Preparing your own grain spawn in jars is an economical way to produce mycelium in bulk quantities, while keeping some separation between the “cakes” in case any contamination is introduced. The WBS Instant Pot Grain Spawn Tek is easily accessible and suitable for home cultivators, and you likely already have an Instant Pot laying around from when we all lived through the plague! It also uses a widely available nutrient source, wild bird seed.
This tek was derived from Helios’ Mushroomery’s Instant Pot Popcorn Tek, and was originally perfected using Royal Wing Wild Bird Food available at Tractor Supply. You should be able to use any mixed bird seed for this.
The process will result in 4-5 sterilized jars for each 2-3 jars of dry WBS. I would recommend repeating the process about 3 times, to yield 12 jars. You should experiment to find out exactly how much of your specific WBS is needed to make the desired amount of jars, and what the desired cooking time is for the correct hydration.
Please ensure that all your equipment and utensils are clean prior to preparing your grain jars.
You Will Need
Read First
Washing the Bird Seed
Remove the Instant Pot’s inner pot, and add the dry bird seed to it. Wash the bird seed using clean water for a few minutes, stirring until the water is very cloudy. Cold, filtered tap water will do.
Use a small sieve to skim off plant debris, such as stems and leaves, and remove black sunflower seeds. These should be discarded and the bird seed should be stirred and skimmed until no more black seeds are left floating.
When most of the excess starch and dirt has been washed off of the bird seed, you may drain off the water and add new water, about 2 inches above the bird seed. Again, filtered tap water is fine. At this time, you may also add a tablespoon of gypsum. This adds calcium to the bird seed to encourage the growth of mycelium.
Preparing the Drying Station
Our drying stations will utilize baking racks, disposable grill trays, and cotton rags. We should need to set up three of these for the amount of grain we’re producing. The preparation is simple – lay out the racks, then a tray on each rack, and then a rag on each tray.
Simmering the Bird Seed
Now that the bird seed has been washed, the inner pot may be returned to the Instant Pot and it should be set to Pressure Cook for just 10 minutes, with the “Keep Warm” setting disabled. The Instant Pot’s vent should be set to “Sealing”.
Running the pot for only 10 minutes ensures that the bird seed is quickly heated to boiling temperature and fully hydrated, building minimal pressure. Once the timer runs out, immediately move the vent to “Venting” and allow any pressure to vent before opening the lid.
Drying the Bird Seed
You can now immediately move the bird seed to the drying station. Use the cotton rags as pot holders to remove the inner pot, and strain away the excess water. Please do so carefully to avoid any risk of burn injuries.
Then, scooping the bird seed from the strainer using an ice scoop, transfer it to your drying trays. You may lay it on quite thick, maybe around 1/2″ to 3/4″ thickness, but no thicker. It will continue to evaporate steam from the top and bottom for the next two hours. You may periodically stir and reflatten the bird seed to encourage evaporation.
While waiting for the bird seed to dry, wash and dry the inner pot so that it may be used again for the next steps.
Filling the Jars
Now that the bird seed is sufficiently dry, you should load it into the jars. Use the ice scoop to scrape the bird seed away from the fabric and place it into the jars. You should lightly tap the bottom of the jar on the table to ensure that the bird seed is evenly and loosely packed. Fill the jar up to about 3/4 of the way.
Now you can add a modified lid and a ring to each jar, and cover the lid with aluminum foil to prevent the filter paper from getting wet during sterilization.
Sterilizing the Grain Jars
You may now sterilize 4 jars to a time in the Instant Pot Duo by placing the trivet in the inner pot, adding water until it comes just above the trivet, and then lowering in 4 prepared jars. Attach the lid and set the vent to “Sealing”. Pressure Cook the jars for 1 hour 30 minutes, with the Keep Warm setting disabled. Allow the pot to depressurize on its own before removing the jars.
These jars may be prepared up to a week in advance, stored in a room temperature area with the foil still tenting the lid. Remove the foil before using the jar, and do not use the jar until it feels completely cool to the touch, typically after 8-12 hours.
