step 1 : Clean and Disinfect Everything

Wipe down and disinfect your workspace and mason jars. Remove the aluminium foil from the liquid culture jar and wipe down the injection port with alcohol. Do the same to two of the grain jars. You will be inoculating the grain jars in batches of two or three.

Step 2 : Unpack Sterile Syringe and Hypodermic Needle

Carefully unpack the sterile syringe and remove it from its package, without touching the syringe tip. Next, carefully remove the hypodermic needle from its wrapper and place it on the syringe tip firmly while still keeping the safety cap on.

Step 3 : Draw out 10 cc of Liquid Mycelium from the Liquid Culture Jar using the Syringe

Remove the safety cap from the syringe and insert the needle into the injection port on the LC jar. Tilt the jar slightly so that it’s facing downwards and the liquid mycelium reaches the inserted needle. Be careful while you tilt the jar – try to avoid getting the air filter inside the jar lid wet as it might bring on contamination of the LC jar itself. Once you can see some mycelium around the inserted needle, withdraw a few cubic centimeters (cc) of liquid.

Step 4 : Inject Liquid Mycelium into Grain Spawn Jar via the Injection Port

Remove the needle from the Liquid Culture injection port and insert it into the injection port on the grain spawn jar. Press on the syringe to expel the liquid mycelium into the grain spawn and remove the syringe. Wipe down the injection port and jar lid cover with alcohol and cover the jar lid with aluminium foil. Shake the jar well to get all the liquid distributed evenly in the jar amongst the grains. You want to avoid pooling of liquid inside the jar. Complete this process for all grain spawn jars, while using new (or re-sterilized) needles for each batch. Place jars in a clean, dark space with not too much airflow or traffic, at temperatures around 22-27 °C or 70-80 °F for incubation.

Step 5 : Allow Jars to Colonize. If Needed, Break and Mix Grain Spawn at 30% Colonization

After 3-4 days you should see some white mycelium peeking out from the grain, slowly colonizing the jar. If you injected a bunch of liquid culture into the grain spawn jar and mixed it well, then the mycelium growth should be pretty even across the grain throughout the jar, speeding up the time to full colonization. However, if the mycelium isn’t growing relatively evenly across the jar and there are large patches of grain which are not covered in mycelium, then there’s something you can do to help speed things up. When the jar gets to about 30% colonization, re-mix the grain inside the jar by tapping the jar against a book or a towel and breaking / mixing the grain spawn around. Do this only if necessary though, as mycelium prefer not to be broken up and banged around. The jars are considered “fully colonized” once all the grain is covered in mycelium throughout the jar. The jars pictured to the right are about 6 days into incubation at 26°C or 79°F. They are not yet fully colonized and don’t need to be broken up and shaken.
Colonizing magic mushrooms jars
Colonizing Magic Mushrooms Jars

Next Unit: Preparing, pasteurizing and inoculating bulk substrate for your fungi friends. Here you learn to make CVG substrate, mix it up with your colonized grain spawn and set up your monotub for incubation.

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