Using Mushroom Grow Bags: Complete Overview & Guide

Introduction to Using Mushroom Grow Bags

Growing mushrooms in a bag is one of the simplest methods to produce your own mushrooms at home. If you’ve ever used a mushroom-growing kit from online stores or specialty shops, you’re already somewhat familiar with this process. Both commercial mushroom farmers and hobbyists use bags for growing mushrooms, now these are not your average freezer baggies, they are specially-designed bags for mushroom cultivation. 

Depending on the substrate or growing medium you choose, bags can be used to grow a wide variety of mushrooms. Mushroom grow bags come in different sizes and thicknesses depending on the mushroom you want to cultivate. With a few basic supplies and careful preparation, you can grow a wide variety of mushrooms in bags, and you’ll be able to produce them more economically and efficiently. Let’s take a better look at how people are growing mushrooms in a bag.

1. Different Types of Mushroom Growing Bags

There are many types of mushroom-growing bags, but usually, they all share similar features. They are all autoclavable, meaning that they can safely be used in an autoclave which is used to sterilize the grain spawn. This means that these bags are resistant to high temperatures which distinguishes them from regular plastic bags which would melt. However, that’s not the only difference. Here are some of the most notable features of a mushroom growing bag:

• Polypropylene: Grow bags are crafted from durable polypropylene plastic, known for its resistance to high temperatures. This material is flexible, long-lasting, and transparent, making it easy to monitor growth progress. Additionally, it’s a cost-effective option.
• Gusseted: Gusseted bags feature folds on the sides, allowing spacious bags to fold flat when not in use. While mushrooms themselves aren’t concerned about whether bags are gusseted or not, this feature aids growers in maintaining organization and storage.
• Filter Patch: A filter patch is a small section of the bag designed to allow air to pass through a fine mesh. This mesh is effective in preventing airborne contaminants and spores of unwanted fungus species from entering the bag.

1. What to Consider When Choosing a Mushroom Growing Bag

• Bag Size: The ideal size depends on the grower’s specific needs and preferences. There are no strict guidelines when choosing a bag size, but make sure it is not too big so it fits in your growing room, and also make sure it’s not too small so that you don’t end up with wasteful yields. 
• Thickness: Mushroom growing bags typically range from 2.2mm to 4.0mm. While thicker bags are stronger and more durable they are also a bit more expensive. Growers who are just starting out can experiment with thinner, more affordable bags and switch to thicker ones in the future.
• Filter Size: Filter sizes range from 0.2mm to 5mm in diameter. Smaller pores allow fewer spores and impurities to pass through but also reduce airflow. The goal is to balance adequate air supply with protection from contaminants. The smaller the filter diameter the better, usually anything from 0.2 to 0.5mm will work perfectly.

2. When to Start Growing Mushrooms in a Bag

Obviously, you can’t grow mushrooms with only an empty bag. A mushroom growing bag is filled with the proper substrate depending on which type of mushroom you are cultivating. For example, oyster mushrooms grow best in cereal straw as a medium, on the other hand, Lion’s mane thrive in hardwood sawdust and wheat barn. The mushroom will consume the nutrients from the growing medium and then grow out of the bag providing an abundant harvest. 

Buying tip: Find top-rated mushroom grow bags on Amazon here. These are the best we’ve found.

Clear plastic mushroom grow bags are primarily used in commercial or large-scale mushroom cultivation. Home growers rarely use these bags, opting instead for the more user-friendly PF Tek Method (link to our guide), which simplifies the process of growing mushrooms at home.

You can place mushroom grow bags on shelves in a warehouse or shed. Since the bags are clear plastic, you can easily see how well the mushrooms are doing and how much they’ve grown.

Additionally, it’s easier to work with growing mushrooms in these bags when it comes time to perform work on the mushrooms. It’s easy to cut bags open, harvest from them, and discard or recycle the material. The most helpful part about using mushroom grow bags is that they make it easy to identify contamination. And, since plastic protects contaminated material from spreading to another bag, this keeps one contaminated bag separate from the other uncontaminated bags. This is extremely important and helpful to a commercial or large-scale mushroom grower.

3. Step-by-Step Guide on Growing Mushrooms In a Bag

Here, we will list the basic steps for using a plastic mushroom grow bag, however, every grower has different methods and styles of working with their materials.

1. 1. Select the Bag and Substrate

First of all, you need to get some grow bags and choose a substrate that you will use to grow mushrooms. Growers use a variety of substrates, as different mushroom species have specific preferences. To achieve the best results, you must match your mushroom species with the appropriate substrate.

While mushroom grow bags can’t usually be found in your neighborhood convenience store, online platforms like Amazon are a great place to get yourself some durable mushroom growing bags. Here’s a link for the Amazon listing.

Once you get the grow bags fill them with the substrate and proceed to the next step. If you don’t know how to choose the substrate or fill the bags, head to our guide here to learn more.

2. 2. Sterilize The Substrate In the Growing Bag

As many mushroom growers know, the sterilization process in growing mushrooms is extremely important. With mushroom growing bags, this means filling your bags with your proper substrate and fully sterilizing them in a high-heat and high-pressure environment. Buying a sturdy high-quality growing bag is essential to prevent ripping or melting under such conditions.

• Fill a large pressure cooker (Amazon link), with enough water to cover the bottom by about an inch. 
• Place your growing bags inside the pressure cooker, leaving enough space for steam circulation.
• Close the lid and set the pressure cooker to its maximum temperature.
• Sterilize the bags for 60 to 90 minutes at 15 PSI.
• Turn off the heat and let the pressure cooker cool down to room temperature before proceeding.
• Once the substrate has completely cooled down inject the spores using a spore syringe. 

3. Incubation

Incubation is the process where mycelium develops over the growing medium. To incubate mushroom grow bags, keep them in a warm sport with a temperature ranging between 64 and 75°F (20-24°C ). After a few days, you will notice small white spots forming in the substrate. These spots will gradually spread and eventually cover the entire bag. The incubation process usually takes about two to four weeks, depending on the mushroom species you are growing.

4. Fruiting

When your grow bags are almost fully colonized with the mushroom mycelium you will have to make a small slit in the top or side to allow the mushrooms to fruit. It’s best to cut a small 2-inch (5 cm) hole on the side of the bag rather than the top, although some growers also cut the top part. Depending on the humidity, mushrooms will start to grow out of your bags in the next 5 to 7 days.

Congratulations, you have successfully cultivated your own mushrooms! As you can see growing mushrooms in a bag isn’t that hard, now you can enjoy your freshly homegrown mushrooms. If you want to learn more about the whole bag spawning process with our guide here.