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Organic Blue Oyster Mushroom Grain Spawn












Skill level | Beginner |
Grow location | Indoor & outdoor |
Spawn shelf life | 4 months (refrigerated) |
Certifications | USDA certified organic |
Bag weight | 6 lbs |
Fruiting temps | 55-75°F |
Our USDA-certified organic blue oyster (Pleurotus ostreatus) grain spawn features a strain that is a fast substrate colonizer. It produces mushrooms with a strong bluish-gray hue, rich umami flavor, and soft meaty texture. Blue oysters are great for beginners, and as our most productive oyster strain, they are reliable indoor year-round producers. If kept in the right conditions, they will yield substantial first, second, and even third harvests (making them one of the best commercial varieties!)
Blue oyster grain spawn can be for indoor cultivation year round. When used for outdoor cultivation, blue oysters are generally cold tolerant and fruit prolifically in early spring or late fall.
Recommended use:
- Blue oyster grain spawn can be used for indoor production using sawdust or straw or outdoors using straw or wood chips. It is also ideal for growing in buckets.
- Do not use grain spawn for log inoculation.
- This is not a mushroom grow kit. Blue oyster grain spawn must be combined with a substrate in order to fruit.
Upon receiving your spawn:
Remove it from the shipping box as soon as possible. Then, unfold the top of the bag, making room for air space. It's also important to check and confirm that the filter patch is not obstructed. This will help the organism breathe and continue to thrive!
Scroll down for specifications, growing, and storage guides.
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- Weight: Approximately 6 lbs
- Hydration: Average of 47%
- Bags: Gusseted 2.2 mil polypropylene
- Filter: High efficiency .2 micron
- Inoculation Rates: 6 lb. bag of grain will inoculate between 120-165 lb. sterilized sawdust, and 100-130 lb. pasteurized straw
- Sterilization method: Commercial grade autoclave sterilized
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Temperature 55-75°F | 13-24°C Humidity (Phase 1: Primordia) 95-100% Humidity (Phase 2: Fruitbody) 85-95% CO2 Sensitivity (Phase 1: Primordia) <1,000 ppm CO2 Sensitivity (Phase 2: Fruitbody) <1,000 ppm - Primordia - The earliest recognizable stage of fruitbody development. Also known as “baby mushrooms” or “mushroom pins.”
- Fruitbody - A fully grown mushroom, the reproductive structure of the organism in which the spores are produced.
- CO2 sensitivity - When CO2 levels are too high, yields will decrease, stems will become long and stringy, caps will be small, and/or growth will halt.
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Oyster mushroom grain spawn can be mixed into sterilized or lime pasteurized substrates including but not limited to hardwood sawdust, straw, and coffee grounds.
Note: Grain spawn must be mixed with bulk substrate before you can fruit it. If you are new to growing mushrooms, we recommend purchasing a book on mushroom cultivation.
Recommended reading:
'Growing Gourmet and Medicinal Mushrooms' by Paul Stamets
'Organic Mushroom Farming and Mycoremediation' by Tradd Cotter
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Oyster spawn can be spread in chopped straw or wood chips as shown in the video below! Making outdoor beds is one of the easiest methods for growing any type of oyster mushroom.
For our complete mushroom beds pamphlet, click here.
Be sure to use clean, untreated products when making outdoor beds.
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If you don't plan to use immediately, you can refrigerate your spawn for up to 4 months.
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Blue oyster mushrooms can easily replace button mushrooms in most recipes and pair well with many cuisines and flavors. Like all oyster mushrooms, they retain water and may develop a viscous texture when under-cooked. If you prefer a firm or dryer texture, continue to cook Oysters until their liquid has reduced and cooked off and they begin to brown.
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Our grain spawn is USDA certified organic and made using organic cultures from our own culture bank. It contains a blend of locally sourced, organic, and non-GMO ingredients from farms in New England and North America.
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If you’re going to consume home-grown mushrooms, make sure to cook your fresh mushrooms thoroughly with heat. If it is your first time eating this species, it is best to start with a small amount to check for allergies, even if cooked.
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Blue Oyster Heaven
This was my first order of Blue Oyster spores. I'm growing in the 5 gallon bucket method. After 20 days in the bucket, the spores have been coming out the holes. I believe that there are at least 15 colonies. The spore are heaven and I can't wait to harvest in a few more days.

High quality
I have shopped around and these are the highest quality you will find!

Favorite Blue Oyster Spawn
I've bought spawn from a few different sources and this is by far my favorite! Great price too.


Great product
I bought one of these bags of inoculated grain spawn and split it between a lb. bag of hardwood substrate and a large bucket of straw substrate. They both took off quickly and without contamination. When the bag arrived it looked as if it needed more time to completely colonize so I waited a week before use. Overall this is a great product for those of us who don't yet have a complete cleanroom set-up for inoculation.

WORTH EVERY PENNY, I wish I could give more than five stars.
I love that I can get fully colonized grain spawn! Six pounds for $30 is a STEAL. I have done it myself before, but you guys just make it too easy! Thank you for everything you do!

This is awesome!
This was a great product. I am a beginner to all of this and this spawn took off like a rocket for me.


Great customer service
I had a bag of blue oyster grain spawn come that wasn't fully colonized. After waiting on it for a bit, it became contaminated. So I contacted North Spore with some pics of what happened and they immediately sent me out another one. The new bag came fully colonized and I had an amazing first flush of blue oysters. These folks are super helpful and the customer service is great.

Excellent spawn
Excellent product, good price point for the weight and quality of others. Made in Maine. Excellent customer service. Look no further, north spores got what you need. I’m anxiously waiting to fruit these oysters! Thanks!

A wonderful product
This spawn worked perfectly for me!! I'm growing in a 5 gallon bucket, and after about three weeks am starting to see fruiting body pining out of my holes!! Can't wait to give them a try next week or so. Easiest thing I've ever grown!!


AMAZINE! So fun and easy
This has been one of the easiest, funnest things I've ever grown. I used the grain spawn and layered it in a food safe bucket (with 1/4" holes drilled all around) with fresh maple chips and straw that I sort of tried to pasteurize with boiling water. I easily could've spread the spawn across 2-3 buckets but I only had 1 bucket. I did this in December 2021 and left it in a plastic bag to maintain moisture while the mycelium grew. It's now February 10th 2022 and almost every single hole is pinning or has a flush!!! I go out and spray it once a day to make sure it's humid. This is my first time ever trying to grow mushrooms and I'm overjoyed with how awesome it has been.