How To Inoculate A Sterilized Substrate Bag

If possible inoculate under a hepa filter flow hood or in a controlled still-air environment like a glovebox to reduce the risk of contamination. If not possible, you should work in a small, clean area with the door and windows closed to reduce airflow. Clean the area extensively a few hours before you plan to inoculate. 

TIP: The cleaner the environment used the less possibility of contamination occurring, so it pays to really clean your inoculation area before starting. Better clean now than contaminated later. 

Step 1:  Thoroughly clean your hands and arms. Wipe down your inoculation area with alcohol. Put on your pair of gloves. 

Step 2: To prepare the grain bag for injection, unroll the bag top and slowly pull apart the gussets to allow the bag to inflate enough for spore injection. Use a sterile alcohol swab to clean the area you will inject into.

Step 3: Take your syringe and wipe with a sterile alcohol swab. Make sure to wipe syringe with alcohol before each inoculation to ensure possible contaminates aren't accidentally transferred from one bag to another.

TIP: A alcohol wetted paper-towel or cloth works well to clean both bags and syringe without the small size of a alcohol wipe. 

Step 4: Take 2-3 ccs of liquid culture or spore solution and inject it into the bag.  Attempt to spread the spores in as wide an area as possible by mixing the grains once inoculated. Apply a small piece of tape to cover the injection point.

Step 5: Set the grain bag in a place where it won’t be disturbed. For fastest growth regulate the temperature to 75°F - 80°F. Within 3 to 10 days (species dependent) after inoculation, you’ll start to see initial signs of growth. Do not disturb the mushroom substrate bag during this stage. 

TIP: Pressing the filter against the plastic of the bag will limit the gas exchange during the colonization phase and slow the colonization process.

Step 6: After 2 to 4 weeks, the mycelium will have colonized about 75% of the bag, use your hands to break up the grain through the outside of the bag. Breaking up the grain will mix the mycelium and hasten the last phase of colonization.

TIP: Don’t mix until colonization has reached at least 70%. Earlier will slow the growth of the mycelium. 

Step 7: Within a week the mycelium will colonize 100% of the bag. At this point, it is time to spawn the colonized grain to a bulk substrate.

If you are using BOOM Blocks and prefer fruiting right in the bag you can skip the bulk substrate section and go right to casing or fruiting conditions. 


Bulk Tub Substrate Phase

Once the inoculated grain spawn has attained 100% mycelial colonization, you can spawn it to bulk substrate. The recommended spawn ratio is 5 pounds of bulk substrate material for every 2 pounds of grain spawn. Open the colonized grain bag and dump the grain into the bulk substrate. 

Mix the grain and substrate thoroughly together. Ensure that the new substrate and the colonized grain is well-mixed.

TIP: You can mix the substrate in a monotub, modified plastic bin sgfc or any other homemade fruiting chamber. You can also mix directly in the mushroom grow bags. It’s your choice. 


Add Hydrated Mushroom Casing

Spread the casing as a uniform layer across the top of the substrate with your gloved hands. Ensure that the casing remains loose and do not pat it down.


TIP: Aim for 10mm or (about one half inch) 1/2" depth of casing layer on top of the colonized substrate.

Place the mix in a dark place with a temperature near 80°F. It will take 1 to 2 weeks for the new substrate and casing to completely colonize. Colonization is complete when the substrate turns completely white. Once the substrate is completely colonized, you can introduce the bag to the necessary conditions for fruiting. 


Introducing the Tub or Bag to Fruiting Conditions

Step 1: It’s time to introduce the colonized substrate to fruiting conditions. Lower the temperature to around 60°F. and open the top of the tub or bag to introduce a large volume of fresh air. 

Step 2: Begin to mist the colonized substrate two to three times per day for the duration of the fruiting stage. Use a clean water bottle to mist the substrate. 5 or 6 sprays of water are usually enough. Aim to keep the area very damp without puddles of water forming. 

Step 3: Once the substrate has been introduced to fruiting conditions you’ll start to see primordia in about 10 days. Primordia are tiny pinheads that turn to mushrooms. Continue to mist and fan.

Step 4: Primordia will turn to pins in just a few days, and form mushrooms very quickly. Soon the mushroom veils will start to open up. Once the mushroom caps have opened up they are ready to pick! Grasp the mushrooms from the base and twist to remove them from the substrate. The less damage done when harvesting the faster the next crop can begin to fruit.

TIP: Take care not to leave mushroom fruitbodies behind when harvesting, these will cause contamination later.

Step 5: Once all the mushrooms have been picked dunk the entire mycelial block in cool water and allow the block to sit for 6-8 hours. Drain the water and cover the block with casing again. Allow a week for the mycelium to recover then re-introduce fruiting conditions. You can harvest many times from the same colonized tray or bag by repeating the steps.

TIP: Once the substrate has stopped producing a large amount each harvest you can use the spent material to create an outdoor mushroom patch.