How to Make Mushroom Spawn

1. Prepare your workspace. A small shed or closet is the best option. Disinfect the area with at least a 10-percent bleach-to-water solution. Make sure the area can be enclosed either by a door or tarp, then add the HEPA filter air purifier.

2. Sterilize all of the implements needed for the spawn-production process. Put anything you cannot buy sterile into polypropylene autoclave bags and sterilize in an autoclave in small batches. Don't bring anything into your work area until it is sterilized. Everything that is used during the process needs to be sterile, this includes you, the room, the air and especially the implements and medium. Follow the instructions for your autoclave; sterilization generally occurs at above 200 degrees F with about 15 psi of pressure for 45 minutes.

3. Make your spawn. Place a small piece of mushroom on an agar medium in petri dishes, keep it moistened and under the proper temperatures for that particular mushroom; the mycelium will grow out and fill the dish in about two weeks. Agar medium is a gelatinous substance made from seaweed cells that is commonly used in laboratory work.

4. Transfer the mycelium when it has just filled the petri with long, healthy strands. Don't let the mycelium grow too long in the petri dishes. Transfer the mycelium to the sterilized grain in jars. Allow it to colonize for about two to four weeks under the proper temperature for the particular species of mushroom.

5. Observe your jars. When they are filled with healthy, white filaments, you have achieved grain spawn. Mushrooms will grow right out of the jar of grain spawn, or you can use it to inoculate more grain. If you repeat the process, one jar of grain spawn can produce up to ten more.