Bulk Substrate Tutorial Using Pre-Pasteurized Compost & MycoBags





Previous Tutorial: Spawn Production
Once your inoculated grain spawn has reached 100% mycelial colonization, it is now time to spawn it to a bulk substrate, like our pre-pasteurized mushroom compost. If you don't know how we got to this step, please read the previous tutorial.
Once the bag is completely colonized with mycelium (you should not be able to see any uncolonized grain), break the grain up with your hands through the outside of the bag. Make sure the grain gets broken up completely and thoroughly.
Cut off the bag containing 5 lbs. of pre-pasteurized mushroom compost directly below the filter with a clean pair of scissors.






The spawn ratio that we recommend is two pounds of colonized grain spawn per five pounds of pre-pasteurized mushroom compost. Cut off the bag of broken-up colonized grain (the bag that you previously broke up) directly below the filter-patch with a clean pair of scissors.






Dump the broken-up grain bag in to the 5 lb. bag of compost. Do the same thing to another 1 lb. bag of colonized grain, mixing a total of two pounds of grain to five pounds of substrate.
Mix the grain/compost mixture by massaging the outside of the bag. It is very important to make sure that the mixture is mixed up thoroughly and that the grain is distributed evenly throughout the bag.






You can proceed in one of two ways, you can introduce the mixed substrate to a homemade fruiting chamber (usually a modified plastic bin), or you can introduce the mixed substrate to mushroom grow bags. The vessel that you choose to grow your mushrooms in is really a matter of personal preference. Our preferred method of growing is with mushroom grow bags, as we find them easier to work with. The remainder of this tutorial will demonstrate the correct procedures for using these grow bags. Pour half of the 5 lb. bag of mixed grain and substrate in to a brand new filter-patch bag and pour the other half of the substrate in to another brand new bag. It is best to do this step in a small, clean workspace with limited airflow. Make sure to wear gloves during this step.
Seal the bag with a mushroom bag clamp and tube approximately two inches from the top of the bag.






Put the bag in a dark place that will maintain a temperature between 75-81°F. Disturb the bag as little as possible during this time period and do not open it until colonization is complete. It will take approximately 5-10 days for the substrate to completely colonize with mycelium (you will be able to tell if it has completed colonization when the substrate has turned completely white). The bag should look like the picture above. Once you reach this point, it is now time to introduce the bag to fruiting conditions.

Next Tutorial: Fruiting Tutorial
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