Mushroom Grain Spawn for Growing Your Own Mushrooms

Please be aware that grain spawn may take 3-4 weeks to ship.

What is grain spawn?

At its simplest, grain spawn is the living culture of a fungus, called mycelium, growing on a grain-based material, or substrate. It can be used as a tool for expanding the amount of fungal material you have, through inoculation. Serving a similar function to seeds, spawn is what growers use to start cultivating mushrooms. Where a gardener or farmer might plant a tomato seed to grow a tomato plant, a mushroom gardener or mushroom farmer will use mushroom spawn to grow edible fungi. More info on the difference between growing from spores and from a culture can be found in our Spawn FAQ

Grain spawn is one of the main materials used in commercial scale indoor mushroom production. It has a high nitrogen content, giving the fungi a nutrient boost in their growth from its starter culture to a solid substrate. Different growers prefer different grains, though the most common are millet, wheat, and rye. Here at North Spore, we make our grain spawn with a blend of organic millet and wheat berries. We find there’s a sweet spot in this combination- wheat berries offer great moisture holding capacity, and millet provides a high number of inoculation points due to it’s small particle size. Since grain is nutrient dense, it is more prone to contamination - other competitor fungi, microbes, and even larger creatures in outdoor spaces are eager to eat this rich food. That means in most cases, sterile technique and sterilized or pasteurized materials are recommended for grain spawn applications.

Grain spawn specs

Type: A proprietary blend of sterilized organic grains including millet and wheat berries

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

Storage: All but Pink Oyster should be kept in a refrigerator

Shelf life: Use within 2-3 months

Sterilization: Commercial grade autoclave sterilized

Why choose North Spore?

North Spore is a producer with integrity. We are committed to providing high quality organic grain spawn to commercial and home-scale growers alike. To achieve this, we follow strict protocols for production and employ several quality control checks. North Spore produces all our spawn in-house, primarily by two of our trained mycologists on staff. We sterilize all our grain products in a commercial autoclave, using bioindicators to verify sterilization in each batch. All of our lab work is conducted following proper aseptic techniques that utilize pharmaceutical grade flow hoods and positively pressured work spaces. North Spore maintains an extensive culture bank of over 200 different fungal strains that are cryogenically stored to maintain long term vigor. From this culture bank we select strains based on ease of growth, speed of colonization, and overall fruit body yield and quality. The grain spawn that we produce is always second generation which gives you the option for further expansion.

How do I use grain spawn?

It depends on your scale, space, and equipment. Grain Spawn is most often used for indoor commercial production, but has some applications for the home-grower or enthusiast. Since the grain is nutrient dense, it’s more likely to contaminate than wood based substrates. Unless your project is outdoors, you’ll want to pre-treat your substrate with pasteurization or sterilization to eliminate potential competitor microbes. These processes range from requiring a fair amount of infrastructure for larger scale projects to simple and low-tech for small scale or Oyster mushroom species projects.

Grain Spawn is not used for log inoculation. See plug spawn or sawdust spawn for more information.

Indoor Commercial Scale Production

For species in the Oyster mushroom genus (Pleurotus), grain spawn can be mixed into sterilized or lime pasteurized substrates including but not limited to hardwood sawdust, straw, coffee grounds, and agricultural wastes.

For most other species substrates need to be cooked and sterilized in a steam tank or autoclave. North Spore uses our grain spawn for all in-house production.

We recommend purchasing a book on mushroom cultivation if you are interested in indoor cultivation as a hobby or profession. Some great resources to start with are: 'Radical Mycology: A Treatise on Seeing and Working with Fungi' by Peter McCoy, 'Organic Mushroom Farming and Mycoremediation' by Tradd Cotter, or 'Growing Gourmet and Medicinal Mushrooms' by Paul Stamets.

Check out our cultivation equipment and culture bank to get started!

Outdoor Production*

For species in the Oyster mushroom family, grain spawn can be mixed into straw beds, bales, and less commonly wood chips to form outdoor mushroom beds. Few other species on grain spawn have been used in outdoor applications. Sawdust spawn is a great option for outdoor grows.

*Only certain species of Grain Spawn have been proven to work successfully in outdoor straw, wood chip, or compost beds. When this method is applicable, it will be listed under 'Inoculation Methods' in the species descriptions.

Can I keep my spawn cool during shipment in warmer weather?

North Spore now offers insulated shipping for online grain spawn orders. Our insulated shippers fit up to 4 bags of spawn each, and we charge a flat rate of $30 for the first shipper and $15 for each additional shipper, plus normal shipping costs. This covers the insulated shipper itself, the ice packs we use to keep the spawn cool, and extra shipping costs that result from the added weight of the ice packs. We recommend using insulated shippers as long as daytime temperatures in your area are above 80 degrees. We guarantee that spawn shipped using our insulated shippers will arrive healthy and viable.

Since spawn can still become jostled in shipping, we recommend letting the bags sit at room temperature for 48 hours after receiving before refrigerating again.