colonizing grain spawn bags mycelium

How to Inoculate Grain Spawn Using Injection Port Bags

Injection port bags offer an easy and contaminate-free way to inoculate grain spawn when growing many types of mushrooms.



  • Prepared grain spawn bag with an injection port.
  • Spore Syringe or Liquid Culture Syringe
  • Paper towels


  • Butane/propane torch lighter
  • Surgical mask
  • Surface disinfectant
  • Latex gloves (optional)
  • Air sanitizer
  • Still air or glove box (optional)
  • 75% Rubbing alcohol


IMPORTANT NOTE: Colonizing mycelium is highly susceptible to contamination from bacteria, molds, and other airborne contaminants. Therefore, it is of utmost importance that you choose a clean area to perform your mycology work. Make sure there is no moving air in the room, and to disinfect your surfaces and equipment as well as spray an air sanitizer before working with your mushrooms. You’ll want to treat your work-space as a clean room; maintaining a sterile environment as much as possible.


1) Clean your work area and prepare the spore syringe:

  • Put on your gloves and mask.
  • Wipe down your work area completely with rubbing alcohol and spray an air sanitizer if available. It is best to find a place to work with limited air flow as to cut down on the potential for airborne contaminants.
  • Arrange all utensils so that your spawn bags, culture syringe, rubbing alcohol, gloves, paper towels, micro-pore tape and flame are all within reach.

2) Prepare grain bags:

  • Wipe down the grain bag with rubbing alcohol.
  • Most grain bags will arrive in compact form. The first step is to break up the grain as well as to suck air into the bag. break up the grains by gently massaging the bag. To inflate the bag, pull the gusseted sides outward allowing a little air to enter the bag through the filter.
Preparing a grain spawn bag for spore innoculation


Inject Culture:

  • Shake up your spore syringe so that the mushroom spores are evenly distributed.
  • Remove the cap from your syringe and hold the tip of the needle over a flame. You will heat it until the metal glows red hot. Give it a second to cool and then wipe it with your alcohol paper towel.
  • Wipe the injection port using your alcohol rag. Then insert the needle through the injection port.
  • Inject approximately 1-2 cc of the spore solution per lb of grain.
  • Wipe down your needle with an alcohol wipe/paper towel after each injection. 
  • Remove the needle and put the cap on.
  • Massage the bag to spread the culture solution around the bag.
  • Set the bag upright making sure there are no stray grains at the top of the bag.


Once your bag has been inoculated with spore solution or liquid culture, you will need to induce colonization.

  • Place your inoculated bag upright in a dry, dark area with an ambient temperature of 75°F – 80°F degrees.
  • Depending on the species, within 4-10 days you will begin to notice the beginning signs of white mycelium growth. Do not disturb the bag at this time.
  • After 2-4 weeks your spawn bag should be 75% colonized by mycelium. Once at 75%, you will want to break up the mycelium; mixing the colonized grains with the un-colonized grains. This is done to speed up growth.
  • After mixing, place the bag back in the colonization area. After one-two weeks the bag should be fully colonized and ready for use.
colonizing grain spawn bags mycelium

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