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8-Pack Organic Sterilized Grain Spawn Bags














Certifications | USDA certified organic |
Moisture content | Hydrated to a target of 50% |
Carton size | 8 bags (24 lbs) |
Bag weight | 3 lbs each |
A $176 value!
Our best-selling organic sterilized grain spawn bag was formulated by mycologists to maximize the speed and size of your mushroom grow. (All that's required is a spore syringe or liquid culture!)
Each spawn bag contains our proprietary grain blend featuring hydrated, nutrient-rich, organic millet and wheat berries. Bags also include a self-healing injection port for use with a spore or culture syringe plus a 0.2 micron filter patch to block airborne contaminants while providing even gas exchange. Note: Color of injection port may vary.
Spawn to bulk ratio
We recommended 1 lb of colonized grain spawn for every 5 lbs of manure or hardwood sterile substrate. We also recommend using 2.5-5ccs per 3 lb injection port bag. (See Inoculation and Colonization below for full details.)
Why millet?
Millet has a much lower endospore load than rye and wheat, making it less prone to contamination. And its small size means your spawn will have many more inoculation points for the same volume of grain. By using millet, the mycelium will spread more evenly and abundantly through the substrate. And, as a high-nutrient medium, it also encourages rapid mycelial expansion.
Sterilization
North Spore grain spawn bags are sterilized in a commercial-grade autoclave. Sterility is verified using biological indicators and temperature sensors.
Looking for single bags? Click here.
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To inoculate the grain bag, simply inject your spore or culture syringe through the port in a sterile location. We always recommend clean hands and latex or nitrile gloves to reduce the introduction of contaminants.
It is best practice to wait a minimum of 1 week after arrival before injecting grain bags to ensure they were not compromised during transit. Rest assured that your purchase is 100% guaranteed. If your bag was compromised, we will replace it.
We recommend using 2.5-5ccs per 3lb injection port bag. We do not typically recommend using an entire syringe in one bag. Doing so adds excessive moisture which can create over saturation in the bag. This over-saturation can pool and is prone to being anaerobic and the mycelium will have a hard time colonizing.
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Allow your bag to colonize in a cool location out of direct sunlight. Temperature for incubation shouldn't exceed 75 degrees F or dip below 55 degrees F. After a couple weeks, you should start to see mycelium growing on the grain.
You'll notice the white mycelium growing outward from the injection point. When it has grown three to four inches you should, without opening the bag, carefully break up the colonized grain and mix it into the uncolonized grain. This will dramatically speed up the colonization process.
When the bag is completely white with mycelium your spawn is ready to use. This may take a couple weeks to a month or more depending on the species and vigor of your culture.
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Grain bags should be stored at room temperature out of direct sunlight. No refrigeration is necessary. They can also be stored for several months before use.
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North Spore's products shall only be used for lawful purposes. North Spore does not condone hallucinogenic mushroom growing in jurisdictions where it is illegal.
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- Reviews
- Questions
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I have bought these as singles and a couple at a time. So happy I jumped to the bigger number. I have never had a bag of their sterilized grain be contaminated. Now that's a percentage we are looking for.
North Spore
Thanks for sharing, Kelly! Our team is here if you need anything!

Highly recommend!
I've used 4 of these so far and ever single one worked! If your new to growing your own mushrooms this is the best way to learn.
North Spore
Thanks so much, Dustin! Our team is here if you need anything!

Always fantastic quality
Your grain spawn bags have never contaminated and always colonize fast. Love the quality consistently from you guys.
North Spore
We're so happy you're loving these bags, Garrett! If you need help with anything, please reach out.

They'll give you just what you needed
While listening to one of my favorite mushroom podcasts, the host recommended North Spore. I decided to give them a shot and I ordered some substrate, I wanted a trustworthy brand, and they sure did deliver. If you're looking for quality at a great price this is it. I always get a plentiful yield and the fruit taste amazing.
North Spore
Your review made our day, Christine! We couldn’t do it without customers like you.

Great customer service
Had a couple bags that came contaminated and they agreed to replace them but needed the little white stickers with the batch numbe4s so don't loose those stickers or take off just incase.
North Spore
Thanks for sharing, Kristine! If you need help with anything, please reach out.

best bang for buck
great quality, 100 % inoculation rate thus far.
North Spore
Thanks for the great review, Siobhan! We really appreciate your support.

Definitely recommend!
Lots of great product, quick spawn, and easy.
North Spore
Thanks, Austin! The team is here to help if you ever need anything.

Tried and True
All of North Spores products are phenomenal. Frequent customer.
North Spore
Thanks for the great review, Aaron! We really appreciate your support.

Awesome
Fast and easy and sure will buy again soon.
North Spore
Thanks for the great review, Eduardo! We really appreciate your support.

Grain bags
Good except My winecap Seems to have stalled. Other innoculations are on point.
North Spore
Thanks for sharing, Lisa! If you need help with anything, please reach out.