Brown Rice Flour Mushroom Cake Substrate Jars

Priced per jar.

Bulk Pricing:

01-03 = $6.00ea

4-11 = 5.50ea

12-35 = 5.00ea

36+ = 4.50ea

Made to order, usually within 1-3 days.

Once ready, your order will ship the next day.


32 in stock

Product Description


Priced per jar. Bulk Pricing available and automatically applied in cart: 4-11 = 5.50ea | 12-35 = 5.00ea | 36+ = 4.50ea


Made to order, usually within 1-3 days.  Once ready, your order will ship the next day. While our PF Tek jars arrive sterilized and free of contaminants, they are still somewhat perishable. MUST inoculate jars within 2 days of receiving your order for best results. 

Commonly referred to as PF Tek jars, this product is based on methodology that revolutionized amateur mushroom cultivation. We continue to utilize half pint wide mouth Kerr Brand canning jars, filled with the traditional mixture of organic brown rice flour, vermiculite, and water. Since the COVID-19 pandemic and resulting supply chain shortages, this particular jar has become incredibly hard to source, and prices have more than doubled. This vessel remains the preferred container for this method. Our substrate jars are fresh and sterile and come with four cleanly drilled and taped holes in the lids for easy, fuss-free inoculation.

Unlike many other suppliers, our jars are mixed using Kerr wide mouth half pint canning jars. The resulting shorter, squatter cake is thought to be more productive for mushroom formation during the fruiting stage. Following the basic recipe, clean bottled water is mixed with organic brown rice flour and grade 2 medium grain vermiculite. A dry vermiculite layer tops off the mixture. Although the original recipe didn’t call for it, our jars are then sterilized using our steam and pressure sterilizers for best results.

This basic PF Tek recipe will support the mycelium growth of a wide variety of mushroom species. It makes a great basic fruiting cake for oyster mushrooms. Try a variety of cultures in this substrate, or use the colonized cakes as spawn in wood chip beds for establishing outdoor mushroom garden patches!

History of the PF Tek: In the early 90’s Robert McPherson, aka Professor Fanaticus, introduced the world to The classic PF Tek recipe for substrate preparation. The process revolutionized amateur mushroom cultivation, allowing easily accessed ingredients to be mixed and sterilized using commonly available equipment. Simple rice flour is mixed with vermiculite and water and loaded into half pint wide mouth jars. The jar mixture was able to be sterilized reasonably well using a large stock pot with boiling water.

Note to local customers: to ensure freshness, most of our sterilized substrates and media are prepared to order. As a result we do not stock these items on our shelves, or place them into cold storage. Rarely, we may have a handful left over from the day’s run, but please call ahead of time to ensure we can prepare them for pickup.

Note to International customers: due to increased exposure and potential of longer transit times, we do not recommend this product to customers outside the USA. You may still place an order for and receive this product, but you may experience contamination or failure.


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