How to use Grain Spawn Bags and Mushroom Grow Bags

Mushroom grow bags are a convenient and easy way to grow mushrooms at home. There are a variety of different sizes and options available, but most all mushroom grow bags will feature a gas exchange filter.

Using spawn bags is a relatively simple process, however most new growers can be intimidated by the process. That said, this is a quick and focused guide on how to fill, fold, sterilize and use your spawn bag.

Items Needed:

  • Mushroom Grow Bags
  • Spawning Substrate (grain bag)
  • Impulse Sealer, bag clamp
  • Pressure Cooker or Autoclave


  1. Open your bag, pushing out the gusseted sides and allowing it to stand up. Flatten the bottom to avoid grains from getting stuck under the bottom flaps
  2. Fill the bag with your preferred spawn substrate. Do not fill up to the filter; leave a few inches of space. 
  3. Fold in the gusseted sides, bringing the front and the back together. 
  4. Wrap the bag over itself tightly. 
  5. Place in sterilization vessel and sterilize. When using a pressure cooker you will need to maintain 15PSI for 90-120 minutes. 
  6. Remove from heat and allow the bags to cool in the vessel. 
  7. Remove the bags and seal using an Impulse Sealer or other method. 
  8. Store in a cool environment until ready for use. Use the bags within 3 weeks for the best results. 

Looking for quality mushroom grow bags? Check out our bags which feature multiple filters, with and without injection ports. 

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