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Grain Spawn Standard Operating Procedures This SOP is adapted from Penn State Spawn Lab Procedures 1) for the home user who may not have access to a laminar flow hoods, Erlenmeyer flasks, Autoclaves, etc.


Step 1 Prepare a container for the pressure cooker, either:

(1) 8oz Wide Mouth Canning Jar with lid modified with a self-healing inoculation port and fresh-air-exchange port; or

(2)Use a small mushroom autoclave-safe grow bag with an innoculation port and fresh-air-exchange port.

Step 2 Measure out the three ingredients (1) ORGANIC RYE WHOLE GRAIN - Using a measuring cup, about 50 ml (or if using a kitchen scale, about 30 grams) (2)LIME POWDER (Calcium sulfate) - 1/2 teaspoon Calcium Carbonate (3) GYPSUM POWDER (Calcium sulfate)- 1/4 teaspoon WARM WATER - 60mL (distilled water preferred but not required. Any water about ph7 will be fine.)

Step 3 Prepare the bag or jar for sterilization. Add all ingredients and seal your canning jar or grow bag, and mix the ingredients gently.

If using a canning jar, make sure to twist the ring hand tight. It should be airtight and there is no concern of overpressurizing the jar or having it hold vacuum because of the fresh-air-exchange port that allows the jar to breath. Put a piece of foil over the top of the jar so that you can minimize the risk of contaminating the top of the lid from when you transfer it out of the pressure cooker into your still air box or Laminar flow hood for inoculation.

If using a mushroom bag, try to push out as much air as possible, and seal the top with binder clips, a hair iron, rubber band, or even tie the top off in a nice tight knot.

Step 4 Sterilize the grain Place the jar(s) or bag(s) into pressure cooker, and maintain 15 psi for at least 90 minutes for smaller batches. Bigger batches will take longer. It is theoretically possible to sterilize for too long, you will know it is too long if the seeds have exploded out of their hulls.

Step 5 Inoculate the sterilized grain Allow the sterilized grain to cool to room temperature. Transfer the sterilized jar or bag to your still air box or Laminar flow hoodand using a sterile syringe tip, inject your liquid culture through the self-healing inoculation port. Usually, I use an alcohol burner2) to get the steel syringe tip wet hot, cool it slightly with a single-use alcohol wipe, squirt out a few drops to clear the barrel of any microbials that might have survived the flame and alcohol, before injecting into the sterilized grain.

If your syringe tip is long enough, try to distribute the liquid culture in different spots of the grain so the entire mass will colonize more quickly.

Step 6 Wait for colonization Depending on your ambient conditions and your particular cultivar , you should begin to see fuzzy white mycelium growth within 2-4 weeks. The more fully colonized the grain is, the more success you will have when you transplant3) the colonized grain to your grow substrate.

sop_rye_grain_spawn.txt · Last modified: 2020/10/23 14:14 by mwikiadmin