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Main: Brown Rice Flour Technique (PF Tek)

Brown Rice Flour Technique

Also Known as PF Tek


This section of our video is presented in full to help you get started growing mushrooms. The BRF tek video from our DVD is broken here into four parts to make it more compatible for streaming. Simply click on the header or thumbnail image for each section to watch the video.

BRF Tek Part 1


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BRF/PF Tek Part 1

Part 1 of the BRF tek (common slang for technique) gets you started on the easiest way to learn how to grow mushrooms. This technique was originally developed for the cultivation of Psilocybe cubensis, a hallucinogenic mushroom, but is an excellent way to get started growing edible mushrooms as well, without the purchase of such items as a laminar flowhood and pressure cooker.


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Part 1 also gives the recipe and demonstrates the procedure for grinding the brown rice using a coffee grinder. You’ll see how to modify the lids of your mason jars to allow for inoculation and air exchange, and you’ll see how we sterilize the brown rice flour above a kettle of boiling water.

BRF/PF Tek Part 2

Part 2 of the brown rice flour technique (pf tek) picks up where part 1 left off. You’ll remove the sterilized jars from the steaming kettle, and once they’ve cooled to room temperature, inoculate them with either a mushroom spore syringe or liquid culture syringe using sterile procedures as demonstrated by well-known mycologist Jim Read of Seattle, Washington.

This chapter demonstrates the use of a simple ‘glovebox’ made from an inexpensive plastic storage tote you can purchase locally for around $10 or less. The only purpose of the glovebox is to provide an enclosed work area free from the normal drafts in your home. It does not need to be sterile. The only purpose of the glovebox is to provide a place where there is no circulation or ‘wind’ that would otherwise carry possible contaminant mold spores or bacteria from your own breath or body into your sterile media.

You’ll observe as Mr. Read flame sterilizes the needle of his culture syringe before using it to inoculate the sterilized jars of brown rice flour and vermiculite. Once inoculated, the jars are set on a shelf at normal room temperature for 2 to 3 weeks until fully colonized. While normal room temperature is great for colonization, try to keep the ambient temperature below 81F to help prevent the stimulation of thermophilic molds and bacteria.

BRF/PF Tek Part 3

Part 3 of the pf tek videos demonstrates how to build a small fruiting chamber for growing mushrooms, also known as a terrarium, using an inexpensive plastic tote that you’ll purchase locally. The purpose of the terrarium is to provide a semi-enclosed area of high humidity for fruiting your mushrooms. It’s extremely important to also have a means of fresh air entry to your terrarium t stimulate pinning of your mushroom crop, and to prevent stale air. Stale, still air tends to stimulate competitor molds such as the dreaded green meanie Trichoderma, also known as the forest green mold.

You’ll observe in the video clip that we drill numerous small holes into all six sides of the terrarium. A ¼” (6mm) drill bit was used, and up to a few hundred holes will be drilled into larger terrariums. When completed, you'll want to elevate the terrarium an inch or two above your shelf so that air can easily circulate under the unit. Empty ½ pint mason jars, blocks of wood or plastic, etc., can be used to place under your terrarium. If it’s a large terrarium, place a block or two under the center of it as well as under each of the four corners.

Once filled with well-drained perlite, this design will easily maintain upper 90% humidity levels while allowing for the air exchange that is necessary both as a pinning trigger, and also to keep air flowing, which reduces the incidence of contaminant molds.

For this terrarium to function properly, you’ll want to have an ambient humidity in your room of 50% or greater. If you live in a desert or very dry climate, you’ll want to run a cool mist humidifier in the room your terrarium is located to raise the humidity to 50%. This becomes especially critical during the winter months when indoor humidity is often very low.

BRF/PF Tek Part 4


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Chapter 4 picks up as you’ve just placed your cakes in the terrarium. You’ll remember from part 3 that after the dunk and roll, we placed the cakes in our terrarium and misted heavily a few times to moisten the dry vermiculite we previously rolled the cakes in.

The vermiculite covering the cakes serves as both a moisture reservoir and a casing layer. You’ll learn more on casing layers in the chapter titled ‘Casing Layer Preparation’. The purpose of a casing is two-fold. First, the casing supplies moisture to the substrate, which is then delivered by the mycelium to the fruits as they grow. Second, the casing layer provides a miniature climate just above the substrate of very high humidity, which helps stimulate primordia formation.


Part 4 finishes up the BRF tek by showing pictures of the very jars that were inoculated in Part 1 as they begin to fruit, only 4 weeks after inoculation.

Much, much more is presented in the full release of our nearly 4 hour, 2 DVD set Let's Grow Mushrooms!

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Misting your Mushrooms and Fruiting Chamber

It’s very important to keep your casing or vermiculite layer on the cakes well misted throughout the fruiting process. Don’t spray your cakes directly, but rather aim your misting bottle up in the air, so that the mist falls gently on the cakes and developing fruit bodies. Most of the mist will actually fall on the perlite, replenishing the moisture that has evaporated into your fruiting chamber or terrarium. I recommend three or four misting sessions per day. Gently mist your entire terrarium until the cakes ‘glisten’ with moisture. Obtain an inexpensive mechanical hygrometer from a local cigar shop, and then calibrate it by wrapping a damp towel around it for an hour. Next, unwrap the damp towel and adjust the screw on the back so the dial reads 99%. Try to keep your humidity level above 95% all the way through the fruiting process.

After each misting, use the lid of your terrarium to ‘fan’ the inside of the box to remove any stale air that may have accumulated inside. With certain species, such as P cubensis, fanning is not usually as critical as with less CO2 tolerant species such as Oyster mushrooms, which will grow large, fat stems and small, under-developed caps if the air in your terrarium is not exchanged enough. Remember that with oyster mushrooms, we usually discard the stems and only eat the caps, so you want lots of bright light and fresh air.

Lighting requirements for mushroom cultivation

Contrary to popular belief, most mushrooms require light to develop properly. Mushrooms are not plants, thus do not use light as a source of energy in the same way plants do. However, due to many factors, some of which are not yet fully understood, light is extremely important in the primordia forming stage with most fungi, and with species such as P cubensis and the oyster mushrooms (P ostreatus), it’s important to provide bright, high frequency light all the way through to harvest or your fruits will be under-developed and of poor quality. If your oyster mushrooms look like twisted coral formations, or your Shiitake or P cubensis have fat stems and tiny caps, it’s a sure sign that your lighting is not sufficient.

Experience has taught us that bright fluorescent lighting with a color temperature of 5000 Kelvin or above is best for both primordia formation and the development of fruiting bodies across a wide range of mushroom species. Cool-white fluorescent tubes generally deliver a color temperature of 5,000 Kelvin, while natural daylight fluorescent tubes deliver an even better color temperature of 6,000 to 7,000 Kelvin and these are the recommended type. Avoid kitchen and bath fluorescent tubes as these generally deliver a ‘warmer’ light of around 3,000 Kelvin, which is the same color temperature as incandescent light bulbs, also to be avoided. Incandescent bulbs have the added disadvantage of producing most of their energy output as heat rather than light, while the recommended fluorescent tubes produce most of their energy output as light, rather than heat.

12 hours on, 12 hours off has proved over many years of experience to be the best combination when using artificial lighting. If you have a bright window in your growing area, natural sunlight can be used, but direct sunlight should be avoided for more than a few minutes per day. Use blinds or some other method to diffuse the sunlight if natural lighting is used.

Enjoy the Video!

Marc R Keith

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Page last modified on September 21, 2022, at 07:17 AM