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Bulk Boxes of Organic Substrate & Grain

Mix-and-match mushroom kits & recurring shipments

Lovingly handcrafted with organic ingredients, our mushroom kits give your fungus the extravagant banquet it deserves, with no experience or special equipment required. Fill a box with your preferred ratio of grain and substrate bags, and let us, and the mycelium, do the rest.

Organic Rye

Each bag contains 3.5lbs. of perfectly hydrated sterilized organic rye. With unrivaled nutritional density, rye supports the highest yields, making it the top choice of profession mushroom cultivators. Our grain comes in injection-port spawn bags, ready to inoculate with the mushroom culture of your choice.

Pooptastic Substrate

Our organic, manure-based mushroom substrate is scientifically formulated and tested to support the most vigorous possible mycelial growth. We carefully hand-forage our manure from exceptionally clean, untreated pastures, gifted by happy donkeys and/or horses with organic diets. We compost, age, shred, mix and pasteurize it with care. Each 3.5lb. bag of substrate comes in a high-airflow grow bag designed for mixing spawn and fruiting mushrooms right in the bag.

Note: This kit is specifically formulated for dung-loving mushrooms and may not be optimal for wood-loving mushroom varieties. We do not work with dung-loving mushroom varieties at Fungaia, so we have partnered with our friends at True Blue Genetics. to get you a discount on the best liquid culture on the market: use code FUNGAIA for 20% off.

Subscribe and Save

Both the sterilized grain and substrate bags come in airtight packaging, are shelf stable and can be stored for months in a cool, dry place. To economize our fulfillment and bring you the best possible price, we've created a monthly/quarterly subscription service. To sign up, simply select a bulk box above and click the "Sign Up" button. You'll be prompted to enter your mailing address, then go to our payment processor to set up recurring payments. After that, you can alter your plan, pause shipments or cancel at any time.

Monthly subscriptions are billed and shipped on the 7th of each month, and quarterly shipments go out on the 7th of March, June, September and December (2 weeks before solstices and equinoxes.)

Organic Matters

At Fertile Substrate, we are meticulous about our ingredients, from our spring water to the pastures where we wrangle the choicest poops. We believe that every detail has significance, and we are dedicated to our craft. It won't be hard to see the difference, and we promise that your fungus will thank you, too.

Our Guarantee

We guarantee that your kit will arrive intact and free of contaminants or we will promptly replace it. Once it has been inoculated, this gurantee only applies if you use a liquid culture from True Blue Genetics.