Mushroom Spawn Bags

mushroom spawn bags

Whether you grow mushrooms as a hobby or for commercial sale, incorporating the use of mushroom spawn bags can be a game-changer.

Not sure what mushroom growing bags can do for you?

Inside this guide, I break down what a mushroom spawn bag is, the benefits they provide, and features to look for so you can increase the ease and success of cultivating your mushroom crops!

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What is a Mushroom Spawn Bag?

A mushroom spawn bag, also known as a “grow bag” or autoclavable polypropylene filter patch bag, is an alternative to using glass jars to hold the grain or sawdust medium from which the mushrooms will grow.

What happens inside a mushroom spawn bag?

Successful mushroom crops begin with mycelium, which is the living tissue that forms into mature mushroom caps.

Inside a spawning bag, the fungal cells of the mycelium feed off the growing medium and use the material to spread its tendrils throughout.

For optimal success growing mushrooms, having a healthy abundant batch of mycelium spawn is a critical first step.

Using mushroom spawn bags can increase your mycelium inventory, which is especially helpful when you are growing specialty mushrooms like:

  • Lion’s mane
  • Oyster
  • Wine cap
  • Shiitake

The Benefits of Mushroom Spawn Bags

  • Sterilization Spawn bags are internally sterile, and most bags can withstand the high temperatures found inside a pressure cooker or other sterilizer.Bags deter the growth of common infections, like Bacillus or “wet spot” disease, which can ruin your mushroom crop.
  • Space savings Bags provide significant space savings over jars when it comes to storing, spawning, and fruiting mushrooms.Bags hold the same, if not higher, amount of substrate. Bags fit compactly next to each other, which saves space and means more bags can fit into your mushroom growing area for harvest later.
  • Disease control In the event you see infection, you can easily toss out the whole bag without fear it will taint the rest of your crop. Even with the best precautions, reusing glass jars could spread a disease to a new batch of mushrooms.
  • Air circulation and contaminate control Mushroom spawn bags come with a filter patch that keeps out contaminants while allowing proper oxygen exchange to keep the spawn healthy.
  • Spawn colonization It’s important to break up your spawn to spread the mycelium to all parts of the growing medium, which is difficult to do safely inside a glass jar. Mushroom grow bags are pliable, so you can gently massage the substrate without harming the spawn.
  • Transport and safety Moving glass jars full of a growing substrate can be heavy and stressful. Glass jars can break, which can cause cuts and make you lose a precious batch of spawn. Bags won’t shatter, and you can stack large amounts into a sack and easily carry them to a new location.
  • Cost It takes a lot of time and water to clean and reuse glass jars for growing mushroom spawn. Mushroom spawn bags are inexpensive, and you can repurpose the bags after use if you want to conserve plastic waste.
  • Easier spawn transfer When it’s time to transfer your spawn to a larger container full of growing substrate to fruit your mushrooms, bags make this task a breeze.Trying to get colonized spawn out of a jar is challenging, and digging it out with a utensil can damage the mycelium and contaminate the contents. Spawn bags are easy to open to release the contents into a new container with little risk of damage or contamination.
  • Vessel for fruiting Mushroom spawn bags can double as the vessel for fruiting your mushrooms by cutting the sides or top of the bag and exposing the substrate to the air, which saves plenty of hassle.

Features of Mushroom Spawn Bags

To fully understand the different types of bags on the market, I go over common feature terminology.


Gusseted bags have inward folds on the sides that open wide when you fill them. Gussets allow the bag to lay flat, yet hold more material when in use and also provide space to add in a filter to prevent possible post-sterilization contamination.


Growing bags have a small filter patch on the front, which allows you to set mushroom spores into the spawning medium and allows contaminant-free airflow.


Each bag filter will state a micron rating, which is the pore size of the material. Most filters range between 0.2 microns to 5 microns in size.

Mushrooms growers find a 0.5-micron filter the maximum size desirable to avoid contamination issues.


Autoclavable means the bag can withstand high temperatures as found inside an autoclave, pressure cooker, or other types of a sterilizer without melting.


Polypropylene material bags can withstand melting at sustained temperatures near 270-degrees Fahrenheit, which is ideal for most home mushroom growing sterilization operations.


The size and thickness of mushroom spawn bags vary. What size you choose should take your sterilization method and growing space restrictions into account.

Bag material thickness typically ranges between 2 to 4 mil. 2 mil bags are the least expensive but can tear easier than a thicker one if you aren’t careful.

Start Improving Your Mushroom Yield

Now that you understand more about mushroom spawn bags, you can see that incorporating them into your mushroom growing operation can be very beneficial.

Now’s the perfect opportunity to save time, space, and energy by utilizing mushroom spawn bags in your growing routine to achieve even more success!

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