The many steps and equipment needed to make your own mushroom blocks can be daunting. This easy, low-tech method balances time and cost by eliminating variability with use of fuel pellets and by-passing sterilization.
Keep in mind that Shiitake mycelium is light and wispy, leading to an "uncolonized" appearance in the spawn. This is normal!
How to Make your Own Blocks
1) Gather the Materials
Multiple blocks can be prepared at one time, but for the purpose of this instruction sheet we will instruct per one block. Gather all the materials needed in a clean area, wipe down the countertops. For each block you will need: 5 cups fuel pellets, 1⁄2 cup bran, 1 1⁄2 cup grain spawn, and one filter patch bag.
2) Prepare the dry materials
Measure out 5 cups of hardwood fuel pellets (Figure 1). Later you will add the same volume of boiling water in order to hydrate the pellets. Add the pellets to a standard 0.2 micron filter patch bag (Figure 2). Add 1⁄2 c bran to the fuel pellets and shake the bag to evenly distribute the bran.
3)Hydrate the fuel pellets
Boil 5 cups of water and add to the fuel pellet mixture (Figure 3). Be careful while working with boiling water. Seal or tightly fold over the bag after adding the water (Figure 4). The pellets will quickly heat and expand. Everything in the bag will semi-pasteurize from the steam.
Optional: An additional step of pasteurizing can lead to slightly higher yields. To do this the bags can be packed tightly into storage tubs (or preferably insulated containers that will hold the heat such as a beverage cooler) and allowed to sit for 2 hours in the closed container (Figure 5).
4) Cool the blocks
Place the newly hydrated blocks in the cleanest area possible, with little traffic and air flow. Be sure the bags are folded over tightly to reduce the risk of contamination by common molds. The blocks will need to completely cool before inoculation (12-24 hours).
5) Inoculate the blocks
Inoculate the blocks immediately upon cooling in a clean environment. Spray down work surface with bleach or alcohol and use gloves or thoroughly wash your hands prior to inoculation. The risk of contamination problems increases over time, so the sooner the bags can be inoculated the better. Carefully open the fuel pellet bag, pour in 1 1⁄2 c. grain spawn, fold the top of the bag over, shake to mix, then seal the bag. A rubber band tightly looped works well to seal (Figure 6). Be sure that the filter patch is not blocked to allow for air exchange.
5) Incubate the blocks
Once inoculated, place the blocks in an area with a temperature of 68-72°F where they will not be disturbed for 12 weeks. Incubation time will vary based on temperature and inoculation rate. You should be able to see light strands of mycelium after the first week. After 2-3 weeks you will notice the shiitake block start to "rope" (Figure 7). Several weeks after the roping begins the block will start to brown (Figure 8) - this is good! Shiitake blocks need to "bark" or "brown" over before they are ready to produce mushrooms. You may also notice a brown liquid build up in the bottom of the bag - this is normal. We recommend waiting at least 12 weeks before opening your block, regardless of how long they've been brown. Opening blocks early will result in small, thinner capped mushrooms. To open the blocks, remove the browned block completely from the filter patch bag and place on a shelf or tray in a location where you can maintain 85% humidity and temperatures between 60-70°F. The shiitake should start growing 7-14 days after removing the block from the bag.
