‘Boomr Bag’ Manure-Based Sterile Mushroom Substrate

$28.99

Maximize your mushroom yield!

Our best-selling Boomr Bag is a sterile manure-based bulk mushroom substrate formulated by mycologists to increase the yield of your grow. Over several years, the recipe has been perfected for dung-loving mushroom species and is widely-trusted by mushroom growers. Use Boomr Bag in monotubs, filter bags, and outdoor beds. Or, grow mushrooms from the bag or in a tray using a humidity-controlled grow room or Martha setup.

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In Stock. Ships in 2-5 business days.

Trusted by 350K+ Growers

Trusted by 350K+ Growers

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Free Shipping over $199

Elevate your indoor mushroom cultivation with North Spore’s ‘Boomr Bag’ Manure-Based Sterile Mushroom Substrate. This premium, ready-to-use sterile substrate provides an ideal foundation for successful and bountiful yields, especially for dung-loving mushroom varieties.

Each ‘Boomr Bag’ contains a precisely formulated blend of pasteurized manure, coco coir, vermiculite, and gypsum, ensuring a rich, nutrient-dense environment. Our meticulous sterilization process guarantees a contaminant-free start, critical for minimizing risks during inoculation and colonization.

Designed for optimal mushroom colonization, this sterile substrate significantly reduces the likelihood of competing molds and bacteria, fostering vigorous mycelial growth. Its robust nutritional profile supports healthy fruiting body development, leading to consistent and high-quality harvests. Key advantages of this premium substrate include:

  • Reduced contamination risk for cultivators
  • Optimal nutrient delivery specifically for dung-loving mushroom varieties
  • Consistent moisture retention for stable growth environments

The convenient 5lb ‘Boomr Bag’ is perfectly suited for use in monotubs, grow tents, and other controlled indoor growing systems. Its consistent moisture content and balanced aeration properties contribute to a stable microclimate essential for mushroom development.

For best results, integrate the ‘Boomr Bag’ into your sterile cultivation practices. Refer to our detailed guides on substrate preparation and inoculation techniques to maximize the potential of your mushroom grow. Explore North Spore's full range of mushroom growing supplies to complete your setup.

Why It's Dope
  • Made entirely from organic materials
  • Balanced pH with a complex nutrient profile
  • Proven vigorous mycelial growth
  • Fast colonization and higher yields
  • Increased aeration and moisture retention 
  • Hydrated to field capacity

Boomr Bag is made from a blend of quality local, organic, and non-GMO materials including a proprietary blend of composted horse manure, coco coir, and several quality substrate supplements (although we keep the exact blend a secret!) Unlike other substrates that contain harmful additives, you can rest assured that your grow will be natural and chemical free.

How to Use

Spawn to bulk ratio

We recommended mixing 1 colonized grain spawn bag with 2-3 bags of sterile substrate. (Higher inoculation rates may improve your success.) 

Best Practices

We recommend clean hands, latex or nitrile gloves, and sterile technique when using sterile substrate to reduce the introduction of contaminants.

Be sure to mix colonized grain spawn thoroughly into your substrate. 

It is best practice to wait a minimum of 1 week after arrival before using sterile substrates to ensure they were not compromised during transit. Rest assured that your purchase is 100% guaranteed. If your substrate was compromised, we will replace it.

Storage

Sterile substrates should be stored at room temperature out of direct sunlight. No refrigeration is necessary. They can also be stored for several months before use.

Made Right, Guaranteed
  • Sterilized in a commercial-grade autoclave for consistent results
  • Multiple bags from every batch tested in our state-of-the-art lab
  • Verified using biological indicators and temperature sensors
  • Backed by our 100% Guarantee — if it’s not sterile, we’ll make it right
Notice

North Spore's products shall be used only for lawful purposes. North Spore does not condone Psilocybin (Psilocybe cubensis) or hallucinogenic (magic) mushroom growing in jurisdictions where it is currently illegal.

CA Prop 65 Notice

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Sterile Substrate FAQs

Choose Boomr Bag for massive flushes of dung-loving species, CVG for versatile bulk grows and great moisture retention (great for beginners), and Wood-Lovr for wood-loving species like oysters, lion’s mane, and reishi. Each is optimized for the best yield and growth rate in its category.

Keep bags at room temperature and out of direct sunlight. Substrates can be stored for several months, and grain bags should be used within a few weeks for best results.

We sterilize our products in commercial autoclaves and test every single batch for bacterial growth so you know the product is sterile when you receive it. And if the bag is compromised in any way during shipping, our 100% guarantee means we'll make it right

While you can grow directly in the bag, the best way to grow with bulk substrate is to to use a monotub.

A general rule is 1 colonized grain bag for every 2–3 substrate bags. Higher spawn ratios often speed up colonization and reduce the risk of contamination.

Grain bags are for colonizing mycelium, while sterile substrates (like Boomr Bag, CVG, or Wood-Lovr) are for fruiting mushrooms. You’ll inoculate the grain bag first, then mix the fully colonized grain with your chosen substrate to begin fruiting.

Cluster of brown-capped mushrooms with long, light-colored stems against a white background.

Lab-Crafted. Grower-Approved.

Get the most out of your grow with our premium sterilized substrates—formulated, hydrated, and sterilized to deliver consistent, high-yield results. Each batch is crafted from organic ingredients and sterilized in a commercial-grade autoclave for contam-free performance. Whether you’re spawning to bulk for the first time or fine-tuning advanced grows, our substrates provide the perfect foundation for strong, healthy mycelial growth.

The right mix for every grow

Our substrates start with premium organic ingredients—nutrient-rich, finely milled, and perfectly balanced for ideal texture, aeration, and moisture. Each blend is designed by mycologists to support vigorous mycelial growth and consistent, high-yield harvests. Built on quality ingredients and precise formulation, they’re the foundation every successful grow begins with.

Reviews

  • 5 stars: 640 (95%)
  • 4 stars: 20 (3%)
  • 3 stars: 5 (1%)
  • 2 stars: 1 (0%)
  • 1 star: 8 (1%)
D
David Pallone
Great Product

Bought an 8-pack of Boomrbags and so far so good. I have 2 monotubs using this bulk substrate that are now almost 100% colonized with no signs of contamination. Substrate bags were easy to use, came perfectly hydrated to field capacity, and didn't require any additional moisture added. I highly recommend using this substrate in a monotub or any other bulk substrate setup.

David Pallone review photo

We're so glad you're loving the Boomr Bags, David! Thanks for the great review.

M
Micha Cargill
Substrate

I love it, they work great!!
I'm going to keep ordering from north spore..
Thank you..

Micha Cargill review photo
S
Shane Mecham
Best substrate around!

I have had many successful grows using BoomrBags and the few times there had been a problem with the bags I get the replacement very quickly. These guys rock!

Shane Mecham review photo
J
John

Best of the best when it comes to customer service and cultivating mushrooms. Thank you for fixing my other order. I will always buy my mushroom supplies from NORTH SPORE.

SINCERELY,
JOHN BONACCI

K
Kyle

Took a lot longer than the listed processing/shipping time. Still have an order I placed before this one that hasnt arrived yet

C
Christopher Brogaard

Just used a 5lb bag of this substrate with 3lbs of innoculated grain spawn we will see in 2 weeks how the tub is looking then.

S
Steven

Great product as Always! Thanks guys

J
John

Great substrate. Monster flushes

C
Chuck Lensing

I finally got it today

S
Steven

Always fast and always great grows!! Thanks guys!

J
Jon
Worth it!

Fast shipping, discreet packaging, I have 3 bags growing like champs, its really very easy!

Thank you! We're so glad to hear everything arrived quickly and your bags are doing well. Happy growing!

E
Ethan

thank you :)

C
Chris
works like its supposed too.

I've innoculated 3 bags with success every time. I'm pretty sure I will continue to use these on all my future grows. I don't see any reason to look elsewhere. Super simple and success is pretty easy with these.

Thanks so much, Chris! We truly appreciate your support.

A
Arturo Fernandez

Awesome product

A
April Wooten

It was exactly what we needed. Excellent products

N
Natasha Melichar
Awesome quality

Super high quality, I add this to my house plants and they thrive!!!!! Fast shipping!

Thanks for the great review, Natasha! We really appreciate your support.

J
Jonuel

Awesome

J
Jason Keene
Great bags

These bags are awesome. Very easy

C
Chelsea
Amazing

This stuff is gold for mushroom growing. Made my first time growing a breeze!

Awesome, Chelsea! Thanks for sharing.

D
Dustin
always an outstanding product

product was well packaged, clean, and as always a number one.

Thanks for sharing, Dustin! We appreciate your support.

J
John

Quick shipping

G
Gabriel

Everything worked great

M
Michael Speaks
Contamination

I purchased an 8 pack of grain and an 8 pack of these boomr bags. All came from the same batch and after using quite a few and getting contamination. I looked closer and saw the boomr bags were contaminated before even opening. I waited a little bit and it grew. I submitted a claim and havent heard anything from north spore. I will say that I have used them plenty times before with no issue but now that I came across one, there doesnt seem to be much support.

T
Tyler

Came Perfectly within days of my order.

J
Jason Keene
Great stuff

These bags are the best bags around. They’re awesome. This is my go to place to buy anything.

This made our day—thank you for the feedback and for choosing us! We hope that you continue to enjoy our products!

D
DCology
Best on the market

Crazy good mixture.

Thanks so much for the review! We couldn't do it without customers like you!

T
Travis Calovich
Excellent

I’ve been loyal to North Spore ever since I first developed interest in educating myself about the process of growing mushrooms! Fast forward to today, and I still shop with North Spore exclusively due how great my experience has been. Even in the event of something unexpected happening North Spore’s customer service has always done an amazing job of fixing it and fast. The company as a whole is bar none top shelf and so I have never had a need for entertaining shopping anywhere else.

K
Kim Buda

Excellent! Always consistant!

J
Jason Keene
Love it

Everything I buy from here is great. I recommend buying it.

Thanks for the great review, Jason!

J
Jason Keene
Great stuff

This stuff works awesome. Buy it every time.

Thanks Jason!