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Mushroom Grow Bags: The Convenient Way to Cultivate Mushrooms

How often do you grow something other than mold in a bag? It may be an unfamiliar growing method, but it’s easy and effective if you’re growing mushrooms.

To cultivate healthy mushrooms, instead of buying them, you’ll need a mushroom grow bag. With it, you can monitor the mushrooms’ progress and ensure a clean, sterile crop.

Read on to learn about mushroom grow bags and how to cultivate them with them!

Mushroom grow bags

Our Top Picks

Best Overall:
Fitwick Extra-Thick Mushroom Grow Bags

Fast Sterilization:
Sucohan’s Sealable Mushroom Grow Bags

Best Budget:
Unicorn 14A Mushroom Grow Bags

Easy Inoculation:
Milliken Mushroom Grow Bags


What are Mushroom Grow Bags?

Their title says it all: They’re bags in which you can grow mushrooms. However, they’re not generic bags that you can select at random.

Mushroom grow bags are made of polypropylene. It’s a durable thermoplastic that withstands high pressure and temperature of up to about 250 degrees Fahrenheit.

Autoclavable is another word to describe this heat-resistant material. For healthy mushroom growth, you’d need to put the bags in an autoclave or a pressure cooker to sterilize the substrate.

The small patch of mesh on the front of the grow bag is a filter patch. It filters out mold and bacteria and lets clean air pass through while the bag remains sealed.


Reasons for Growing Mushrooms in Bags

Maitake mushrooms and shiitake mushrooms on a bamboo colander.

Budgetary Option

As you would with fruits and vegetables, you can grow mushrooms without having to buy them in a store. It’s also worth mentioning that the bags are cheap, which is an incentive to try growing mushrooms!

Easy to Mix the Spawn

When mixing things in a bowl or bucket, the process can be either too tough or messy. With mushroom grow bags, you can easily squeeze and move the substrate and spawn around in the bag for effective colonization.

Improved Monitoring

Checking your mushrooms’ progress as they’re growing is important. With a clear and plastic mushroom grow bag, you’ll have no problems monitoring the mushrooms from any angle. You’ll be able to make easy, necessary adjustments to the substrate.


How to Grow Mushrooms in Bags

Different fresh wild mushrooms in bowl on black background, flat lay

Step One: Gather Your Tools

The following items are what you’ll need to cultivate mushrooms:

When working with mushroom grow bags and the contents to it, you want to keep things as sterile as possible.

Step Two: Obtain the Appropriate Substrate

Like soil for plants, substrate is a growing medium for mushrooms. There are several types of substrate for cultivating certain kinds of mushrooms. Examples include sawdust, straw pellets, and wood chips or shavings.

Fill the grow bag loosely with your chosen substrate; the amount depends on the bag size. When filling mushroom grow bags, leave at least 30% of the top empty, and don’t block the filter patch. This allows for more air exchange, benefitting your mushrooms’ health and crop yield.

Step Three: Place the Bag in a Pressure Cooker or Autoclave

Place your filled bag in a sterilizer (a pressure cooker or an autoclave) and pour in about 2 inches of water. Keep the level lower than the height of the bag’s filter patch. Then set the sterilizer at a low temperature and let the bag sit for three hours.

During that time, the substrate heats up to give the fungal root system the proper growing environment. This root system is known as the mycelium.

After shutting off the sterilizer, let the mushroom grow bag cool down for 10–12 hours.

Step Four: Seal and Inoculate

Seal the bag as soon as you open the sterilizer or after you’ve filled the bag. Some mushroom grow bags have impulse sealers, while others require wire or zip ties.

If the bag has no injection port, stick a strip of packing tape on the back of the bag. This is the side that doesn’t have the filter patch.

Then take a sterile needle and syringe and inject the mushroom spawn through the tape into the bag. Seal the injection site with another strip of tape when you’re done and squeeze the bag to mix everything in.

Step Five: Store the Bag in a Cold Dark Room

After the inoculation, store the bag in a dark room that’s 68–75 degrees Fahrenheit so the mycelium can colonize the substrate. This is the incubation period; in a few days or weeks, you’ll see white spots forming on the substrate.

Step Six: Begin the Fruiting Process

The mushrooms are ready to grow if white spots completely cover the mushroom grow bag. With sterile scissors, cut a 2-inch X shape on one side of the bag and pull away the flaps. If you have a really large bag, cut another X on the same side.

Avoid cutting the bag’s top lest the substrate dries out and gives you a small crop of mushrooms. Curl up the empty space so the mushrooms won’t grow upward. They should only grow through the X-shaped openings.

Finally, spray the bag once or twice daily with water to provide humidity for the mushrooms. But don’t over-spray since mushrooms don’t need water like plants do.

Maintain Fruiting Conditions

Place the mushroom grow bag where there’s indirect or fluorescent lighting to prevent mold growth. The bag should also be under warm or cool temperatures depending on the mushroom variety.

Give your mushrooms more airflow by putting the bag near a window or in an open space. This will help them grow plump instead of long and thin. And check that the substrate doesn’t dry out; in case it does, inject clean water and tape the site.

Step Seven: Harvest Your Mushrooms

The mushrooms take a few days to appear and a few weeks or months to mature. There are different ways to tell if your mushrooms are ready to harvest depending on your chosen variety. They include longer spines, slowed or stopped growth, and opened but not fully flat caps.

At harvest time, twist the stems and pull. They should come away easily; if not, wait another day to harvest. Don’t wait too long to do so, or they’ll rot in the bag or release tons of spores.


The Best Mushroom Grow Bags

Are you ready to try your hand at growing mushrooms in bags? Take a look at these four bags that we recommend:


Best Overall

Fitwick Extra-Thick Mushroom Grow Bags

25PACK Mushroom Grow Bags, Large Extra Thick 6 Mil Spawn Bags , 8" X 5" X 20" 0.2 Micron Filter Breathable, Mushroom Growing Bags for Substrate Autoclavable, Mushroom Bag Tear Resistant Strong (25)

Fitwick’s grow bags are so thick (6,000 microinches) that they can resist up to 399 degrees Fahrenheit during sterilization! No matter what sterilizer you use, with the bags wrapped in aluminum foil, they won’t melt or stick.

These sturdy bags provide a healthy mushroom-growing environment and will stand up when filled with substrate. They’re also breathable, and the 7.9-microinch filter staves off contaminants well.


Fast Sterilization

Sucohan’s Sealable Mushroom Grow Bags

SUCOHANS Mushroom Grow Bags XLS Extra Large Size 10'' x 5.5'' x 24'' /Sealable Spawn/Myco Bags with 0.5 Micron Filter Designed for Mushroom Cultivation Growing (20)

If you’d rather not wait for hours for your bags to sterilize, Sucohan’s 3,000-microinch polypropylene grow bags are for you! These autoclavable bags sterilize six to seven times faster than other grow bags and are best for bulk substrate.

These bags are easy to use and easy to seal thanks to their impulse sealers. You can also mount them to a window should you need more airflow for the mushrooms.


Best Budget

Unicorn 14A Mushroom Grow Bags

These affordable Unicorn grow bags are great for standard mushroom cultivation and hold 5 to 6 pounds of hydrated substrate. Besides being made of 2200-inch polypropylene, they’re made of additives that enable them to withstand agitation and any temperature.

They’re also side-gusseted—meaning these sturdy bags will stand up after they’re filled with substrate—and easy to seal after sterilization.


Easy Inoculation

Milliken Mushroom Grow Bags

Forget about jabbing and sealing a hole on the opposite side of their 7.9-microinch filter patches. With these 3,000-microinch Milliken grow bags, you can inoculate the mushroom spawn through self-healing injection ports.

In addition to effectively reducing chances of contamination, you’ll find that these durable bags remain flexible after sterilization.


Mushroom Grow Bag Buyer’s Guide

When buying mushroom grow bags, focus on these three main features to ensure you choose the best ones.

Bag Size

Think about the size of your sterilizing device and the size of your desired crop. You want the bags to fit inside your sterilizer and hold the amount of substrate you need for your mushrooms.

Filter Pore Size

The pore size in each filter patch ranges between 7.9 and 197 microinches. The smaller the size of each pore, the fewer contaminants can pass through. However, a smaller size means less air passes through as well.

You want your mushrooms to receive clean, fresh air, so it’s a matter of balancing that out with effective protection. As long as the pore size is no bigger than 19.7 microinches, you’ve got a good grow bag.

Bag Thickness

You want thick, strong bags, but the thicker they are, the more expensive they can be. The normal thickness range is 2,200–4,000 microinches. Start with an inexpensive bag; if it holds the substrate and resists high heat well, you’ve got your bag. Otherwise, go for a thicker one.


Growing Spawn in Mushroom Grow Bags

The bags aren’t just for growing mushrooms; they can be for growing spawn, too. You can easily break down and mix around spawn in grow bags. This accelerates colonization, and transferring the spawn to other grow bags is easier from a bag unlike from a jar.


Grow Your Mushrooms in a Bag!

Mushroom grow bags are proof that bags can help grow something healthy. As you watch your mushrooms progress, you’ll find this growing method convenient and easy to work. And in the end, you’ll receive sterile, edible mushrooms!

Visit our mushrooms page to learn more about growing mushrooms and the various types you can cultivate!