Oyster Mushroom DIY Grow Blocks

How to Make Your Own Oyster Mushroom Blocks

DIY Oyster Mushroom Grow Kit

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. Follow the steps below to make your own ready-to-fruit Oyster mushroom blocks:

Keep in mind that Pink oyster mycelium is light and wispy, leading to an "uncolonized" appearance in the spawn. This is normal! Each oyster mushroom mycelium will look different.

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: 2 1⁄2 cups fuel pellets, 1 1⁄2 cup cottonseed hull pellets, 1 cup soy hull pellets, 1 1⁄2 cup grain spawn, and one filter patch bag.

2) Prepare the dry materials
Measure out 2 1⁄2 cups of hardwood fuel pellets, 1 1⁄2 cup cottonseed hull pellets, and 1 cup soy hull pellets (Figure 1). Later you will add 5 1⁄2 of boiling water in order to hydrate the pellets. Add the pellets to a standard 0.2 micron filter patch bag (Figure 2).

3)Hydrate the fuel pellets
Boil 5 1⁄2 cups of water and add to the fuel pellet mixture. Be careful while working with boiling water. Seal or tightly fold over the bag after adding the water (Figure 3). 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 4).

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 (8-12 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 substrate 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 5). 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 62-65°F where they will not be disturbed for 2-3 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 (Figure 6). Blocks will need to incubate for around 20 days before you fruit the blocks, exact time will vary based on temperature. After the incubation period, roll up the excess bag, flip it upside-down, and cut small Xs through the filter patch bag (one on each side). Place the block in an area that you can maintain humidity. Fruiting bodies should start to appear 7-14 days after opening.

Time to fruiting:
7-14 days after setup.
Ideal Fruiting Conditions:
55-70°F, 70-85% humidity
Materials Needed:
Filter patch bags, hardwood fuel pellets, cottonseed hull pellets, soy hull pellets, boiling water, measuring cup, Oyster mushroom grain spawn.
*this kit comes with enough materials to make 8 blocks
How To Video:
Find the kit:

Measure out fuel pellets, cottonseed hull pellets, and soy pellets.

a small pile of fuel pellets and bran on a metal table

Add pellets to the filter patch bag.

bran and fuel pellets inside a filter patch bag

Add boiling water to bag, mix thoroughly, and fold over the top of the bag immedidatley to trap in steam and heat.

rehydrated pellets

Optional: Pack the hot bags into an insulated container for 2 hours to allow for pasteurization. Pasteurization will lead to longer lasting blocks.

hydrated blocks packed into a red cooler

Inoculate each of the blocks immediately after cooling. Shake to mix, then seal the bags with a heat sealer, rubber band, or other means.

bags immediately after being inoculated

Blocks should begin to colonize quickly. These blocks are 7 days old. Overall incubation time varies.

an oyster mushroom block showing healthy mycelium